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SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0256 PM CDT Thu Aug 15 2024 Valid 152000Z - 161200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM CENTRAL OK TO THE MID MS VALLEY... ...SUMMARY... Scattered severe thunderstorms are possible across parts of the Midwest through tonight. Severe gusts capable of wind damage and large hail are the primary risks with the stronger thunderstorms. A cluster of storms is ongoing across eastern Nebraska and will move into an increasingly unstable environment across Iowa later this afternoon and this evening. Have expanded the slight risk farther north into Iowa to account for this threat. See MCD #1907 for more discussion of this threat. Elsewhere, the forecast remains on track. Thunderstorm development appears imminent along a frontal boundary in Oklahoma within the next 1 to 2 hours. A somewhat similar environment exists farther southwest across portions of northwest Texas and the Texas Panhandle. However, slightly warmer temperatures around 500mb may limit updraft intensity somewhat and thus mitigate a greater severe weather threat. A few storms have developed over the higher terrain in central Idaho and southwest Montana. These storms may pose some severe wind threat as they move northeast. However, instability is quite weak (100-250 J/kg MLCAPE) and should keep any threat mostly isolated. A few large hail and severe wind gusts have occurred across New Hampshire this afternoon and a few additional strong to severe storms may develop in the region, in addition to the ongoing cluster now in northern Massachusetts. This threat should persist through early evening before waning near or shortly after sunset. ..Bentley.. 08/15/2024 .PREV DISCUSSION... /ISSUED 1124 AM CDT Thu Aug 15 2024/ ...Mid MS Valley this afternoon/evening... The remnants of overnight convection, and an associated/lead shortwave trough, are moving across southern MO/IL. Though these storms will likely weaken through midday, a diffuse outflow/differential heating zone may help focus additional thunderstorm development this afternoon. Southern MO to southern IL will be along the southern fringe of the stronger midlevel flow, where a mix of multicell clusters and possibly a supercell or two capable of producing damaging winds (60-70 mph) and isolated large hail (1-1.5 inches in diameter) will be possible later this afternoon/evening. The primary midlevel shortwave trough will progress eastward from NE/SD toward the upper MS Valley by tonight, in conjunction with a surface cold front. Weak, ongoing convection across north central and northeast NE reflects the zone of ascent spreading east-southeastward through the afternoon, toward the destabilizing warm sector in the wake of overnight convection across northern MO/southern IA. Though timing is still a bit uncertain, thunderstorm development appears probable late this afternoon or this evening across eastern NE and especially near the MO/IA border. Relatively long/straight hodographs, midlevel lapse rates near 7.5 C/km and MLCAPE in excess of 2000 J/kg will support supercells capable of producing large hail (1-2 inches in diameter) and damaging gusts (60-75 mph). Some upscale growth into a cluster may also occur as the storms spread east-southeastward toward IL tonight. ...OK this afternoon/evening... Strong surface heating is ongoing across central OK along a weak pre-frontal trough. Mid-upper flow will be weak this far southwest, but deep mixing with surface heating will contribute to steep low-level lapse rates and MLCAPE of 1500 J/kg or greater with minimal convective inhibition. Scattered thunderstorms are expected along this trough by mid-late afternoon, when isolated damaging downburst winds (60-75 mph) will be possible. ...New England this afternoon... To the west of a closed low over Nova Scotia, an embedded shortwave trough is rotating southward over New England with ongoing convection in southwest ME and NH. Surface heating/destabilization on the western/southern fringes of the ongoing storms will likely contribute to additional thunderstorm development this afternoon. Moderate buoyancy and steepening low-level lapse rates, as well as cool midlevel temperatures (-14 to -15 C at 500 mb), will support the potential for isolated wind damage with 45-60 mph gusts and isolated hail approaching 1 inch in diameter with multicell clusters. See MD #1557 for additional information. ...Northern Rockies this afternoon/evening... A midlevel trough will eject east-northeastward over ID/southwest MT/extreme northwest WY through this evening. Steep lapse rates and modest PW (near or less than 0.75 inches) will support high-based thunderstorm development this afternoon in the zone of ascent preceding the midlevel trough. Strong outflow gusts (50-60 mph) will be the main concern. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0256 PM CDT Thu Aug 15 2024 Valid 152000Z - 161200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM CENTRAL OK TO THE MID MS VALLEY... ...SUMMARY... Scattered severe thunderstorms are possible across parts of the Midwest through tonight. Severe gusts capable of wind damage and large hail are the primary risks with the stronger thunderstorms. A cluster of storms is ongoing across eastern Nebraska and will move into an increasingly unstable environment across Iowa later this afternoon and this evening. Have expanded the slight risk farther north into Iowa to account for this threat. See MCD #1907 for more discussion of this threat. Elsewhere, the forecast remains on track. Thunderstorm development appears imminent along a frontal boundary in Oklahoma within the next 1 to 2 hours. A somewhat similar environment exists farther southwest across portions of northwest Texas and the Texas Panhandle. However, slightly warmer temperatures around 500mb may limit updraft intensity somewhat and thus mitigate a greater severe weather threat. A few storms have developed over the higher terrain in central Idaho and southwest Montana. These storms may pose some severe wind threat as they move northeast. However, instability is quite weak (100-250 J/kg MLCAPE) and should keep any threat mostly isolated. A few large hail and severe wind gusts have occurred across New Hampshire this afternoon and a few additional strong to severe storms may develop in the region, in addition to the ongoing cluster now in northern Massachusetts. This threat should persist through early evening before waning near or shortly after sunset. ..Bentley.. 08/15/2024 .PREV DISCUSSION... /ISSUED 1124 AM CDT Thu Aug 15 2024/ ...Mid MS Valley this afternoon/evening... The remnants of overnight convection, and an associated/lead shortwave trough, are moving across southern MO/IL. Though these storms will likely weaken through midday, a diffuse outflow/differential heating zone may help focus additional thunderstorm development this afternoon. Southern MO to southern IL will be along the southern fringe of the stronger midlevel flow, where a mix of multicell clusters and possibly a supercell or two capable of producing damaging winds (60-70 mph) and isolated large hail (1-1.5 inches in diameter) will be possible later this afternoon/evening. The primary midlevel shortwave trough will progress eastward from NE/SD toward the upper MS Valley by tonight, in conjunction with a surface cold front. Weak, ongoing convection across north central and northeast NE reflects the zone of ascent spreading east-southeastward through the afternoon, toward the destabilizing warm sector in the wake of overnight convection across northern MO/southern IA. Though timing is still a bit uncertain, thunderstorm development appears probable late this afternoon or this evening across eastern NE and especially near the MO/IA border. Relatively long/straight hodographs, midlevel lapse rates near 7.5 C/km and MLCAPE in excess of 2000 J/kg will support supercells capable of producing large hail (1-2 inches in diameter) and damaging gusts (60-75 mph). Some upscale growth into a cluster may also occur as the storms spread east-southeastward toward IL tonight. ...OK this afternoon/evening... Strong surface heating is ongoing across central OK along a weak pre-frontal trough. Mid-upper flow will be weak this far southwest, but deep mixing with surface heating will contribute to steep low-level lapse rates and MLCAPE of 1500 J/kg or greater with minimal convective inhibition. Scattered thunderstorms are expected along this trough by mid-late afternoon, when isolated damaging downburst winds (60-75 mph) will be possible. ...New England this afternoon... To the west of a closed low over Nova Scotia, an embedded shortwave trough is rotating southward over New England with ongoing convection in southwest ME and NH. Surface heating/destabilization on the western/southern fringes of the ongoing storms will likely contribute to additional thunderstorm development this afternoon. Moderate buoyancy and steepening low-level lapse rates, as well as cool midlevel temperatures (-14 to -15 C at 500 mb), will support the potential for isolated wind damage with 45-60 mph gusts and isolated hail approaching 1 inch in diameter with multicell clusters. See MD #1557 for additional information. ...Northern Rockies this afternoon/evening... A midlevel trough will eject east-northeastward over ID/southwest MT/extreme northwest WY through this evening. Steep lapse rates and modest PW (near or less than 0.75 inches) will support high-based thunderstorm development this afternoon in the zone of ascent preceding the midlevel trough. Strong outflow gusts (50-60 mph) will be the main concern. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0256 PM CDT Thu Aug 15 2024 Valid 152000Z - 161200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM CENTRAL OK TO THE MID MS VALLEY... ...SUMMARY... Scattered severe thunderstorms are possible across parts of the Midwest through tonight. Severe gusts capable of wind damage and large hail are the primary risks with the stronger thunderstorms. A cluster of storms is ongoing across eastern Nebraska and will move into an increasingly unstable environment across Iowa later this afternoon and this evening. Have expanded the slight risk farther north into Iowa to account for this threat. See MCD #1907 for more discussion of this threat. Elsewhere, the forecast remains on track. Thunderstorm development appears imminent along a frontal boundary in Oklahoma within the next 1 to 2 hours. A somewhat similar environment exists farther southwest across portions of northwest Texas and the Texas Panhandle. However, slightly warmer temperatures around 500mb may limit updraft intensity somewhat and thus mitigate a greater severe weather threat. A few storms have developed over the higher terrain in central Idaho and southwest Montana. These storms may pose some severe wind threat as they move northeast. However, instability is quite weak (100-250 J/kg MLCAPE) and should keep any threat mostly isolated. A few large hail and severe wind gusts have occurred across New Hampshire this afternoon and a few additional strong to severe storms may develop in the region, in addition to the ongoing cluster now in northern Massachusetts. This threat should persist through early evening before waning near or shortly after sunset. ..Bentley.. 08/15/2024 .PREV DISCUSSION... /ISSUED 1124 AM CDT Thu Aug 15 2024/ ...Mid MS Valley this afternoon/evening... The remnants of overnight convection, and an associated/lead shortwave trough, are moving across southern MO/IL. Though these storms will likely weaken through midday, a diffuse outflow/differential heating zone may help focus additional thunderstorm development this afternoon. Southern MO to southern IL will be along the southern fringe of the stronger midlevel flow, where a mix of multicell clusters and possibly a supercell or two capable of producing damaging winds (60-70 mph) and isolated large hail (1-1.5 inches in diameter) will be possible later this afternoon/evening. The primary midlevel shortwave trough will progress eastward from NE/SD toward the upper MS Valley by tonight, in conjunction with a surface cold front. Weak, ongoing convection across north central and northeast NE reflects the zone of ascent spreading east-southeastward through the afternoon, toward the destabilizing warm sector in the wake of overnight convection across northern MO/southern IA. Though timing is still a bit uncertain, thunderstorm development appears probable late this afternoon or this evening across eastern NE and especially near the MO/IA border. Relatively long/straight hodographs, midlevel lapse rates near 7.5 C/km and MLCAPE in excess of 2000 J/kg will support supercells capable of producing large hail (1-2 inches in diameter) and damaging gusts (60-75 mph). Some upscale growth into a cluster may also occur as the storms spread east-southeastward toward IL tonight. ...OK this afternoon/evening... Strong surface heating is ongoing across central OK along a weak pre-frontal trough. Mid-upper flow will be weak this far southwest, but deep mixing with surface heating will contribute to steep low-level lapse rates and MLCAPE of 1500 J/kg or greater with minimal convective inhibition. Scattered thunderstorms are expected along this trough by mid-late afternoon, when isolated damaging downburst winds (60-75 mph) will be possible. ...New England this afternoon... To the west of a closed low over Nova Scotia, an embedded shortwave trough is rotating southward over New England with ongoing convection in southwest ME and NH. Surface heating/destabilization on the western/southern fringes of the ongoing storms will likely contribute to additional thunderstorm development this afternoon. Moderate buoyancy and steepening low-level lapse rates, as well as cool midlevel temperatures (-14 to -15 C at 500 mb), will support the potential for isolated wind damage with 45-60 mph gusts and isolated hail approaching 1 inch in diameter with multicell clusters. See MD #1557 for additional information. ...Northern Rockies this afternoon/evening... A midlevel trough will eject east-northeastward over ID/southwest MT/extreme northwest WY through this evening. Steep lapse rates and modest PW (near or less than 0.75 inches) will support high-based thunderstorm development this afternoon in the zone of ascent preceding the midlevel trough. Strong outflow gusts (50-60 mph) will be the main concern. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0256 PM CDT Thu Aug 15 2024 Valid 152000Z - 161200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM CENTRAL OK TO THE MID MS VALLEY... ...SUMMARY... Scattered severe thunderstorms are possible across parts of the Midwest through tonight. Severe gusts capable of wind damage and large hail are the primary risks with the stronger thunderstorms. A cluster of storms is ongoing across eastern Nebraska and will move into an increasingly unstable environment across Iowa later this afternoon and this evening. Have expanded the slight risk farther north into Iowa to account for this threat. See MCD #1907 for more discussion of this threat. Elsewhere, the forecast remains on track. Thunderstorm development appears imminent along a frontal boundary in Oklahoma within the next 1 to 2 hours. A somewhat similar environment exists farther southwest across portions of northwest Texas and the Texas Panhandle. However, slightly warmer temperatures around 500mb may limit updraft intensity somewhat and thus mitigate a greater severe weather threat. A few storms have developed over the higher terrain in central Idaho and southwest Montana. These storms may pose some severe wind threat as they move northeast. However, instability is quite weak (100-250 J/kg MLCAPE) and should keep any threat mostly isolated. A few large hail and severe wind gusts have occurred across New Hampshire this afternoon and a few additional strong to severe storms may develop in the region, in addition to the ongoing cluster now in northern Massachusetts. This threat should persist through early evening before waning near or shortly after sunset. ..Bentley.. 08/15/2024 .PREV DISCUSSION... /ISSUED 1124 AM CDT Thu Aug 15 2024/ ...Mid MS Valley this afternoon/evening... The remnants of overnight convection, and an associated/lead shortwave trough, are moving across southern MO/IL. Though these storms will likely weaken through midday, a diffuse outflow/differential heating zone may help focus additional thunderstorm development this afternoon. Southern MO to southern IL will be along the southern fringe of the stronger midlevel flow, where a mix of multicell clusters and possibly a supercell or two capable of producing damaging winds (60-70 mph) and isolated large hail (1-1.5 inches in diameter) will be possible later this afternoon/evening. The primary midlevel shortwave trough will progress eastward from NE/SD toward the upper MS Valley by tonight, in conjunction with a surface cold front. Weak, ongoing convection across north central and northeast NE reflects the zone of ascent spreading east-southeastward through the afternoon, toward the destabilizing warm sector in the wake of overnight convection across northern MO/southern IA. Though timing is still a bit uncertain, thunderstorm development appears probable late this afternoon or this evening across eastern NE and especially near the MO/IA border. Relatively long/straight hodographs, midlevel lapse rates near 7.5 C/km and MLCAPE in excess of 2000 J/kg will support supercells capable of producing large hail (1-2 inches in diameter) and damaging gusts (60-75 mph). Some upscale growth into a cluster may also occur as the storms spread east-southeastward toward IL tonight. ...OK this afternoon/evening... Strong surface heating is ongoing across central OK along a weak pre-frontal trough. Mid-upper flow will be weak this far southwest, but deep mixing with surface heating will contribute to steep low-level lapse rates and MLCAPE of 1500 J/kg or greater with minimal convective inhibition. Scattered thunderstorms are expected along this trough by mid-late afternoon, when isolated damaging downburst winds (60-75 mph) will be possible. ...New England this afternoon... To the west of a closed low over Nova Scotia, an embedded shortwave trough is rotating southward over New England with ongoing convection in southwest ME and NH. Surface heating/destabilization on the western/southern fringes of the ongoing storms will likely contribute to additional thunderstorm development this afternoon. Moderate buoyancy and steepening low-level lapse rates, as well as cool midlevel temperatures (-14 to -15 C at 500 mb), will support the potential for isolated wind damage with 45-60 mph gusts and isolated hail approaching 1 inch in diameter with multicell clusters. See MD #1557 for additional information. ...Northern Rockies this afternoon/evening... A midlevel trough will eject east-northeastward over ID/southwest MT/extreme northwest WY through this evening. Steep lapse rates and modest PW (near or less than 0.75 inches) will support high-based thunderstorm development this afternoon in the zone of ascent preceding the midlevel trough. Strong outflow gusts (50-60 mph) will be the main concern. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0256 PM CDT Thu Aug 15 2024 Valid 152000Z - 161200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM CENTRAL OK TO THE MID MS VALLEY... ...SUMMARY... Scattered severe thunderstorms are possible across parts of the Midwest through tonight. Severe gusts capable of wind damage and large hail are the primary risks with the stronger thunderstorms. A cluster of storms is ongoing across eastern Nebraska and will move into an increasingly unstable environment across Iowa later this afternoon and this evening. Have expanded the slight risk farther north into Iowa to account for this threat. See MCD #1907 for more discussion of this threat. Elsewhere, the forecast remains on track. Thunderstorm development appears imminent along a frontal boundary in Oklahoma within the next 1 to 2 hours. A somewhat similar environment exists farther southwest across portions of northwest Texas and the Texas Panhandle. However, slightly warmer temperatures around 500mb may limit updraft intensity somewhat and thus mitigate a greater severe weather threat. A few storms have developed over the higher terrain in central Idaho and southwest Montana. These storms may pose some severe wind threat as they move northeast. However, instability is quite weak (100-250 J/kg MLCAPE) and should keep any threat mostly isolated. A few large hail and severe wind gusts have occurred across New Hampshire this afternoon and a few additional strong to severe storms may develop in the region, in addition to the ongoing cluster now in northern Massachusetts. This threat should persist through early evening before waning near or shortly after sunset. ..Bentley.. 