Severe Storms

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0146 PM CDT Wed Aug 21 2019 Valid 221200Z - 231200Z Minor adjustments were made to ongoing elevated lines based on 12Z high resolution forecast guidance. However, no significant changes were made. See previous discussion below. ..Bentley.. 08/21/2019 .PREV DISCUSSION... /ISSUED 0143 AM CDT Wed Aug 21 2019/ ...Synopsis... An upper-level shortwave trough will continue to move east-northeast across the northern Intermountain West tomorrow. An associated surface cold front will continue to move south and east into the Great Basin and through much of the northern Rockies and northern California. With a pre-frontal surface pressure trough running parallel and ahead of the cold front, the surface pressure gradient will strengthen across the Intermountain West along and ahead of the cold front. Elevated conditions are expected from northern Arizona/southern Nevada stretching northeastward into central Wyoming along/ahead of the surface cold front. Southwest-westerly sustained surface winds of 15-20 mph and RH values of 8-20% are likely to develop during tomorrow afternoon and evening across this area. High clouds may drift into northern Arizona, which could limit the southern extent of the current elevated area. Elevated conditions are also likely to develop across central/eastern portions of the Snake River Plain and vicinity tomorrow afternoon. The cold front will have passed through the area, but daytime heating should warm temperatures and mix the boundary layer enough to result in west-southwest winds of 15-25 mph and RH values of 15-20%. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0146 PM CDT Wed Aug 21 2019 Valid 221200Z - 231200Z Minor adjustments were made to ongoing elevated lines based on 12Z high resolution forecast guidance. However, no significant changes were made. See previous discussion below. ..Bentley.. 08/21/2019 .PREV DISCUSSION... /ISSUED 0143 AM CDT Wed Aug 21 2019/ ...Synopsis... An upper-level shortwave trough will continue to move east-northeast across the northern Intermountain West tomorrow. An associated surface cold front will continue to move south and east into the Great Basin and through much of the northern Rockies and northern California. With a pre-frontal surface pressure trough running parallel and ahead of the cold front, the surface pressure gradient will strengthen across the Intermountain West along and ahead of the cold front. Elevated conditions are expected from northern Arizona/southern Nevada stretching northeastward into central Wyoming along/ahead of the surface cold front. Southwest-westerly sustained surface winds of 15-20 mph and RH values of 8-20% are likely to develop during tomorrow afternoon and evening across this area. High clouds may drift into northern Arizona, which could limit the southern extent of the current elevated area. Elevated conditions are also likely to develop across central/eastern portions of the Snake River Plain and vicinity tomorrow afternoon. The cold front will have passed through the area, but daytime heating should warm temperatures and mix the boundary layer enough to result in west-southwest winds of 15-25 mph and RH values of 15-20%. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

WW 0609 Status Updates
STATUS FOR WATCH 0609 HAS NOT BEEN ISSUED YET Read more

No watches are valid as of Wed Aug 21 17:31:01 UTC 2019.

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1228 PM CDT Wed Aug 21 2019 Valid 221200Z - 231200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE NORTHERN AND CENTRAL HIGH PLAINS REGION...AND FROM NEW ENGLAND SOUTHWESTWARD TO THE CENTRAL APPALACHIANS...AND THEN WESTWARD TO OKLAHOMA... ...SUMMARY... Isolated severe wind gusts are possible Thursday from Oklahoma eastward across the Ohio Valley and into parts of New England. Meanwhile, hail or wind, occasionally reaching severe levels, will also be possible over the central and northern High Plains area. ...Synopsis... Weak flow aloft is progged across the southern half of the U.S. Thursday, while a part of troughs will cross Canada and the adjacent northern U.S. through the period. The more western of these features is expected to cross the northern Intermountain region, as an accompanying surface cold front crosses Montana/Wyoming during the afternoon and evening. Farther east, a trough crossing the Great Lakes region will also be accompanying by a cold front, that is forecast to shift eastward across the Northeast, while sagging more slowly southward across the Ohio and mid Mississippi Valleys and into Oklahoma. Both of the troughs, and the associated surface systems, will contribute to convective activity, and accompanying, low-probability severe potential, through the period. ...Parts of New England southwest across the Ohio Valley area to Oklahoma... Modest destabilization is forecast near and ahead of a surface cold front progged to stretch from New England southwestward across the Ohio Valley to Oklahoma during the afternoon, as the parent upper trough slowly advances across eastern Canada and the Great Lakes region. Scattered to isolated afternoon storm development is expected near the boundary, and southward across the warm sector. While any warm-sector storm could produce briefly/locally gusty winds, weak flow will substantially limit storm organization/longevity. Farther north however, nearer the front, an enhanced belt of cyclonic westerlies surrounding the upper trough will be sufficient to support longer-lived storms, and possibly a few quick-moving clusters of cells. As such, local risk for damaging wind gusts appears sufficient across a broad region within the the frontal zone to warrant continuation of 5% wind/MRGL risk. The risk are is being expanded northeastward across the mid Atlantic region and into parts of New England, where lesser CAPE, but stronger flow aloft, is expected. ...Portions of the northern and central high Plains... Afternoon heating will result in moderate destabilization across the high Plains near the combination lee trough/remnant cold front, with lesser destabilization to occur westward into central Montana ahead of the next/advancing cold front. Both of these fronts/troughs should focus afternoon/evening convective activity, with some clustering of convection possible over the high Plains that may locally progress eastward into lower-elevation areas. While mid-level westerly flow will remain modest across