Severe Storms

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0307 PM CDT Thu Aug 15 2024 Valid 171200Z - 231200Z Fire weather concerns will remain focused across the Great Basin through the forecast period, and will be greatest over the weekend across western to central NV. Long-range ensemble guidance continues to show a gradual transition to a highly amplified upper-level regime through the upcoming weekend with troughing along the West Coast and ridging over the south-central CONUS. Disturbances propagating through the West Coast trough will bring breezy conditions to the Great Basin where precipitation chances will be minimal through next week. Hot/dry conditions are expected to persist across central to western TX where fire activity has increased amid steadily-drying fuels. ...D3/Sat to D5/Mon - Great Basin... Confidence in critical fire weather conditions continues to increase for D3/Saturday across the western Great Basin. Ensemble guidance shows a reasonably strong signal for 20+ mph winds in the lee of the Sierra Nevada as a mid-level perturbation propagates through the West Coast trough. Fuel conditions are favorable for fire spread after multiple days of single-digit RH and minimal rainfall. Downslope warming/drying should maintain widespread RH reductions into the single digits and low teens coincident with 15-25 mph winds. 70% risk probabilities have been introduced within the broader risk area where confidence the potential for sustained 20+ mph winds and gusts upwards of 30-35 mph appears greatest. After D3/Saturday, mid-level flow will abate in the wake of the upper disturbance, but lingering 30-40 knot flow should maintain breezy downslope conditions with the potential for elevated to critical fire weather conditions through at least D4/Sunday and D5/Monday. ...Texas... Long-range guidance continues to show strong consensus on persistent afternoon high temperatures well above 100-105 F through the forecast period across central to western TX. This places temperatures well above the 90th percentile for mid-August with some locations approaching record daytime highs. The anomalous heat is driving rapid curing/drying of grasses and shrubs across the region, which has resulted in increased fire activity in recent days. Fuels will become increasingly available as the heat lingers well into next week; however, the building upper ridge will modulate surface pressure gradients and limit the potential for widespread windy conditions. Recent ensemble guidance continues to show very limited potential for sustained winds above 20 mph for central/western TX, but trends will continue to be monitored. ..Moore.. 08/15/2024 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0307 PM CDT Thu Aug 15 2024 Valid 171200Z - 231200Z Fire weather concerns will remain focused across the Great Basin through the forecast period, and will be greatest over the weekend across western to central NV. Long-range ensemble guidance continues to show a gradual transition to a highly amplified upper-level regime through the upcoming weekend with troughing along the West Coast and ridging over the south-central CONUS. Disturbances propagating through the West Coast trough will bring breezy conditions to the Great Basin where precipitation chances will be minimal through next week. Hot/dry conditions are expected to persist across central to western TX where fire activity has increased amid steadily-drying fuels. ...D3/Sat to D5/Mon - Great Basin... Confidence in critical fire weather conditions continues to increase for D3/Saturday across the western Great Basin. Ensemble guidance shows a reasonably strong signal for 20+ mph winds in the lee of the Sierra Nevada as a mid-level perturbation propagates through the West Coast trough. Fuel conditions are favorable for fire spread after multiple days of single-digit RH and minimal rainfall. Downslope warming/drying should maintain widespread RH reductions into the single digits and low teens coincident with 15-25 mph winds. 70% risk probabilities have been introduced within the broader risk area where confidence the potential for sustained 20+ mph winds and gusts upwards of 30-35 mph appears greatest. After D3/Saturday, mid-level flow will abate in the wake of the upper disturbance, but lingering 30-40 knot flow should maintain breezy downslope conditions with the potential for elevated to critical fire weather conditions through at least D4/Sunday and D5/Monday. ...Texas... Long-range guidance continues to show strong consensus on persistent afternoon high temperatures well above 100-105 F through the forecast period across central to western TX. This places temperatures well above the 90th percentile for mid-August with some locations approaching record daytime highs. The anomalous heat is driving rapid curing/drying of grasses and shrubs across the region, which has resulted in increased fire activity in recent days. Fuels will become increasingly available as the heat lingers well into next week; however, the building upper ridge will modulate surface pressure gradients and limit the potential for widespread windy conditions. Recent ensemble guidance continues to show very limited potential for sustained winds above 20 mph for central/western TX, but trends will continue to be monitored. ..Moore.. 