08/15/2024 .PREV DISCUSSION... /ISSUED 1124 AM CDT Thu Aug 15 2024/ ...Mid MS Valley this afternoon/evening... The remnants of overnight convection, and an associated/lead shortwave trough, are moving across southern MO/IL. Though these storms will likely weaken through midday, a diffuse outflow/differential heating zone may help focus additional thunderstorm development this afternoon. Southern MO to southern IL will be along the southern fringe of the stronger midlevel flow, where a mix of multicell clusters and possibly a supercell or two capable of producing damaging winds (60-70 mph) and isolated large hail (1-1.5 inches in diameter) will be possible later this afternoon/evening. The primary midlevel shortwave trough will progress eastward from NE/SD toward the upper MS Valley by tonight, in conjunction with a surface cold front. Weak, ongoing convection across north central and northeast NE reflects the zone of ascent spreading east-southeastward through the afternoon, toward the destabilizing warm sector in the wake of overnight convection across northern MO/southern IA. Though timing is still a bit uncertain, thunderstorm development appears probable late this afternoon or this evening across eastern NE and especially near the MO/IA border. Relatively long/straight hodographs, midlevel lapse rates near 7.5 C/km and MLCAPE in excess of 2000 J/kg will support supercells capable of producing large hail (1-2 inches in diameter) and damaging gusts (60-75 mph). Some upscale growth into a cluster may also occur as the storms spread east-southeastward toward IL tonight. ...OK this afternoon/evening... Strong surface heating is ongoing across central OK along a weak pre-frontal trough. Mid-upper flow will be weak this far southwest, but deep mixing with surface heating will contribute to steep low-level lapse rates and MLCAPE of 1500 J/kg or greater with minimal convective inhibition. Scattered thunderstorms are expected along this trough by mid-late afternoon, when isolated damaging downburst winds (60-75 mph) will be possible. ...New England this afternoon... To the west of a closed low over Nova Scotia, an embedded shortwave trough is rotating southward over New England with ongoing convection in southwest ME and NH. Surface heating/destabilization on the western/southern fringes of the ongoing storms will likely contribute to additional thunderstorm development this afternoon. Moderate buoyancy and steepening low-level lapse rates, as well as cool midlevel temperatures (-14 to -15 C at 500 mb), will support the potential for isolated wind damage with 45-60 mph gusts and isolated hail approaching 1 inch in diameter with multicell clusters. See MD #1557 for additional information. ...Northern Rockies this afternoon/evening... A midlevel trough will eject east-northeastward over ID/southwest MT/extreme northwest WY through this evening. Steep lapse rates and modest PW (near or less than 0.75 inches) will support high-based thunderstorm development this afternoon in the zone of ascent preceding the midlevel trough. Strong outflow gusts (50-60 mph) will be the main concern. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0256 PM CDT Thu Aug 15 2024 Valid 152000Z - 161200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM CENTRAL OK TO THE MID MS VALLEY... ...SUMMARY... Scattered severe thunderstorms are possible across parts of the Midwest through tonight. Severe gusts capable of wind damage and large hail are the primary risks with the stronger thunderstorms. A cluster of storms is ongoing across eastern Nebraska and will move into an increasingly unstable environment across Iowa later this afternoon and this evening. Have expanded the slight risk farther north into Iowa to account for this threat. See MCD #1907 for more discussion of this threat. Elsewhere, the forecast remains on track. Thunderstorm development appears imminent along a frontal boundary in Oklahoma within the next 1 to 2 hours. A somewhat similar environment exists farther southwest across portions of northwest Texas and the Texas Panhandle. However, slightly warmer temperatures around 500mb may limit updraft intensity somewhat and thus mitigate a greater severe weather threat. A few storms have developed over the higher terrain in central Idaho and southwest Montana. These storms may pose some severe wind threat as they move northeast. However, instability is quite weak (100-250 J/kg MLCAPE) and should keep any threat mostly isolated. A few large hail and severe wind gusts have occurred across New Hampshire this afternoon and a few additional strong to severe storms may develop in the region, in addition to the ongoing cluster now in northern Massachusetts. This threat should persist through early evening before waning near or shortly after sunset. ..Bentley.. 08/15/2024 .PREV DISCUSSION... /ISSUED 1124 AM CDT Thu Aug 15 2024/ ...Mid MS Valley this afternoon/evening... The remnants of overnight convection, and an associated/lead shortwave trough, are moving across southern MO/IL. Though these storms will likely weaken through midday, a diffuse outflow/differential heating zone may help focus additional thunderstorm development this afternoon. Southern MO to southern IL will be along the southern fringe of the stronger midlevel flow, where a mix of multicell clusters and possibly a supercell or two capable of producing damaging winds (60-70 mph) and isolated large hail (1-1.5 inches in diameter) will be possible later this afternoon/evening. The primary midlevel shortwave trough will progress eastward from NE/SD toward the upper MS Valley by tonight, in conjunction with a surface cold front. Weak, ongoing convection across north central and northeast NE reflects the zone of ascent spreading east-southeastward through the afternoon, toward the destabilizing warm sector in the wake of overnight convection across northern MO/southern IA. Though timing is still a bit uncertain, thunderstorm development appears probable late this afternoon or this evening across eastern NE and especially near the MO/IA border. Relatively long/straight hodographs, midlevel lapse rates near 7.5 C/km and MLCAPE in excess of 2000 J/kg will support supercells capable of producing large hail (1-2 inches in diameter) and damaging gusts (60-75 mph). Some upscale growth into a cluster may also occur as the storms spread east-southeastward toward IL tonight. ...OK this afternoon/evening... Strong surface heating is ongoing across central OK along a weak pre-frontal trough. Mid-upper flow will be weak this far southwest, but deep mixing with surface heating will contribute to steep low-level lapse rates and MLCAPE of 1500 J/kg or greater with minimal convective inhibition. Scattered thunderstorms are expected along this trough by mid-late afternoon, when isolated damaging downburst winds (60-75 mph) will be possible. ...New England this afternoon... To the west of a closed low over Nova Scotia, an embedded shortwave trough is rotating southward over New England with ongoing convection in southwest ME and NH. Surface heating/destabilization on the western/southern fringes of the ongoing storms will likely contribute to additional thunderstorm development this afternoon. Moderate buoyancy and steepening low-level lapse rates, as well as cool midlevel temperatures (-14 to -15 C at 500 mb), will support the potential for isolated wind damage with 45-60 mph gusts and isolated hail approaching 1 inch in diameter with multicell clusters. See MD #1557 for additional information. ...Northern Rockies this afternoon/evening... A midlevel trough will eject east-northeastward over ID/southwest MT/extreme northwest WY through this evening. Steep lapse rates and modest PW (near or less than 0.75 inches) will support high-based thunderstorm development this afternoon in the zone of ascent preceding the midlevel trough. Strong outflow gusts (50-60 mph) will be the main concern. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0256 PM CDT Thu Aug 15 2024 Valid 152000Z - 161200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM CENTRAL OK TO THE MID MS VALLEY... ...SUMMARY... Scattered severe thunderstorms are possible across parts of the Midwest through tonight. Severe gusts capable of wind damage and large hail are the primary risks with the stronger thunderstorms. A cluster of storms is ongoing across eastern Nebraska and will move into an increasingly unstable environment across Iowa later this afternoon and this evening. Have expanded the slight risk farther north into Iowa to account for this threat. See MCD #1907 for more discussion of this threat. Elsewhere, the forecast remains on track. Thunderstorm development appears imminent along a frontal boundary in Oklahoma within the next 1 to 2 hours. A somewhat similar environment exists farther southwest across portions of northwest Texas and the Texas Panhandle. However, slightly warmer temperatures around 500mb may limit updraft intensity somewhat and thus mitigate a greater severe weather threat. A few storms have developed over the higher terrain in central Idaho and southwest Montana. These storms may pose some severe wind threat as they move northeast. However, instability is quite weak (100-250 J/kg MLCAPE) and should keep any threat mostly isolated. A few large hail and severe wind gusts have occurred across New Hampshire this afternoon and a few additional strong to severe storms may develop in the region, in addition to the ongoing cluster now in northern Massachusetts. This threat should persist through early evening before waning near or shortly after sunset. ..Bentley.. 