much of the area -- particularly the central high Plains, low-level southeasterlies east of the lee trough/remnant front will help to enhance the available shear, and thus a few stronger storms/storm clusters -- capable of locally gusty winds and/or hail -- are expected to evolve. Risk will primarily exist during the late afternoon and evening hours, diminishing overnight as the boundary layer stabilizes. ...MAXIMUM RISK BY HAZARD... Tornado: 2% - Marginal Wind: 5% - Marginal Hail: 5% - Marginal ..Goss.. 08/21/2019 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1228 PM CDT Wed Aug 21 2019 Valid 221200Z - 231200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE NORTHERN AND CENTRAL HIGH PLAINS REGION...AND FROM NEW ENGLAND SOUTHWESTWARD TO THE CENTRAL APPALACHIANS...AND THEN WESTWARD TO OKLAHOMA... ...SUMMARY... Isolated severe wind gusts are possible Thursday from Oklahoma eastward across the Ohio Valley and into parts of New England. Meanwhile, hail or wind, occasionally reaching severe levels, will also be possible over the central and northern High Plains area. ...Synopsis... Weak flow aloft is progged across the southern half of the U.S. Thursday, while a part of troughs will cross Canada and the adjacent northern U.S. through the period. The more western of these features is expected to cross the northern Intermountain region, as an accompanying surface cold front crosses Montana/Wyoming during the afternoon and evening. Farther east, a trough crossing the Great Lakes region will also be accompanying by a cold front, that is forecast to shift eastward across the Northeast, while sagging more slowly southward across the Ohio and mid Mississippi Valleys and into Oklahoma. Both of the troughs, and the associated surface systems, will contribute to convective activity, and accompanying, low-probability severe potential, through the period. ...Parts of New England southwest across the Ohio Valley area to Oklahoma... Modest destabilization is forecast near and ahead of a surface cold front progged to stretch from New England southwestward across the Ohio Valley to Oklahoma during the afternoon, as the parent upper trough slowly advances across eastern Canada and the Great Lakes region. Scattered to isolated afternoon storm development is expected near the boundary, and southward across the warm sector. While any warm-sector storm could produce briefly/locally gusty winds, weak flow will substantially limit storm organization/longevity. Farther north however, nearer the front, an enhanced belt of cyclonic westerlies surrounding the upper trough will be sufficient to support longer-lived storms, and possibly a few quick-moving clusters of cells. As such, local risk for damaging wind gusts appears sufficient across a broad region within the the frontal zone to warrant continuation of 5% wind/MRGL risk. The risk are is being expanded northeastward across the mid Atlantic region and into parts of New England, where lesser CAPE, but stronger flow aloft, is expected. ...Portions of the northern and central high Plains... Afternoon heating will result in moderate destabilization across the high Plains near the combination lee trough/remnant cold front, with lesser destabilization to occur westward into central Montana ahead of the next/advancing cold front. Both of these fronts/troughs should focus afternoon/evening convective activity, with some clustering of convection possible over the high Plains that may locally progress eastward into lower-elevation areas. While mid-level westerly flow will remain modest across much of the area -- particularly the central high Plains, low-level southeasterlies east of the lee trough/remnant front will help to enhance the available shear, and thus a few stronger storms/storm clusters -- capable of locally gusty winds and/or hail -- are expected to evolve. Risk will primarily exist during the late afternoon and evening hours, diminishing overnight as the boundary layer stabilizes. ...MAXIMUM RISK BY HAZARD... Tornado: 2% - Marginal Wind: 5% - Marginal Hail: 5% - Marginal ..Goss.. 08/21/2019 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1228 PM CDT Wed Aug 21 2019 Valid 221200Z - 231200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE NORTHERN AND CENTRAL HIGH PLAINS REGION...AND FROM NEW ENGLAND SOUTHWESTWARD TO THE CENTRAL APPALACHIANS...AND THEN WESTWARD TO OKLAHOMA... ...SUMMARY... Isolated severe wind gusts are possible Thursday from Oklahoma eastward across the Ohio Valley and into parts of New England. Meanwhile, hail or wind, occasionally reaching severe levels, will also be possible over the central and northern High Plains area. ...Synopsis... Weak flow aloft is progged across the southern half of the U.S. Thursday, while a part of troughs will cross Canada and the adjacent northern U.S. through the period. The more western of these features is expected to cross the northern Intermountain region, as an accompanying surface cold front crosses Montana/Wyoming during the afternoon and evening. Farther east, a trough crossing the Great Lakes region will also be accompanying by a cold front, that is forecast to shift eastward across the Northeast, while sagging more slowly southward across the Ohio and mid Mississippi Valleys and into Oklahoma. Both of the troughs, and the associated surface systems, will contribute to convective activity, and accompanying, low-probability severe potential, through the period. ...Parts of New England southwest across the Ohio Valley area to Oklahoma... Modest destabilization is forecast near and ahead of a surface cold front progged to stretch from New England southwestward across the Ohio Valley to Oklahoma during the afternoon, as the parent upper trough slowly advances across eastern Canada and the Great Lakes region. Scattered to isolated afternoon storm development is expected near the boundary, and southward across the warm sector. While any warm-sector storm could produce briefly/locally gusty winds, weak flow will substantially limit storm organization/longevity. Farther north however, nearer the front, an enhanced belt of cyclonic westerlies surrounding the upper trough will be sufficient to support longer-lived storms, and possibly a few quick-moving clusters of cells. As such, local risk for damaging wind gusts appears sufficient across a broad region within the the frontal zone to warrant continuation of 5% wind/MRGL risk. The risk are is being expanded northeastward across