08/15/2024 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0307 PM CDT Thu Aug 15 2024 Valid 171200Z - 231200Z Fire weather concerns will remain focused across the Great Basin through the forecast period, and will be greatest over the weekend across western to central NV. Long-range ensemble guidance continues to show a gradual transition to a highly amplified upper-level regime through the upcoming weekend with troughing along the West Coast and ridging over the south-central CONUS. Disturbances propagating through the West Coast trough will bring breezy conditions to the Great Basin where precipitation chances will be minimal through next week. Hot/dry conditions are expected to persist across central to western TX where fire activity has increased amid steadily-drying fuels. ...D3/Sat to D5/Mon - Great Basin... Confidence in critical fire weather conditions continues to increase for D3/Saturday across the western Great Basin. Ensemble guidance shows a reasonably strong signal for 20+ mph winds in the lee of the Sierra Nevada as a mid-level perturbation propagates through the West Coast trough. Fuel conditions are favorable for fire spread after multiple days of single-digit RH and minimal rainfall. Downslope warming/drying should maintain widespread RH reductions into the single digits and low teens coincident with 15-25 mph winds. 70% risk probabilities have been introduced within the broader risk area where confidence the potential for sustained 20+ mph winds and gusts upwards of 30-35 mph appears greatest. After D3/Saturday, mid-level flow will abate in the wake of the upper disturbance, but lingering 30-40 knot flow should maintain breezy downslope conditions with the potential for elevated to critical fire weather conditions through at least D4/Sunday and D5/Monday. ...Texas... Long-range guidance continues to show strong consensus on persistent afternoon high temperatures well above 100-105 F through the forecast period across central to western TX. This places temperatures well above the 90th percentile for mid-August with some locations approaching record daytime highs. The anomalous heat is driving rapid curing/drying of grasses and shrubs across the region, which has resulted in increased fire activity in recent days. Fuels will become increasingly available as the heat lingers well into next week; however, the building upper ridge will modulate surface pressure gradients and limit the potential for widespread windy conditions. Recent ensemble guidance continues to show very limited potential for sustained winds above 20 mph for central/western TX, but trends will continue to be monitored. ..Moore.. 08/15/2024 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

MD 1907 CONCERNING SEVERE POTENTIAL...WATCH POSSIBLE FOR PARTS OF EASTERN NEBRASKA INTO WESTERN IOWA
Mesoscale Discussion 1907 NWS Storm Prediction Center Norman OK 0114 PM CDT Thu Aug 15 2024 Areas affected...parts of eastern Nebraska into western Iowa Concerning...Severe potential...Watch possible Valid 151814Z - 152015Z Probability of Watch Issuance...40 percent SUMMARY...A developing cluster of thunderstorms, with strongest storms gradually consolidating on its southern flank, may continue to pose a risk for severe hail and a few strong surface gusts across the Interstate 80 corridor of western Iowa and adjacent eastern Nebraska through 4-5 PM CDT. DISCUSSION...Thunderstorm activity has undergone a recent increase near the Norfolk vicinity of northeastern Nebraska. This is occurring in the presence of weak low-level cold advection, to the west of a surface trough axis shifting southeastward through the central Great Plains and mid to lower Missouri Valley region. However, the boundary-layer remains relatively moist, and appears supportive of CAPE on the order of 1000-1500 J/kg, beneath the leading edge of a -10 to -12C 500 mb cold pool, associated with a notable mid-level perturbation pivoting southeastward and eastward across southern portions of the mid Missouri Valley. Generally within the exit region of a 40-70+ kt westerly jet streak in the 500-300 mb layer, deep-layer shear appears sufficient for supercell structures with potential to produce severe hail. With continuing insolation in advance of activity, it is possible that vigorous thunderstorm development will be maintained and perhaps increase further as the mid-level forcing spreads into the Interstate 80 corridor of western Iowa through 21-22Z. ..Kerr/Thompson.. 08/15/2024 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...DMX...FSD...OAX...GID... LAT...LON 41959723 42419687 42259409 41119401 40999577 41179679 41389756 41959723 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 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