08/15/2024 .PREV DISCUSSION... /ISSUED 1124 AM CDT Thu Aug 15 2024/ ...Mid MS Valley this afternoon/evening... The remnants of overnight convection, and an associated/lead shortwave trough, are moving across southern MO/IL. Though these storms will likely weaken through midday, a diffuse outflow/differential heating zone may help focus additional thunderstorm development this afternoon. Southern MO to southern IL will be along the southern fringe of the stronger midlevel flow, where a mix of multicell clusters and possibly a supercell or two capable of producing damaging winds (60-70 mph) and isolated large hail (1-1.5 inches in diameter) will be possible later this afternoon/evening. The primary midlevel shortwave trough will progress eastward from NE/SD toward the upper MS Valley by tonight, in conjunction with a surface cold front. Weak, ongoing convection across north central and northeast NE reflects the zone of ascent spreading east-southeastward through the afternoon, toward the destabilizing warm sector in the wake of overnight convection across northern MO/southern IA. Though timing is still a bit uncertain, thunderstorm development appears probable late this afternoon or this evening across eastern NE and especially near the MO/IA border. Relatively long/straight hodographs, midlevel lapse rates near 7.5 C/km and MLCAPE in excess of 2000 J/kg will support supercells capable of producing large hail (1-2 inches in diameter) and damaging gusts (60-75 mph). Some upscale growth into a cluster may also occur as the storms spread east-southeastward toward IL tonight. ...OK this afternoon/evening... Strong surface heating is ongoing across central OK along a weak pre-frontal trough. Mid-upper flow will be weak this far southwest, but deep mixing with surface heating will contribute to steep low-level lapse rates and MLCAPE of 1500 J/kg or greater with minimal convective inhibition. Scattered thunderstorms are expected along this trough by mid-late afternoon, when isolated damaging downburst winds (60-75 mph) will be possible. ...New England this afternoon... To the west of a closed low over Nova Scotia, an embedded shortwave trough is rotating southward over New England with ongoing convection in southwest ME and NH. Surface heating/destabilization on the western/southern fringes of the ongoing storms will likely contribute to additional thunderstorm development this afternoon. Moderate buoyancy and steepening low-level lapse rates, as well as cool midlevel temperatures (-14 to -15 C at 500 mb), will support the potential for isolated wind damage with 45-60 mph gusts and isolated hail approaching 1 inch in diameter with multicell clusters. See MD #1557 for additional information. ...Northern Rockies this afternoon/evening... A midlevel trough will eject east-northeastward over ID/southwest MT/extreme northwest WY through this evening. Steep lapse rates and modest PW (near or less than 0.75 inches) will support high-based thunderstorm development this afternoon in the zone of ascent preceding the midlevel trough. Strong outflow gusts (50-60 mph) will be the main concern. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0256 PM CDT Thu Aug 15 2024 Valid 152000Z - 161200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM CENTRAL OK TO THE MID MS VALLEY... ...SUMMARY... Scattered severe thunderstorms are possible across parts of the Midwest through tonight. Severe gusts capable of wind damage and large hail are the primary risks with the stronger thunderstorms. A cluster of storms is ongoing across eastern Nebraska and will move into an increasingly unstable environment across Iowa later this afternoon and this evening. Have expanded the slight risk farther north into Iowa to account for this threat. See MCD #1907 for more discussion of this threat. Elsewhere, the forecast remains on track. Thunderstorm development appears imminent along a frontal boundary in Oklahoma within the next 1 to 2 hours. A somewhat similar environment exists farther southwest across portions of northwest Texas and the Texas Panhandle. However, slightly warmer temperatures around 500mb may limit updraft intensity somewhat and thus mitigate a greater severe weather threat. A few storms have developed over the higher terrain in central Idaho and southwest Montana. These storms may pose some severe wind threat as they move northeast. However, instability is quite weak (100-250 J/kg MLCAPE) and should keep any threat mostly isolated. A few large hail and severe wind gusts have occurred across New Hampshire this afternoon and a few additional strong to severe storms may develop in the region, in addition to the ongoing cluster now in northern Massachusetts. This threat should persist through early evening before waning near or shortly after sunset. ..Bentley.. 08/15/2024 .PREV DISCUSSION... /ISSUED 1124 AM CDT Thu Aug 15 2024/ ...Mid MS Valley this afternoon/evening... The remnants of overnight convection, and an associated/lead shortwave trough, are moving across southern MO/IL. Though these storms will likely weaken through midday, a diffuse outflow/differential heating zone may help focus additional thunderstorm development this afternoon. Southern MO to southern IL will be along the southern fringe of the stronger midlevel flow, where a mix of multicell clusters and possibly a supercell or two capable of producing damaging winds (60-70 mph) and isolated large hail (1-1.5 inches in diameter) will be possible later this afternoon/evening. The primary midlevel shortwave trough will progress eastward from NE/SD toward the upper MS Valley by tonight, in conjunction with a surface cold front. Weak, ongoing convection across north central and northeast NE reflects the zone of ascent spreading east-southeastward through the afternoon, toward the destabilizing warm sector in the wake of overnight convection across northern MO/southern IA. Though timing is still a bit uncertain, thunderstorm development appears probable late this afternoon or this evening across eastern NE and especially near the MO/IA border. Relatively long/straight hodographs, midlevel lapse rates near 7.5 C/km and MLCAPE in excess of 2000 J/kg will support supercells capable of producing large hail (1-2 inches in diameter) and damaging gusts (60-75 mph). Some upscale growth into a cluster may also occur as the storms spread east-southeastward toward IL tonight. ...OK this afternoon/evening... Strong surface heating is ongoing across central OK along a weak pre-frontal trough. Mid-upper flow will be weak this far southwest, but deep mixing with surface heating will contribute to steep low-level lapse rates and MLCAPE of 1500 J/kg or greater with minimal convective inhibition. Scattered thunderstorms are expected along this trough by mid-late afternoon, when isolated damaging downburst winds (60-75 mph) will be possible. ...New England this afternoon... To the west of a closed low over Nova Scotia, an embedded shortwave trough is rotating southward over New England with ongoing convection in southwest ME and NH. Surface heating/destabilization on the western/southern fringes of the ongoing storms will likely contribute to additional thunderstorm development this afternoon. Moderate buoyancy and steepening low-level lapse rates, as well as cool midlevel temperatures (-14 to -15 C at 500 mb), will support the potential for isolated wind damage with 45-60 mph gusts and isolated hail approaching 1 inch in diameter with multicell clusters. See MD #1557 for additional information. ...Northern Rockies this afternoon/evening... A midlevel trough will eject east-northeastward over ID/southwest MT/extreme northwest WY through this evening. Steep lapse rates and modest PW (near or less than 0.75 inches) will support high-based thunderstorm development this afternoon in the zone of ascent preceding the midlevel trough. Strong outflow gusts (50-60 mph) will be the main concern. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0256 PM CDT Thu Aug 15 2024 Valid 152000Z - 161200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM CENTRAL OK TO THE MID MS VALLEY... ...SUMMARY... Scattered severe thunderstorms are possible across parts of the Midwest through tonight. Severe gusts capable of wind damage and large hail are the primary risks with the stronger thunderstorms. A cluster of storms is ongoing across eastern Nebraska and will move into an increasingly unstable environment across Iowa later this afternoon and this evening. Have expanded the slight risk farther north into Iowa to account for this threat. See MCD #1907 for more discussion of this threat. Elsewhere, the forecast remains on track. Thunderstorm development appears imminent along a frontal boundary in Oklahoma within the next 1 to 2 hours. A somewhat similar environment exists farther southwest across portions of northwest Texas and the Texas Panhandle. However, slightly warmer temperatures around 500mb may limit updraft intensity somewhat and thus mitigate a greater severe weather threat. A few storms have developed over the higher terrain in central Idaho and southwest Montana. These storms may pose some severe wind threat as they move northeast. However, instability is quite weak (100-250 J/kg MLCAPE) and should keep any threat mostly isolated. A few large hail and severe wind gusts have occurred across New Hampshire this afternoon and a few additional strong to severe storms may develop in the region, in addition to the ongoing cluster now in northern Massachusetts. This threat should persist through early evening before waning near or shortly after sunset. ..Bentley.. 