the mid Atlantic region and into parts of New England, where lesser CAPE, but stronger flow aloft, is expected. ...Portions of the northern and central high Plains... Afternoon heating will result in moderate destabilization across the high Plains near the combination lee trough/remnant cold front, with lesser destabilization to occur westward into central Montana ahead of the next/advancing cold front. Both of these fronts/troughs should focus afternoon/evening convective activity, with some clustering of convection possible over the high Plains that may locally progress eastward into lower-elevation areas. While mid-level westerly flow will remain modest across much of the area -- particularly the central high Plains, low-level southeasterlies east of the lee trough/remnant front will help to enhance the available shear, and thus a few stronger storms/storm clusters -- capable of locally gusty winds and/or hail -- are expected to evolve. Risk will primarily exist during the late afternoon and evening hours, diminishing overnight as the boundary layer stabilizes. ...MAXIMUM RISK BY HAZARD... Tornado: 2% - Marginal Wind: 5% - Marginal Hail: 5% - Marginal ..Goss.. 08/21/2019 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1228 PM CDT Wed Aug 21 2019 Valid 221200Z - 231200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE NORTHERN AND CENTRAL HIGH PLAINS REGION...AND FROM NEW ENGLAND SOUTHWESTWARD TO THE CENTRAL APPALACHIANS...AND THEN WESTWARD TO OKLAHOMA... ...SUMMARY... Isolated severe wind gusts are possible Thursday from Oklahoma eastward across the Ohio Valley and into parts of New England. Meanwhile, hail or wind, occasionally reaching severe levels, will also be possible over the central and northern High Plains area. ...Synopsis... Weak flow aloft is progged across the southern half of the U.S. Thursday, while a part of troughs will cross Canada and the adjacent northern U.S. through the period. The more western of these features is expected to cross the northern Intermountain region, as an accompanying surface cold front crosses Montana/Wyoming during the afternoon and evening. Farther east, a trough crossing the Great Lakes region will also be accompanying by a cold front, that is forecast to shift eastward across the Northeast, while sagging more slowly southward across the Ohio and mid Mississippi Valleys and into Oklahoma. Both of the troughs, and the associated surface systems, will contribute to convective activity, and accompanying, low-probability severe potential, through the period. ...Parts of New England southwest across the Ohio Valley area to Oklahoma... Modest destabilization is forecast near and ahead of a surface cold front progged to stretch from New England southwestward across the Ohio Valley to Oklahoma during the afternoon, as the parent upper trough slowly advances across eastern Canada and the Great Lakes region. Scattered to isolated afternoon storm development is expected near the boundary, and southward across the warm sector. While any warm-sector storm could produce briefly/locally gusty winds, weak flow will substantially limit storm organization/longevity. Farther north however, nearer the front, an enhanced belt of cyclonic westerlies surrounding the upper trough will be sufficient to support longer-lived storms, and possibly a few quick-moving clusters of cells. As such, local risk for damaging wind gusts appears sufficient across a broad region within the the frontal zone to warrant continuation of 5% wind/MRGL risk. The risk are is being expanded northeastward across the mid Atlantic region and into parts of New England, where lesser CAPE, but stronger flow aloft, is expected. ...Portions of the northern and central high Plains... Afternoon heating will result in moderate destabilization across the high Plains near the combination lee trough/remnant cold front, with lesser destabilization to occur westward into central Montana ahead of the next/advancing cold front. Both of these fronts/troughs should focus afternoon/evening convective activity, with some clustering of convection possible over the high Plains that may locally progress eastward into lower-elevation areas. While mid-level westerly flow will remain modest across much of the area -- particularly the central high Plains, low-level southeasterlies east of the lee trough/remnant front will help to enhance the available shear, and thus a few stronger storms/storm clusters -- capable of locally gusty winds and/or hail -- are expected to evolve. Risk will primarily exist during the late afternoon and evening hours, diminishing overnight as the boundary layer stabilizes. ...MAXIMUM RISK BY HAZARD... Tornado: 2% - Marginal Wind: 5% - Marginal Hail: 5% - Marginal ..Goss.. 08/21/2019 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1228 PM CDT Wed Aug 21 2019 Valid 221200Z - 231200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE NORTHERN AND CENTRAL HIGH PLAINS REGION...AND FROM NEW ENGLAND SOUTHWESTWARD TO THE CENTRAL APPALACHIANS...AND THEN WESTWARD TO OKLAHOMA... ...SUMMARY... Isolated severe wind gusts are possible Thursday from Oklahoma eastward across the Ohio Valley and into parts of New England. Meanwhile, hail or wind, occasionally reaching severe levels, will also be possible over the central and northern High Plains area. ...Synopsis... Weak flow aloft is progged across the southern half of the U.S. Thursday, while a part of troughs will cross Canada and the adjacent northern U.S. through the period. The more western of these features is expected to cross the northern Intermountain region, as an accompanying surface cold front crosses Montana/Wyoming during the afternoon and evening. Farther east, a trough crossing the Great Lakes region will also be accompanying by a cold front, that is forecast to shift eastward across the Northeast, while sagging more slowly southward across the Ohio and mid Mississippi Valleys and into Oklahoma. Both of the troughs, and the associated surface systems, will contribute to convective activity, and accompanying, low-probability severe potential, through the period. ...Parts of New England southwest across the Ohio Valley area to Oklahoma... Modest destabilization is forecast near and ahead of a surface cold front progged to stretch from New England southwestward across the Ohio Valley to Oklahoma during the afternoon, as the parent upper trough slowly advances across eastern Canada and the Great Lakes region. Scattered to isolated afternoon storm development is expected near the boundary, and southward across the warm sector. While any warm-sector storm could produce briefly/locally gusty winds, weak flow will substantially limit storm organization/longevity. Farther north however, nearer the front, an enhanced belt of cyclonic westerlies surrounding the upper trough will be sufficient to support longer-lived storms, and possibly a few quick-moving clusters of cells. As such, local risk for damaging wind gusts appears sufficient across a broad region within the the frontal zone to warrant continuation of 5% wind/MRGL risk. The risk are is being expanded northeastward across the mid Atlantic region and into parts of New England, where lesser CAPE, but stronger flow aloft, is expected. ...Portions of the northern and central high Plains... Afternoon heating will result in moderate destabilization across the high Plains near the combination lee trough/remnant cold front, with lesser destabilization to occur westward into central Montana ahead of the next/advancing cold front. Both of these fronts/troughs should focus afternoon/evening convective activity, with some clustering of convection possible over the high Plains that may locally progress eastward into lower-elevation areas. While mid-level westerly flow will remain modest across much of the area -- particularly the central high Plains, low-level southeasterlies east of the lee trough/remnant front will help to enhance the available shear, and thus a few stronger storms/storm clusters -- capable of locally gusty winds and/or hail -- are expected to evolve. Risk will primarily exist during the late afternoon and evening hours, diminishing overnight as the boundary layer stabilizes. ...MAXIMUM RISK BY HAZARD... Tornado: 2% - Marginal Wind: 5% - Marginal Hail: 5% - Marginal ..Goss.. 08/21/2019 Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1153 AM CDT Wed Aug 21 2019 Valid 211700Z - 221200Z ...NO CRITICAL AREAS... Sundowner winds are possible across Santa Barbara county in southern California this evening and may lead to isolated elevated fire weather conditions, but the isolated and short duration of the threat precludes inclusion of an elevated delineation. No changes have been made to the previous outlook. See previous discussion below. ..Bentley.. 08/21/2019 .PREV DISCUSSION... /ISSUED 0136 AM CDT Wed Aug 21 2019/ ...Synopsis... An upper-level shortwave trough will move into the Pacific Northwest and northern Rockies today with an associated surface cold front sweeping east and south through the Pacific Northwest. Hot/dry/unstable conditions are expected to continue across much of the Intermountain West ahead of the cold front and north/west of the subtropical moisture in the Southwest and Rocky Mountains. Elevated conditions may develop just ahead of the cold front across eastern Washington/Oregon, but conditions should be short-lived and followed by cooler, moist air. Isolated thunderstorms are possible along the cold front across portions of the inland Pacific Northwest. Additionally, isolated dry thunderstorms may form across portions of the northern Rockies. However, the forecast airmass change and marginal fuel conditions where storms may develop preclude an isolated dry thunderstorm area. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1153 AM CDT Wed Aug 21 2019 Valid 211700Z - 221200Z ...NO CRITICAL AREAS... Sundowner winds are possible across Santa Barbara county in southern California this evening and may lead to isolated elevated fire weather conditions, but the isolated and short duration of the threat precludes inclusion of an elevated delineation. No changes have been made to the previous outlook. See previous discussion below. ..Bentley.. 08/21/2019 .PREV DISCUSSION... /ISSUED 0136 AM CDT Wed Aug 21 2019/ ...Synopsis... An upper-level shortwave trough will move into the Pacific Northwest and northern Rockies today with an associated surface cold front sweeping east and south through the Pacific Northwest. Hot/dry/unstable conditions are expected to continue across much of the Intermountain West ahead of the cold front and north/west of the subtropical moisture in the Southwest and Rocky Mountains. Elevated conditions may develop just ahead of the cold front across eastern Washington/Oregon, but conditions should be short-lived and followed by cooler, moist air. Isolated thunderstorms are possible along the cold front across portions of the inland Pacific Northwest. Additionally, isolated dry thunderstorms may form across portions of the northern Rockies. However, the forecast airmass change and marginal fuel conditions where storms may develop preclude an isolated dry thunderstorm area. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1153 AM CDT Wed Aug 21 2019 Valid 211700Z - 221200Z ...NO CRITICAL AREAS... Sundowner winds are possible across Santa Barbara county in southern California this evening and may lead to isolated elevated fire weather conditions, but the isolated and short duration of the threat precludes inclusion of an elevated delineation. No changes have been made to the previous outlook. See previous discussion below. ..Bentley.. 08/21/2019 .PREV DISCUSSION... /ISSUED 0136 AM CDT Wed Aug 21 2019/ ...Synopsis... An upper-level shortwave trough will move into the Pacific Northwest and northern Rockies today with an associated surface cold front sweeping east and south through the Pacific Northwest. Hot/dry/unstable conditions are expected to continue across much of the Intermountain West ahead of the cold front and north/west of the subtropical moisture in the Southwest and Rocky Mountains. Elevated conditions may develop just ahead of the cold front across eastern Washington/Oregon, but conditions should be short-lived and followed by cooler, moist air. Isolated thunderstorms are possible along the cold front across portions of the inland Pacific Northwest. Additionally, isolated dry thunderstorms may form across portions of the northern Rockies. However, the forecast airmass change and marginal fuel conditions where storms may develop preclude an isolated dry thunderstorm area. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1153 AM CDT Wed Aug 21 2019 Valid 211700Z - 221200Z ...NO CRITICAL AREAS... Sundowner winds are possible across Santa Barbara county in southern California this evening and may lead to isolated elevated fire weather conditions, but the isolated and short duration of the threat precludes inclusion of an elevated delineation. No changes have been made to the previous outlook. See previous discussion below. ..Bentley.. 