08/15/2024 .PREV DISCUSSION... /ISSUED 1124 AM CDT Thu Aug 15 2024/ ...Mid MS Valley this afternoon/evening... The remnants of overnight convection, and an associated/lead shortwave trough, are moving across southern MO/IL. Though these storms will likely weaken through midday, a diffuse outflow/differential heating zone may help focus additional thunderstorm development this afternoon. Southern MO to southern IL will be along the southern fringe of the stronger midlevel flow, where a mix of multicell clusters and possibly a supercell or two capable of producing damaging winds (60-70 mph) and isolated large hail (1-1.5 inches in diameter) will be possible later this afternoon/evening. The primary midlevel shortwave trough will progress eastward from NE/SD toward the upper MS Valley by tonight, in conjunction with a surface cold front. Weak, ongoing convection across north central and northeast NE reflects the zone of ascent spreading east-southeastward through the afternoon, toward the destabilizing warm sector in the wake of overnight convection across northern MO/southern IA. Though timing is still a bit uncertain, thunderstorm development appears probable late this afternoon or this evening across eastern NE and especially near the MO/IA border. Relatively long/straight hodographs, midlevel lapse rates near 7.5 C/km and MLCAPE in excess of 2000 J/kg will support supercells capable of producing large hail (1-2 inches in diameter) and damaging gusts (60-75 mph). Some upscale growth into a cluster may also occur as the storms spread east-southeastward toward IL tonight. ...OK this afternoon/evening... Strong surface heating is ongoing across central OK along a weak pre-frontal trough. Mid-upper flow will be weak this far southwest, but deep mixing with surface heating will contribute to steep low-level lapse rates and MLCAPE of 1500 J/kg or greater with minimal convective inhibition. Scattered thunderstorms are expected along this trough by mid-late afternoon, when isolated damaging downburst winds (60-75 mph) will be possible. ...New England this afternoon... To the west of a closed low over Nova Scotia, an embedded shortwave trough is rotating southward over New England with ongoing convection in southwest ME and NH. Surface heating/destabilization on the western/southern fringes of the ongoing storms will likely contribute to additional thunderstorm development this afternoon. Moderate buoyancy and steepening low-level lapse rates, as well as cool midlevel temperatures (-14 to -15 C at 500 mb), will support the potential for isolated wind damage with 45-60 mph gusts and isolated hail approaching 1 inch in diameter with multicell clusters. See MD #1557 for additional information. ...Northern Rockies this afternoon/evening... A midlevel trough will eject east-northeastward over ID/southwest MT/extreme northwest WY through this evening. Steep lapse rates and modest PW (near or less than 0.75 inches) will support high-based thunderstorm development this afternoon in the zone of ascent preceding the midlevel trough. Strong outflow gusts (50-60 mph) will be the main concern. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0256 PM CDT Thu Aug 15 2024 Valid 152000Z - 161200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM CENTRAL OK TO THE MID MS VALLEY... ...SUMMARY... Scattered severe thunderstorms are possible across parts of the Midwest through tonight. Severe gusts capable of wind damage and large hail are the primary risks with the stronger thunderstorms. A cluster of storms is ongoing across eastern Nebraska and will move into an increasingly unstable environment across Iowa later this afternoon and this evening. Have expanded the slight risk farther north into Iowa to account for this threat. See MCD #1907 for more discussion of this threat. Elsewhere, the forecast remains on track. Thunderstorm development appears imminent along a frontal boundary in Oklahoma within the next 1 to 2 hours. A somewhat similar environment exists farther southwest across portions of northwest Texas and the Texas Panhandle. However, slightly warmer temperatures around 500mb may limit updraft intensity somewhat and thus mitigate a greater severe weather threat. A few storms have developed over the higher terrain in central Idaho and southwest Montana. These storms may pose some severe wind threat as they move northeast. However, instability is quite weak (100-250 J/kg MLCAPE) and should keep any threat mostly isolated. A few large hail and severe wind gusts have occurred across New Hampshire this afternoon and a few additional strong to severe storms may develop in the region, in addition to the ongoing cluster now in northern Massachusetts. This threat should persist through early evening before waning near or shortly after sunset. ..Bentley.. 08/15/2024 .PREV DISCUSSION... /ISSUED 1124 AM CDT Thu Aug 15 2024/ ...Mid MS Valley this afternoon/evening... The remnants of overnight convection, and an associated/lead shortwave trough, are moving across southern MO/IL. Though these storms will likely weaken through midday, a diffuse outflow/differential heating zone may help focus additional thunderstorm development this afternoon. Southern MO to southern IL will be along the southern fringe of the stronger midlevel flow, where a mix of multicell clusters and possibly a supercell or two capable of producing damaging winds (60-70 mph) and isolated large hail (1-1.5 inches in diameter) will be possible later this afternoon/evening. The primary midlevel shortwave trough will progress eastward from NE/SD toward the upper MS Valley by tonight, in conjunction with a surface cold front. Weak, ongoing convection across north central and northeast NE reflects the zone of ascent spreading east-southeastward through the afternoon, toward the destabilizing warm sector in the wake of overnight convection across northern MO/southern IA. Though timing is still a bit uncertain, thunderstorm development appears probable late this afternoon or this evening across eastern NE and especially near the MO/IA border. Relatively long/straight hodographs, midlevel lapse rates near 7.5 C/km and MLCAPE in excess of 2000 J/kg will support supercells capable of producing large hail (1-2 inches in diameter) and damaging gusts (60-75 mph). Some upscale growth into a cluster may also occur as the storms spread east-southeastward toward IL tonight. ...OK this afternoon/evening... Strong surface heating is ongoing across central OK along a weak pre-frontal trough. Mid-upper flow will be weak this far southwest, but deep mixing with surface heating will contribute to steep low-level lapse rates and MLCAPE of 1500 J/kg or greater with minimal convective inhibition. Scattered thunderstorms are expected along this trough by mid-late afternoon, when isolated damaging downburst winds (60-75 mph) will be possible. ...New England this afternoon... To the west of a closed low over Nova Scotia, an embedded shortwave trough is rotating southward over New England with ongoing convection in southwest ME and NH. Surface heating/destabilization on the western/southern fringes of the ongoing storms will likely contribute to additional thunderstorm development this afternoon. Moderate buoyancy and steepening low-level lapse rates, as well as cool midlevel temperatures (-14 to -15 C at 500 mb), will support the potential for isolated wind damage with 45-60 mph gusts and isolated hail approaching 1 inch in diameter with multicell clusters. See MD #1557 for additional information. ...Northern Rockies this afternoon/evening... A midlevel trough will eject east-northeastward over ID/southwest MT/extreme northwest WY through this evening. Steep lapse rates and modest PW (near or less than 0.75 inches) will support high-based thunderstorm development this afternoon in the zone of ascent preceding the midlevel trough. Strong outflow gusts (50-60 mph) will be the main concern. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0256 PM CDT Thu Aug 15 2024 Valid 152000Z - 161200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM CENTRAL OK TO THE MID MS VALLEY... ...SUMMARY... Scattered severe thunderstorms are possible across parts of the Midwest through tonight. Severe gusts capable of wind damage and large hail are the primary risks with the stronger thunderstorms. A cluster of storms is ongoing across eastern Nebraska and will move into an increasingly unstable environment across Iowa later this afternoon and this evening. Have expanded the slight risk farther north into Iowa to account for this threat. See MCD #1907 for more discussion of this threat. Elsewhere, the forecast remains on track. Thunderstorm development appears imminent along a frontal boundary in Oklahoma within the next 1 to 2 hours. A somewhat similar environment exists farther southwest across portions of northwest Texas and the Texas Panhandle. However, slightly warmer temperatures around 500mb may limit updraft intensity somewhat and thus mitigate a greater severe weather threat. A few storms have developed over the higher terrain in central Idaho and southwest Montana. These storms may pose some severe wind threat as they move northeast. However, instability is quite weak (100-250 J/kg MLCAPE) and should keep any threat mostly isolated. A few large hail and severe wind gusts have occurred across New Hampshire this afternoon and a few additional strong to severe storms may develop in the region, in addition to the ongoing cluster now in northern Massachusetts. This threat should persist through early evening before waning near or shortly after sunset. ..Bentley.. 08/15/2024 .PREV DISCUSSION... /ISSUED 1124 AM CDT Thu Aug 15 2024/ ...Mid MS Valley this afternoon/evening... The remnants of overnight convection, and an associated/lead shortwave trough, are moving across southern MO/IL. Though these storms will likely weaken through midday, a diffuse outflow/differential heating zone may help focus additional thunderstorm development this afternoon. Southern MO to southern IL will be along the southern fringe of the stronger midlevel flow, where a mix of multicell clusters and possibly a supercell or two capable of producing damaging winds (60-70 mph) and isolated large hail (1-1.5 inches in diameter) will be possible later this afternoon/evening. The primary midlevel shortwave trough will progress eastward from NE/SD toward the upper MS Valley by tonight, in conjunction with a surface cold front. Weak, ongoing convection across north central and northeast NE reflects the zone of ascent spreading east-southeastward through the afternoon, toward the destabilizing warm sector in the wake of overnight convection across northern MO/southern IA. Though timing is still a bit uncertain, thunderstorm development appears probable late this afternoon or this evening across eastern NE and especially near the MO/IA border. Relatively long/straight hodographs, midlevel lapse rates near 7.5 C/km and MLCAPE in excess of 2000 J/kg will support supercells capable of producing large hail (1-2 inches in diameter) and damaging gusts (60-75 mph). Some upscale growth into a cluster may also occur as the storms spread east-southeastward toward IL tonight. ...OK this afternoon/evening... Strong surface heating is ongoing across central OK along a weak pre-frontal trough. Mid-upper flow will be weak this far southwest, but deep mixing with surface heating will contribute to steep low-level lapse rates and MLCAPE of 1500 J/kg or greater with minimal convective inhibition. Scattered thunderstorms are expected along this trough by mid-late afternoon, when isolated damaging downburst winds (60-75 mph) will be possible. ...New England this afternoon... To the west of a closed low over Nova Scotia, an embedded shortwave trough is rotating southward over New England with ongoing convection in southwest ME and NH. Surface heating/destabilization on the western/southern fringes of the ongoing storms will likely contribute to additional thunderstorm development this afternoon. Moderate buoyancy and steepening low-level lapse rates, as well as cool midlevel temperatures (-14 to -15 C at 500 mb), will support the potential for isolated wind damage with 45-60 mph gusts and isolated hail approaching 1 inch in diameter with multicell clusters. See MD #1557 for additional information. ...Northern Rockies this afternoon/evening... A midlevel trough will eject east-northeastward over ID/southwest MT/extreme northwest WY through this evening. Steep lapse rates and modest PW (near or less than 0.75 inches) will support high-based thunderstorm development this afternoon in the zone of ascent preceding the midlevel trough. Strong outflow gusts (50-60 mph) will be the main concern. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0256 PM CDT Thu Aug 15 2024 Valid 152000Z - 161200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM CENTRAL OK TO THE MID MS VALLEY... ...SUMMARY... Scattered severe thunderstorms are possible across parts of the Midwest through tonight. Severe gusts capable of wind damage and large hail are the primary risks with the stronger thunderstorms. A cluster of storms is ongoing across eastern Nebraska and will move into an increasingly unstable environment across Iowa later this afternoon and this evening. Have expanded the slight risk farther north into Iowa to account for this threat. See MCD #1907 for more discussion of this threat. Elsewhere, the forecast remains on track. Thunderstorm development appears imminent along a frontal boundary in Oklahoma within the next 1 to 2 hours. A somewhat similar environment exists farther southwest across portions of northwest Texas and the Texas Panhandle. However, slightly warmer temperatures around 500mb may limit updraft intensity somewhat and thus mitigate a greater severe weather threat. A few storms have developed over the higher terrain in central Idaho and southwest Montana. These storms may pose some severe wind threat as they move northeast. However, instability is quite weak (100-250 J/kg MLCAPE) and should keep any threat mostly isolated. A few large hail and severe wind gusts have occurred across New Hampshire this afternoon and a few additional strong to severe storms may develop in the region, in addition to the ongoing cluster now in northern Massachusetts. This threat should persist through early evening before waning near or shortly after sunset. ..Bentley.. 08/15/2024 .PREV DISCUSSION... /ISSUED 1124 AM CDT Thu Aug 15 2024/ ...Mid MS Valley this afternoon/evening... The remnants of overnight convection, and an associated/lead shortwave trough, are moving across southern MO/IL. Though these storms will likely weaken through midday, a diffuse outflow/differential heating zone may help focus additional thunderstorm development this afternoon. Southern MO to southern IL will be along the southern fringe of the stronger midlevel flow, where a mix of multicell clusters and possibly a supercell or two capable of producing damaging winds (60-70 mph) and isolated large hail (1-1.5 inches in diameter) will be possible later this afternoon/evening. The primary midlevel shortwave trough will progress eastward from NE/SD toward the upper MS Valley by tonight, in conjunction with a surface cold front. Weak, ongoing convection across north central and northeast NE reflects the zone of ascent spreading east-southeastward through the afternoon, toward the destabilizing warm sector in the wake of overnight convection across northern MO/southern IA. Though timing is still a bit uncertain, thunderstorm development appears probable late this afternoon or this evening across eastern NE and especially near the MO/IA border. Relatively long/straight hodographs, midlevel lapse rates near 7.5 C/km and MLCAPE in excess of 2000 J/kg will support supercells capable of producing large hail (1-2 inches in diameter) and damaging gusts (60-75 mph). Some upscale growth into a cluster may also occur as the storms spread east-southeastward toward IL tonight. ...OK this afternoon/evening... Strong surface heating is ongoing across central OK along a weak pre-frontal trough. Mid-upper flow will be weak this far southwest, but deep mixing with surface heating will contribute to steep low-level lapse rates and MLCAPE of 1500 J/kg or greater with minimal convective inhibition. Scattered thunderstorms are expected along this trough by mid-late afternoon, when isolated damaging downburst winds (60-75 mph) will be possible. ...New England this afternoon... To the west of a closed low over Nova Scotia, an embedded shortwave trough is rotating southward over New England with ongoing convection in southwest ME and NH. Surface heating/destabilization on the western/southern fringes of the ongoing storms will likely contribute to additional thunderstorm development this afternoon. Moderate buoyancy and steepening low-level lapse rates, as well as cool midlevel temperatures (-14 to -15 C at 500 mb), will support the potential for isolated wind damage with 45-60 mph gusts and isolated hail approaching 1 inch in diameter with multicell clusters. See MD #1557 for additional information. ...Northern Rockies this afternoon/evening... A midlevel trough will eject east-northeastward over ID/southwest MT/extreme northwest WY through this evening. Steep lapse rates and modest PW (near or less than 0.75 inches) will support high-based thunderstorm development this afternoon in the zone of ascent preceding the midlevel trough. Strong outflow gusts (50-60 mph) will be the main concern. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0256 PM CDT Thu Aug 15 2024 Valid 152000Z - 161200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM CENTRAL OK TO THE MID MS VALLEY... ...SUMMARY... Scattered severe thunderstorms are possible across parts of the Midwest through tonight. Severe gusts capable of wind damage and large hail are the primary risks with the stronger thunderstorms. A cluster of storms is ongoing across eastern Nebraska and will move into an increasingly unstable environment across Iowa later this afternoon and this evening. Have expanded the slight risk farther north into Iowa to account for this threat. See MCD #1907 for more discussion of this threat. Elsewhere, the forecast remains on track. Thunderstorm development appears imminent along a frontal boundary in Oklahoma within the next 1 to 2 hours. A somewhat similar environment exists farther southwest across portions of northwest Texas and the Texas Panhandle. However, slightly warmer temperatures around 500mb may limit updraft intensity somewhat and thus mitigate a greater severe weather threat. A few storms have developed over the higher terrain in central Idaho and southwest Montana. These storms may pose some severe wind threat as they move northeast. However, instability is quite weak (100-250 J/kg MLCAPE) and should keep any threat mostly isolated. A few large hail and severe wind gusts have occurred across New Hampshire this afternoon and a few additional strong to severe storms may develop in the region, in addition to the ongoing cluster now in northern Massachusetts. This threat should persist through early evening before waning near or shortly after sunset. ..Bentley.. 08/15/2024 .PREV DISCUSSION... /ISSUED 1124 AM CDT Thu Aug 15 2024/ ...Mid MS Valley this afternoon/evening... The remnants of overnight convection, and an associated/lead shortwave trough, are moving across southern MO/IL. Though these storms will likely weaken through midday, a diffuse outflow/differential heating zone may help focus additional thunderstorm development this afternoon. Southern MO to southern IL will be along the southern fringe of the stronger midlevel flow, where a mix of multicell clusters and possibly a supercell or two capable of producing damaging winds (60-70 mph) and isolated large hail (1-1.5 inches in diameter) will be possible later this afternoon/evening. The primary midlevel shortwave trough will progress eastward from NE/SD toward the upper MS Valley by tonight, in conjunction with a surface cold front. Weak, ongoing convection across north central and northeast NE reflects the zone of ascent spreading east-southeastward through the afternoon, toward the destabilizing warm sector in the wake of overnight convection across northern MO/southern IA. Though timing is still a bit uncertain, thunderstorm development appears probable late this afternoon or this evening across eastern NE and especially near the MO/IA border. Relatively long/straight hodographs, midlevel lapse rates near 7.5 C/km and MLCAPE in excess of 2000 J/kg will support supercells capable of producing large hail (1-2 inches in diameter) and damaging gusts (60-75 mph). Some upscale growth into a cluster may also occur as the storms spread east-southeastward toward IL tonight. ...OK this afternoon/evening... Strong surface heating is ongoing across central OK along a weak pre-frontal trough. Mid-upper flow will be weak this far southwest, but deep mixing with surface heating will contribute to steep low-level lapse rates and MLCAPE of 1500 J/kg or greater with minimal convective inhibition. Scattered thunderstorms are expected along this trough by mid-late afternoon, when isolated damaging downburst winds (60-75 mph) will be possible. ...New England this afternoon... To the west of a closed low over Nova Scotia, an embedded shortwave trough is rotating southward over New England with ongoing convection in southwest ME and NH. Surface heating/destabilization on the western/southern fringes of the ongoing storms will likely contribute to additional thunderstorm development this afternoon. Moderate buoyancy and steepening low-level lapse rates, as well as cool midlevel temperatures (-14 to -15 C at 500 mb), will support the potential for isolated wind damage with 45-60 mph gusts and isolated hail approaching 1 inch in diameter with multicell clusters. See MD #1557 for additional information. ...Northern Rockies this afternoon/evening... A midlevel trough will eject east-northeastward over ID/southwest MT/extreme northwest WY through this evening. Steep lapse rates and modest PW (near or less than 0.75 inches) will support high-based thunderstorm development this afternoon in the zone of ascent preceding the midlevel trough. Strong outflow gusts (50-60 mph) will be the main concern. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0256 PM CDT Thu Aug 15 2024 Valid 152000Z - 161200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM CENTRAL OK TO THE MID MS VALLEY... ...SUMMARY... Scattered severe thunderstorms are possible across parts of the Midwest through tonight. Severe gusts capable of wind damage and large hail are the primary risks with the stronger thunderstorms. A cluster of storms is ongoing across eastern Nebraska and will move into an increasingly unstable environment across Iowa later this afternoon and this evening. Have expanded the slight risk farther north into Iowa to account for this threat. See MCD #1907 for more discussion of this threat. Elsewhere, the forecast remains on track. Thunderstorm development appears imminent along a frontal boundary in Oklahoma within the next 1 to 2 hours. A somewhat similar environment exists farther southwest across portions of northwest Texas and the Texas Panhandle. However, slightly warmer temperatures around 500mb may limit updraft intensity somewhat and thus mitigate a greater severe weather threat. A few storms have developed over the higher terrain in central Idaho and southwest Montana. These storms may pose some severe wind threat as they move northeast. However, instability is quite weak (100-250 J/kg MLCAPE) and should keep any threat mostly isolated. A few large hail and severe wind gusts have occurred across New Hampshire this afternoon and a few additional strong to severe storms may develop in the region, in addition to the ongoing cluster now in northern Massachusetts. This threat should persist through early evening before waning near or shortly after sunset. ..Bentley.. 08/15/2024 .PREV DISCUSSION... /ISSUED 1124 AM CDT Thu Aug 15 2024/ ...Mid MS Valley this afternoon/evening... The remnants of overnight convection, and an associated/lead shortwave trough, are moving across southern MO/IL. Though these storms will likely weaken through midday, a diffuse outflow/differential heating zone may help focus additional thunderstorm development this afternoon. Southern MO to southern IL will be along the southern fringe of the stronger midlevel flow, where a mix of multicell clusters and possibly a supercell or two capable of producing damaging winds (60-70 mph) and isolated large hail (1-1.5 inches in diameter) will be possible later this afternoon/evening. The primary midlevel shortwave trough will progress eastward from NE/SD toward the upper MS Valley by tonight, in conjunction with a surface cold front. Weak, ongoing convection across north central and northeast NE reflects the zone of ascent spreading east-southeastward through the afternoon, toward the destabilizing warm sector in the wake of overnight convection across northern MO/southern IA. Though timing is still a bit uncertain, thunderstorm development appears probable late this afternoon or this evening across eastern NE and especially near the MO/IA border. Relatively long/straight hodographs, midlevel lapse rates near 7.5 C/km and MLCAPE in excess of 2000 J/kg will support supercells capable of producing large hail (1-2 inches in diameter) and damaging gusts (60-75 mph). Some upscale growth into a cluster may also occur as the storms spread east-southeastward toward IL tonight. ...OK this afternoon/evening... Strong surface heating is ongoing across central OK along a weak pre-frontal trough. Mid-upper flow will be weak this far southwest, but deep mixing with surface heating will contribute to steep low-level lapse rates and MLCAPE of 1500 J/kg or greater with minimal convective inhibition. Scattered thunderstorms are expected along this trough by mid-late afternoon, when isolated damaging downburst winds (60-75 mph) will be possible. ...New England this afternoon... To the west of a closed low over Nova Scotia, an embedded shortwave trough is rotating southward over New England with ongoing convection in southwest ME and NH. Surface heating/destabilization on the western/southern fringes of the ongoing storms will likely contribute to additional thunderstorm development this afternoon. Moderate buoyancy and steepening low-level lapse rates, as well as cool midlevel temperatures (-14 to -15 C at 500 mb), will support the potential for isolated wind damage with 45-60 mph gusts and isolated hail approaching 1 inch in diameter with multicell clusters. See MD #1557 for additional information. ...Northern Rockies this afternoon/evening... A midlevel trough will eject east-northeastward over ID/southwest MT/extreme northwest WY through this evening. Steep lapse rates and modest PW (near or less than 0.75 inches) will support high-based thunderstorm development this afternoon in the zone of ascent preceding the midlevel trough. Strong outflow gusts (50-60 mph) will be the main concern. Read more

SPC 1930Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0224 PM CDT Thu Aug 15 2024 Valid 171200Z - 181200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS IN PARTS OF THE EASTERN U.S. AND THE PACIFIC NORTHWEST... ...SUMMARY... Isolated severe thunderstorms are possible, mainly Saturday afternoon and evening, from the Lower Great Lakes to the Mid/Deep South, and separately across a portion of the Pacific Northwest. ...Lower Great Lakes to the Mid/Deep South... Much of the broad level 1-MRGL risk area has remain unchanged, with a minor expansion across parts of the Mid-South. A slow-moving mid/upper trough should continue east across the Great Lakes vicinity through early Sunday. An occluded surface cyclone over Lower MI should drift into southern ON. A weak cold front will arc to the south over the Upper OH Valley and trail southwest to west across the Mid-South to the KS-OK border area. Along this baroclinic zone, ongoing convection at 12Z Saturday appears most probable over the Ozarks to Mid-South vicinity. It is plausible this activity may intensify, perhaps aided by an attendant MCV generated on D2, as downstream diurnal destabilization occurs in parts of the Mid to Deep South. This region will lie in the gradient of mid-level flow enhancement (outside of any MCV influence) that would aid in semi-organized multicell clustering, with a threat for sporadic damaging winds. Farther north and east, deep-layer flow should be nearly unidirectional with moderate 700-500 mb westerlies. This will foster potential for multiple multicell clusters over a relatively broad warm sector across the OH Valley to the Lower Great Lakes and the Appalachians. Mid-level lapse rates will be weaker with eastern extent, and overall MLCAPE values should tend to be moderate from 1000-2500 J/kg. At least localized damaging winds will be possible across a broad swath of the eastern CONUS. Confidence remains too low at this time in highlighting more focused corridors of greater damaging wind potential. ...Pacific Northwest... A pronounced shortwave impulse, embedded within a broader mid/upper trough, should approach the northern CA and OR coast on Saturday. A strengthening mid to upper jetlet should become centered across northern CA and the Sierra NV Range. Within the exit region of this meridional flow regime, scattered late-afternoon and evening thunderstorms should be focused from south to north across the Cascade Range. While buoyancy should remain weak, steepening mid to low-level lapse rates will support a threat for a few organized high-based cells/clusters. Isolated severe wind gusts should be the main hazard. ..Grams.. 08/15/2024 Read more

SPC 1930Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0224 PM CDT Thu Aug 15 2024 Valid 171200Z - 181200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS IN PARTS OF THE EASTERN U.S. AND THE PACIFIC NORTHWEST... ...SUMMARY... Isolated severe thunderstorms are possible, mainly Saturday afternoon and evening, from the Lower Great Lakes to the Mid/Deep South, and separately across a portion of the Pacific Northwest. ...Lower Great Lakes to the Mid/Deep South... Much of the broad level 1-MRGL risk area has remain unchanged, with a minor expansion across parts of the Mid-South. A slow-moving mid/upper trough should continue east across the Great Lakes vicinity through early Sunday. An occluded surface cyclone over Lower MI should drift into southern ON. A weak cold front will arc to the south over the Upper OH Valley and trail southwest to west across the Mid-South to the KS-OK border area. Along this baroclinic zone, ongoing convection at 12Z Saturday appears most probable over the Ozarks to Mid-South vicinity. It is plausible this activity may intensify, perhaps aided by an attendant MCV generated on D2, as downstream diurnal destabilization occurs in parts of the Mid to Deep South. This region will lie in the gradient of mid-level flow enhancement (outside of any MCV influence) that would aid in semi-organized multicell clustering, with a threat for sporadic damaging winds. Farther north and east, deep-layer flow should be nearly unidirectional with moderate 700-500 mb westerlies. This will foster potential for multiple multicell clusters over a relatively broad warm sector across the OH Valley to the Lower Great Lakes and the Appalachians. Mid-level lapse rates will be weaker with eastern extent, and overall MLCAPE values should tend to be moderate from 1000-2500 J/kg. At least localized damaging winds will be possible across a broad swath of the eastern CONUS. Confidence remains too low at this time in highlighting more focused corridors of greater damaging wind potential. ...Pacific Northwest... A pronounced shortwave impulse, embedded within a broader mid/upper trough, should approach the northern CA and OR coast on Saturday. A strengthening mid to upper jetlet should become centered across northern CA and the Sierra NV Range. Within the exit region of this meridional flow regime, scattered late-afternoon and evening thunderstorms should be focused from south to north across the Cascade Range. While buoyancy should remain weak, steepening mid to low-level lapse rates will support a threat for a few organized high-based cells/clusters. Isolated severe wind gusts should be the main hazard. ..Grams.. 08/15/2024 Read more