08/21/2019 .PREV DISCUSSION... /ISSUED 0136 AM CDT Wed Aug 21 2019/ ...Synopsis... An upper-level shortwave trough will move into the Pacific Northwest and northern Rockies today with an associated surface cold front sweeping east and south through the Pacific Northwest. Hot/dry/unstable conditions are expected to continue across much of the Intermountain West ahead of the cold front and north/west of the subtropical moisture in the Southwest and Rocky Mountains. Elevated conditions may develop just ahead of the cold front across eastern Washington/Oregon, but conditions should be short-lived and followed by cooler, moist air. Isolated thunderstorms are possible along the cold front across portions of the inland Pacific Northwest. Additionally, isolated dry thunderstorms may form across portions of the northern Rockies. However, the forecast airmass change and marginal fuel conditions where storms may develop preclude an isolated dry thunderstorm area. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1132 AM CDT Wed Aug 21 2019 Valid 211630Z - 221200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE NORTHEAST/MID-ATLANTIC STATES... ...SUMMARY... Severe thunderstorms are expected this afternoon and evening across parts of the Northeast/Mid-Atlantic States, with other severe storms possible across the central Great Plains. ...Northeast/Mid-Atlantic States... A shortwave trough will continue to progress east-northeastward from eastern New York toward northern New England, while a warm front slowly spreads northward across southern New England. With broken cloud cover lingering in most areas, modest overall destabilization is expected along/south of the warm front where low-level/deep-layer shear will be maximized. The environment will support the possibility of supercells/bowing segments particularly across southeast New York and southern New England, with severe hail/wind possible along with some tornado risk. Multicells with damaging winds are possible farther south within the warm sector. For additional short-term details, see Mesoscale Discussion 1825. ...Kansas/Missouri/far southeast Nebraska to Missouri/Illinois... The remnants of overnight convection continue to decay across the region with cloud cover/outflow influencing an effective boundary across southern portions of Kansas/Missouri. Surface-based thunderstorms should develop/intensify later this afternoon particularly across southern/eastern Kansas into western Missouri within a moist/unstable environment. Relatively weak tropospheric winds may limit overall storm organization, but the strongest storms will pose a damaging wind/severe hail risk. ...Wyoming/Colorado Front Range to central High Plains... Isolated to widely scattered thunderstorms should develop this afternoon over the eastern mountains and foothills from northern Wyoming across central/southern Colorado, offering the potential for isolated severe hail and gusts. Activity is expected predominantly in the post-frontal/upslope region where lift is maximized by a combination of upslope flow and diabatic surface heating of the higher terrain (minimizing MLCINH). Mid-level flow is forecast to be modest; however, vertical shear will be stronger than over lower elevations ahead of the front because of the backed boundary-layer winds and relatively extended low-level hodographs. As such, a mixture of supercellular and multicellular structures are possible. ..Guyer/Coniglio.. 08/21/2019 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1132 AM CDT Wed Aug 21 2019 Valid 211630Z - 221200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE NORTHEAST/MID-ATLANTIC STATES... ...SUMMARY... Severe thunderstorms are expected this afternoon and evening across parts of the Northeast/Mid-Atlantic States, with other severe storms possible across the central Great Plains. ...Northeast/Mid-Atlantic States... A shortwave trough will continue to progress east-northeastward from eastern New York toward northern New England, while a warm front slowly spreads northward across southern New England. With broken cloud cover lingering in most areas, modest overall destabilization is expected along/south of the warm front where low-level/deep-layer shear will be maximized. The environment will support the possibility of supercells/bowing segments particularly across southeast New York and southern New England, with severe hail/wind possible along with some tornado risk. Multicells with damaging winds are possible farther south within the warm sector. For additional short-term details, see Mesoscale Discussion 1825. ...Kansas/Missouri/far southeast Nebraska to Missouri/Illinois... The remnants of overnight convection continue to decay across the region with cloud cover/outflow influencing an effective boundary across southern portions of Kansas/Missouri. Surface-based thunderstorms should develop/intensify later this afternoon particularly across southern/eastern Kansas into western Missouri within a moist/unstable environment. Relatively weak tropospheric winds may limit overall storm organization, but the strongest storms will pose a damaging wind/severe hail risk. ...Wyoming/Colorado Front Range to central High Plains... Isolated to widely scattered thunderstorms should develop this afternoon over the eastern mountains and foothills from northern Wyoming across central/southern Colorado, offering the potential for isolated severe hail and gusts. Activity is expected predominantly in the post-frontal/upslope region where lift is maximized by a combination of upslope flow and diabatic surface heating of the higher terrain (minimizing MLCINH). Mid-level flow is forecast to be modest; however, vertical shear will be stronger than over lower elevations ahead of the front because of the backed boundary-layer winds and relatively extended low-level hodographs. As such, a mixture of supercellular and multicellular structures are possible. ..Guyer/Coniglio.. 08/21/2019 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1132 AM CDT Wed Aug 21 2019 Valid 211630Z - 221200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE NORTHEAST/MID-ATLANTIC STATES... ...SUMMARY... Severe thunderstorms are expected this afternoon and evening across parts of the Northeast/Mid-Atlantic States, with other severe storms possible across the central Great Plains. ...Northeast/Mid-Atlantic States... A shortwave trough will continue to progress east-northeastward from eastern New York toward northern New England, while a warm front slowly spreads northward across southern New England. With broken cloud cover lingering in most areas, modest overall destabilization is expected along/south of the warm front where low-level/deep-layer shear will be maximized. The environment will support the possibility of supercells/bowing segments particularly across southeast New York and southern New England, with severe hail/wind possible along with some tornado risk. Multicells with damaging winds are possible farther south within the warm sector. For additional short-term details, see Mesoscale Discussion 1825. ...Kansas/Missouri/far southeast Nebraska to Missouri/Illinois... The remnants of overnight convection continue to decay across the region with cloud cover/outflow influencing an effective boundary across southern portions of Kansas/Missouri. Surface-based thunderstorms should develop/intensify later this afternoon particularly across southern/eastern Kansas into western Missouri within a moist/unstable environment. Relatively weak tropospheric winds may limit overall storm organization, but the strongest storms will pose a damaging wind/severe hail risk. ...Wyoming/Colorado Front Range to central High Plains... Isolated to widely scattered thunderstorms should develop this afternoon over the eastern mountains and foothills from northern Wyoming across central/southern Colorado, offering the potential for isolated severe hail and gusts. Activity is expected predominantly in the post-frontal/upslope region where lift is maximized by a combination of upslope flow and diabatic surface heating of the higher terrain (minimizing MLCINH). Mid-level flow is forecast to be modest; however, vertical shear will be stronger than over lower elevations ahead of the front because of the backed boundary-layer winds and relatively extended low-level hodographs. As such, a mixture of supercellular and multicellular structures are possible. ..Guyer/Coniglio.. 08/21/2019 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1132 AM CDT Wed Aug 21 2019 Valid 211630Z - 221200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE NORTHEAST/MID-ATLANTIC STATES... ...SUMMARY... Severe thunderstorms are expected this afternoon and evening across parts of the Northeast/Mid-Atlantic States, with other severe storms possible across the central Great Plains. ...Northeast/Mid-Atlantic States... A shortwave trough will continue to progress east-northeastward from eastern New York toward northern New England, while a warm front slowly spreads northward across southern New England. With broken cloud cover lingering in most areas, modest overall destabilization is expected along/south of the warm front where low-level/deep-layer shear will be maximized. The environment will support the possibility of supercells/bowing segments particularly across southeast New York and southern New England, with severe hail/wind possible along with some tornado risk. Multicells with damaging winds are possible farther south within the warm sector. For additional short-term details, see Mesoscale Discussion 1825. ...Kansas/Missouri/far southeast Nebraska to Missouri/Illinois... The remnants of overnight convection continue to decay across the region with cloud cover/outflow influencing an effective boundary across southern portions of Kansas/Missouri. Surface-based thunderstorms should develop/intensify later this afternoon particularly across southern/eastern Kansas into western Missouri within a moist/unstable environment. Relatively weak tropospheric winds may limit overall storm organization, but the strongest storms will pose a damaging wind/severe hail risk. ...Wyoming/Colorado Front Range to central High Plains... Isolated to widely scattered thunderstorms should develop this afternoon over the eastern mountains and foothills from northern Wyoming across central/southern Colorado, offering the potential for isolated severe hail and gusts. Activity is expected predominantly in the post-frontal/upslope region where lift is maximized by a combination of upslope flow and diabatic surface heating of the higher terrain (minimizing MLCINH). Mid-level flow is forecast to be modest; however, vertical shear will be stronger than over lower elevations ahead of the front because of the backed boundary-layer winds and relatively extended low-level hodographs. As such, a mixture of supercellular and multicellular structures are possible. ..Guyer/Coniglio.. 08/21/2019 Read more

MD 1825 CONCERNING SEVERE POTENTIAL...WATCH POSSIBLE FOR NORTHERN MID ATLANTIC COAST REGION THROUGH SOUTHERN NEW ENGLAND
Mesoscale Discussion 1825 NWS Storm Prediction Center Norman OK 1031 AM CDT Wed Aug 21 2019 Areas affected...Northern Mid Atlantic Coast region through southern New England Concerning...Severe potential...Watch possible Valid 211531Z - 211730Z Probability of Watch Issuance...60 percent SUMMARY...Intensifying thunderstorms posing a risk for potentially damaging wind gusts and, perhaps, an isolated tornado or two, appear increasingly possible by 2-4 PM EDT. This could require the issuance of one or two severe weather watches. DISCUSSION...Convective development appears to be undergoing at least some gradual intensification, within a narrow band now overspreading the Champlain and Hudson Valleys, and as far south as northern New Jersey. This appears to be occurring on the leading edge of mid-level forcing for ascent associated with a remnant convectively generated or enhanced perturbation, which is forecast to progress into and through western and northern New England by mid to late afternoon. This may be trailed to the southwest by another area of mid-level forcing for ascent spreading northeastward across the northern Mid Atlantic Coast region into southern New England. Based on latest observational data, seasonably moist boundary layer air may mostly remain confined to the south of a weak surface front, reinforced by rain-cooled air associated with weakening convection preceding the main ongoing band. This extends roughly from the leading edge of the convective band across northern Massachusetts, though this boundary could shift northward some into and through the afternoon. To the south of the front, insolation during the next few hours is expected to contribute to moderate mixed-layer CAPE of 1000-2000 J/kg, coincident with strengthening of west-southwesterly flow in the 700-500 mb layer. This may contribute to an environment increasingly conducive to organized convection by 18-20Z, which could include further intensification of the ongoing line and perhaps additional discrete storms, with supercell structures possible. Although low-level hodographs may be somewhat modest in size, a tornado or two might not be out of the question, mainly near the surface boundary across southern New England. Otherwise, strongest storms probably will pose a risk for potentially damaging wind gusts. ..Kerr/Guyer.. 