SPC 1930Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0224 PM CDT Thu Aug 15 2024 Valid 171200Z - 181200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS IN PARTS OF THE EASTERN U.S. AND THE PACIFIC NORTHWEST... ...SUMMARY... Isolated severe thunderstorms are possible, mainly Saturday afternoon and evening, from the Lower Great Lakes to the Mid/Deep South, and separately across a portion of the Pacific Northwest. ...Lower Great Lakes to the Mid/Deep South... Much of the broad level 1-MRGL risk area has remain unchanged, with a minor expansion across parts of the Mid-South. A slow-moving mid/upper trough should continue east across the Great Lakes vicinity through early Sunday. An occluded surface cyclone over Lower MI should drift into southern ON. A weak cold front will arc to the south over the Upper OH Valley and trail southwest to west across the Mid-South to the KS-OK border area. Along this baroclinic zone, ongoing convection at 12Z Saturday appears most probable over the Ozarks to Mid-South vicinity. It is plausible this activity may intensify, perhaps aided by an attendant MCV generated on D2, as downstream diurnal destabilization occurs in parts of the Mid to Deep South. This region will lie in the gradient of mid-level flow enhancement (outside of any MCV influence) that would aid in semi-organized multicell clustering, with a threat for sporadic damaging winds. Farther north and east, deep-layer flow should be nearly unidirectional with moderate 700-500 mb westerlies. This will foster potential for multiple multicell clusters over a relatively broad warm sector across the OH Valley to the Lower Great Lakes and the Appalachians. Mid-level lapse rates will be weaker with eastern extent, and overall MLCAPE values should tend to be moderate from 1000-2500 J/kg. At least localized damaging winds will be possible across a broad swath of the eastern CONUS. Confidence remains too low at this time in highlighting more focused corridors of greater damaging wind potential. ...Pacific Northwest... A pronounced shortwave impulse, embedded within a broader mid/upper trough, should approach the northern CA and OR coast on Saturday. A strengthening mid to upper jetlet should become centered across northern CA and the Sierra NV Range. Within the exit region of this meridional flow regime, scattered late-afternoon and evening thunderstorms should be focused from south to north across the Cascade Range. While buoyancy should remain weak, steepening mid to low-level lapse rates will support a threat for a few organized high-based cells/clusters. Isolated severe wind gusts should be the main hazard. ..Grams.. 08/15/2024 Read more

SPC 1930Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0224 PM CDT Thu Aug 15 2024 Valid 171200Z - 181200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS IN PARTS OF THE EASTERN U.S. AND THE PACIFIC NORTHWEST... ...SUMMARY... Isolated severe thunderstorms are possible, mainly Saturday afternoon and evening, from the Lower Great Lakes to the Mid/Deep South, and separately across a portion of the Pacific Northwest. ...Lower Great Lakes to the Mid/Deep South... Much of the broad level 1-MRGL risk area has remain unchanged, with a minor expansion across parts of the Mid-South. A slow-moving mid/upper trough should continue east across the Great Lakes vicinity through early Sunday. An occluded surface cyclone over Lower MI should drift into southern ON. A weak cold front will arc to the south over the Upper OH Valley and trail southwest to west across the Mid-South to the KS-OK border area. Along this baroclinic zone, ongoing convection at 12Z Saturday appears most probable over the Ozarks to Mid-South vicinity. It is plausible this activity may intensify, perhaps aided by an attendant MCV generated on D2, as downstream diurnal destabilization occurs in parts of the Mid to Deep South. This region will lie in the gradient of mid-level flow enhancement (outside of any MCV influence) that would aid in semi-organized multicell clustering, with a threat for sporadic damaging winds. Farther north and east, deep-layer flow should be nearly unidirectional with moderate 700-500 mb westerlies. This will foster potential for multiple multicell clusters over a relatively broad warm sector across the OH Valley to the Lower Great Lakes and the Appalachians. Mid-level lapse rates will be weaker with eastern extent, and overall MLCAPE values should tend to be moderate from 1000-2500 J/kg. At least localized damaging winds will be possible across a broad swath of the eastern CONUS. Confidence remains too low at this time in highlighting more focused corridors of greater damaging wind potential. ...Pacific Northwest... A pronounced shortwave impulse, embedded within a broader mid/upper trough, should approach the northern CA and OR coast on Saturday. A strengthening mid to upper jetlet should become centered across northern CA and the Sierra NV Range. Within the exit region of this meridional flow regime, scattered late-afternoon and evening thunderstorms should be focused from south to north across the Cascade Range. While buoyancy should remain weak, steepening mid to low-level lapse rates will support a threat for a few organized high-based cells/clusters. Isolated severe wind gusts should be the main hazard. ..Grams.. 08/15/2024 Read more

SPC 1930Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0224 PM CDT Thu Aug 15 2024 Valid 171200Z - 181200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS IN PARTS OF THE EASTERN U.S. AND THE PACIFIC NORTHWEST... ...SUMMARY... Isolated severe thunderstorms are possible, mainly Saturday afternoon and evening, from the Lower Great Lakes to the Mid/Deep South, and separately across a portion of the Pacific Northwest. ...Lower Great Lakes to the Mid/Deep South... Much of the broad level 1-MRGL risk area has remain unchanged, with a minor expansion across parts of the Mid-South. A slow-moving mid/upper trough should continue east across the Great Lakes vicinity through early Sunday. An occluded surface cyclone over Lower MI should drift into southern ON. A weak cold front will arc to the south over the Upper OH Valley and trail southwest to west across the Mid-South to the KS-OK border area. Along this baroclinic zone, ongoing convection at 12Z Saturday appears most probable over the Ozarks to Mid-South vicinity. It is plausible this activity may intensify, perhaps aided by an attendant MCV generated on D2, as downstream diurnal destabilization occurs in parts of the Mid to Deep South. This region will lie in the gradient of mid-level flow enhancement (outside of any MCV influence) that would aid in semi-organized multicell clustering, with a threat for sporadic damaging winds. Farther north and east, deep-layer flow should be nearly unidirectional with moderate 700-500 mb westerlies. This will foster potential for multiple multicell clusters over a relatively broad warm sector across the OH Valley to the Lower Great Lakes and the Appalachians. Mid-level lapse rates will be weaker with eastern extent, and overall MLCAPE values should tend to be moderate from 1000-2500 J/kg. At least localized damaging winds will be possible across a broad swath of the eastern CONUS. Confidence remains too low at this time in highlighting more focused corridors of greater damaging wind potential. ...Pacific Northwest... A pronounced shortwave impulse, embedded within a broader mid/upper trough, should approach the northern CA and OR coast on Saturday. A strengthening mid to upper jetlet should become centered across northern CA and the Sierra NV Range. Within the exit region of this meridional flow regime, scattered late-afternoon and evening thunderstorms should be focused from south to north across the Cascade Range. While buoyancy should remain weak, steepening mid to low-level lapse rates will support a threat for a few organized high-based cells/clusters. Isolated severe wind gusts should be the main hazard. ..Grams.. 08/15/2024 Read more

SPC 1930Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0224 PM CDT Thu Aug 15 2024 Valid 171200Z - 181200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS IN PARTS OF THE EASTERN U.S. AND THE PACIFIC NORTHWEST... ...SUMMARY... Isolated severe thunderstorms are possible, mainly Saturday afternoon and evening, from the Lower Great Lakes to the Mid/Deep South, and separately across a portion of the Pacific Northwest. ...Lower Great Lakes to the Mid/Deep South... Much of the broad level 1-MRGL risk area has remain unchanged, with a minor expansion across parts of the Mid-South. A slow-moving mid/upper trough should continue east across the Great Lakes vicinity through early Sunday. An occluded surface cyclone over Lower MI should drift into southern ON. A weak cold front will arc to the south over the Upper OH Valley and trail southwest to west across the Mid-South to the KS-OK border area. Along this baroclinic zone, ongoing convection at 12Z Saturday appears most probable over the Ozarks to Mid-South vicinity. It is plausible this activity may intensify, perhaps aided by an attendant MCV generated on D2, as downstream diurnal destabilization occurs in parts of the Mid to Deep South. This region will lie in the gradient of mid-level flow enhancement (outside of any MCV influence) that would aid in semi-organized multicell clustering, with a threat for sporadic damaging winds. Farther north and east, deep-layer flow should be nearly unidirectional with moderate 700-500 mb westerlies. This will foster potential for multiple multicell clusters over a relatively broad warm sector across the OH Valley to the Lower Great Lakes and the Appalachians. Mid-level lapse rates will be weaker with eastern extent, and overall MLCAPE values should tend to be moderate from 1000-2500 J/kg. At least localized damaging winds will be possible across a broad swath of the eastern CONUS. Confidence remains too low at this time in highlighting more focused corridors of greater damaging wind potential. ...Pacific Northwest... A pronounced shortwave impulse, embedded within a broader mid/upper trough, should approach the northern CA and OR coast on Saturday. A strengthening mid to upper jetlet should become centered across northern CA and the Sierra NV Range. Within the exit region of this meridional flow regime, scattered late-afternoon and evening thunderstorms should be focused from south to north across the Cascade Range. While buoyancy should remain weak, steepening mid to low-level lapse rates will support a threat for a few organized high-based cells/clusters. Isolated severe wind gusts should be the main hazard. ..Grams.. 08/15/2024 Read more