08/21/2019 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...GYX...BOX...BTV...OKX...ALY...PHI...BGM...CTP... LWX... LAT...LON 43597276 43207186 43187060 42567029 41777017 40667291 39807417 39187526 39897661 40957572 41367524 41547425 41877353 42307324 43597276 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0759 AM CDT Wed Aug 21 2019 Valid 211300Z - 221200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PARTS OF THE NORTHEAST... ...SUMMARY... The severe-thunderstorm threat appears most concentrated today over portions of the Northeast. ...Synopsis... In mid/upper levels, a relatively low-amplitude pattern will persist across most of the CONUS, with the main belt of westerlies covering about the northern 1/3 from the Pacific Northwest to New England. A synoptic-scale cyclone -- initially over northeastern ON and adjoining Hudson Bay waters -- will pivot slowly southeastward and eastward to nearby parts of QC through the period. An attendant positively tilted trough will move southeastward then eastward over the upper Great Lakes, followed by another, somewhat stronger trough across northern MN and Lake Superior late tonight. Downstream, a shortwave trough was evident in moisture-channel imagery across Lake Ontario, western NY, and the upper Ohio Valley. This feature will move eastward across the Mid-Atlantic region and New England through 03Z. In weaker westerlies aloft, MCVs and related vorticity lobes from prior overnight convection in the central Plains will move eastward over parts of the lower Missouri and mid Mississippi Valley regions today into this evening. At the surface, the 11Z analysis depicted a cold front from Lake Huron to central Lake Michigan, south-central IA, southeastern NE, northwestern KS, and portions of east-central/southeastern CO. By 00Z, this front should reach southeastern ON, southern Lower MI, north-central MO, central KS, to near the eastern CO/NM line. By 12Z the front should extend from northern NY to southwestern OH, southern IL, north-central/northeastern OK, the TX Panhandle, and northeastern NM. Over the central/southern Plains and mid Mississippi Valley, the front will be preceded by several convective outflow boundaries of variable baroclinicity. A warm front -- initially drawn near the southern New England coast and across southeastern NY/northeastern PA area -- will shift northeastward across much of the remainder of eastern NY and New England through the period. ...Northeast... Large-scale DCVA/ascent and warm advection, each preceding the aforementioned mid/upper-level shortwave trough, will spread over a favorably moist and destabilizing warm sector today in support of multiple rounds of convection, with sporadic damaging to severe gusts. Severe hail also is possible from the most intense/deepest cells, especially across portions of eastern NY and New England where the buoyancy/shear parameter space will best support organized multicells and isolated supercells within the convective regime. In addition to the influences aloft, low-level destabilization will occur as the warm-frontal zone moves northeastward, moisture advection occurs, and pockets of persistent diurnal heating occur around and between areas of antecedent cloud cover. These processes should result in preconvective MLCAPE commonly in the 1000-1500 J/KG range. In the absence of an EML or other mechanisms to support strong capping, MLCINH will weaken rapidly through the morning into midday, rendering a situation where only subtle boundary-layer forcing (e.g., surface heating, weak low-level convergence zones, outflow/differential-heating boundaries) will be needed to generate deep convection. In general, vertical shear should strengthen and instability will weaken with northward extent, though a broad area of overlap favorable for severe defines the 15%/slight-risk area. With somewhat backed low-level winds in the warm-frontal zone, and a southerly component just to its south in the warm sector, hodographs also may enlarge enough to yield isolated mesocyclones and a marginal tornado threat, generally overlapping the greatest hail potential, mainly over portions of New England. ...Central High Plains and Rockies/Foothills... Isolated to widely scattered thunderstorms should develop this afternoon over the eastern mountains and foothills from northern WY across central/southern CO, offering the potential for isolated severe hail and gusts. Activity is expected predominantly in the post-frontal/upslope region where lift is maximized by a combination of upslope flow and diabatic surface heating of the higher terrain (minimizing MLCINH). Midlevel flow is forecast to be modest; however, vertical shear will be stronger than over lower elevations ahead of the front because of the backed boundary-layer winds and relatively extended low-level hodographs. As such, a mixture of supercellular and multicellular structures are possible. ...KS/MO/IL... Isolated to numerous thunderstorms are possible this afternoon and evening along and ahead of the front, some of which may produce severe gusts and hail. Large areas of antecedent cloud cover and precip will disperse, but in doing so, will delay diurnal destabilization across much of KS/MO. Outflow and differential- heating boundaries left behind by this activity, and their intersection(s) with the frontal zone, should be primary foci for convective development and intensification this afternoon and evening. Where the boundary layer can heat well, and is relatively undisturbed by prior convective activity, steep lapse rates and surface dew points in the upper 60s to upper 70s F will support pockets of 3000-4000 J/kg MLCAPE, perhaps locally higher. Considerable uncertainties linger regarding the ultimate location, orientation and strength of the prefrontal boundaries. One or two relative concentrations of severe potential may develop as convection aggregates around areas of greatest diurnal destabilization and boundary-related forcing. However, mesoscale uncertainties preclude assigning any greater unconditional probabilities with the broader marginal risk, at this early juncture. Weak mid/upper-level winds, and related lack of more-robust deep shear, also will be limiting factors for a better-organized severe threat. ..Edwards/Dean.. 08/21/2019 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0759 AM CDT Wed Aug 21 2019 Valid 211300Z - 221200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PARTS OF THE NORTHEAST... ...SUMMARY... The severe-thunderstorm threat appears most concentrated today over portions of the Northeast. ...Synopsis... In mid/upper levels, a relatively low-amplitude pattern will persist across most of the CONUS, with the main belt of westerlies covering about the northern 1/3 from the Pacific Northwest to New England. A synoptic-scale cyclone -- initially over northeastern ON and adjoining Hudson Bay waters -- will pivot slowly southeastward and eastward to nearby parts of QC through the period. An attendant positively tilted trough will move southeastward then eastward over the upper Great Lakes, followed by another, somewhat stronger trough across northern MN and Lake Superior late tonight. Downstream, a shortwave trough was evident in moisture-channel imagery across Lake Ontario, western NY, and the upper Ohio Valley. This feature will move eastward across the Mid-Atlantic region and New England through 03Z. In weaker westerlies aloft, MCVs and related vorticity lobes from prior overnight convection in the central Plains will move eastward over parts of the lower Missouri and mid Mississippi Valley regions today into this evening. At the surface, the 11Z analysis depicted a cold front from Lake Huron to central Lake Michigan, south-central IA, southeastern NE, northwestern KS, and portions of east-central/southeastern CO. By 00Z, this front should reach southeastern ON, southern Lower MI, north-central MO, central KS, to near the eastern CO/NM line. By 12Z the front should extend from northern NY to southwestern OH, southern IL, north-central/northeastern OK, the TX Panhandle, and northeastern NM. Over the central/southern Plains and mid Mississippi Valley, the front will be preceded by several convective outflow boundaries of variable baroclinicity. A warm front -- initially drawn near the southern New England coast and across southeastern NY/northeastern PA area -- will shift northeastward across much of the remainder of eastern NY and New England through the period. ...Northeast... Large-scale DCVA/ascent and warm advection, each preceding the aforementioned mid/upper-level shortwave trough, will spread over a favorably moist and destabilizing warm sector today in support of multiple rounds of convection, with sporadic damaging to severe gusts. Severe hail also is possible from the most intense/deepest cells, especially across portions of eastern NY and New England where the buoyancy/shear parameter space will best support organized multicells and isolated supercells within the convective regime. In addition to the influences aloft, low-level destabilization will occur as the warm-frontal zone moves northeastward, moisture advection occurs, and pockets of persistent diurnal heating occur around and between areas of antecedent cloud cover. These processes should result in preconvective MLCAPE commonly in the 1000-1500 J/KG range. In the absence of an EML or other mechanisms to support strong capping, MLCINH will weaken rapidly through the morning into midday, rendering a situation where only subtle boundary-layer forcing (e.g., surface heating, weak low-level convergence zones, outflow/differential-heating boundaries) will be needed to generate deep convection. In general, vertical shear should strengthen and instability will weaken with northward extent, though a broad area of overlap favorable for severe defines the 15%/slight-risk area. With somewhat backed low-level winds in the warm-frontal zone, and a southerly component just to its south in the warm sector, hodographs also may enlarge enough to yield isolated mesocyclones and a marginal tornado threat, generally overlapping the greatest hail potential, mainly over portions of New England. ...Central High Plains and Rockies/Foothills... Isolated to widely scattered thunderstorms should develop this afternoon over the eastern mountains and foothills from northern WY across central/southern CO, offering the potential for isolated severe hail and gusts. Activity is expected predominantly in the post-frontal/upslope region where lift is maximized by a combination of upslope flow and diabatic surface heating of the higher terrain (minimizing MLCINH). Midlevel flow is forecast to be modest; however, vertical shear will be stronger than over lower elevations ahead of the front because of the backed boundary-layer winds and relatively extended low-level hodographs. As such, a mixture of supercellular and multicellular structures are possible. ...KS/MO/IL... Isolated to numerous thunderstorms are possible this afternoon and evening along and ahead of the front, some of which may produce severe gusts and hail. Large areas of antecedent cloud cover and precip will disperse, but in doing so, will delay diurnal destabilization across much of KS/MO. Outflow and differential- heating boundaries left behind by this activity, and their intersection(s) with the frontal zone, should be primary foci for convective development and intensification this afternoon and evening. Where the boundary layer can heat well, and is relatively undisturbed by prior convective activity, steep lapse rates and surface dew points in the upper 60s to upper 70s F will support pockets of 3000-4000 J/kg MLCAPE, perhaps locally higher. Considerable uncertainties linger regarding the ultimate location, orientation and strength of the prefrontal boundaries. One or two relative concentrations of severe potential may develop as convection aggregates around areas of greatest diurnal destabilization and boundary-related forcing. However, mesoscale uncertainties preclude assigning any greater unconditional probabilities with the broader marginal risk, at this early juncture. Weak mid/upper-level winds, and related lack of more-robust deep shear, also will be limiting factors for a better-organized severe threat. ..Edwards/Dean.. 08/21/2019 Read more