Severe Storms

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0457 PM CDT Mon Aug 19 2024 Valid 211200Z - 271200Z Omega blocking over the central CONUS is forecast to remain through the majority of the extended forecast period. On the western flank of the block, mid-level troughing will persist over parts of the West Coast into next weekend. Enhanced flow aloft, with several embedded shortwave troughs will support periodic dry and breezy conditions over parts of the Northwest and Great Basin. Toward the end of the week, a strong upper low will move south along the coast supporting an increase in thunderstorm potential, along with continued dry and breezy conditions over the Great Basin. Elevated to potentially critical fire-weather conditions are possible. ...Northwest and Great Basin... Moderate southwesterly flow aloft is forecast to remain in place over the western US through much of the week. With stronger flow aloft overspreading a warm and dry air mass across parts of the southern Northwest and Great Basin, dry and windy conditions are possible through midweek. Elevated to critical fire-weather conditions are possible over parts of NV, UT and into southern OR/ID through D5/Friday. Confidence in stronger sustained winds overlapping critical RH and dry fuels is somewhat limited currently, though the approach of the upper low/trough is expected to support potentially higher gusts over much of the Southwest D4/Thursday and into the weekend. Increasing monsoon moisture is also expected over parts of the Western US beginning D4/Thursday. Medium-range guidance shows a plume of 0.6 to 0.8 inch PWATs moving into the Pacific Northwest ahead of the upper low. Some dry lightning will be possible with isolated to widely scattered storms through D6/Saturday. Confidence is highest that dry thunder probabilities could be needed over parts of northern and central OR through the end of the work week. However, the exact storm coverage and overlap with the best fuels remains uncertain. ..Lyons.. 08/19/2024 ...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 0457 PM CDT Mon Aug 19 2024 Valid 211200Z - 271200Z Omega blocking over the central CONUS is forecast to remain through the majority of the extended forecast period. On the western flank of the block, mid-level troughing will persist over parts of the West Coast into next weekend. Enhanced flow aloft, with several embedded shortwave troughs will support periodic dry and breezy conditions over parts of the Northwest and Great Basin. Toward the end of the week, a strong upper low will move south along the coast supporting an increase in thunderstorm potential, along with continued dry and breezy conditions over the Great Basin. Elevated to potentially critical fire-weather conditions are possible. ...Northwest and Great Basin... Moderate southwesterly flow aloft is forecast to remain in place over the western US through much of the week. With stronger flow aloft overspreading a warm and dry air mass across parts of the southern Northwest and Great Basin, dry and windy conditions are possible through midweek. Elevated to critical fire-weather conditions are possible over parts of NV, UT and into southern OR/ID through D5/Friday. Confidence in stronger sustained winds overlapping critical RH and dry fuels is somewhat limited currently, though the approach of the upper low/trough is expected to support potentially higher gusts over much of the Southwest D4/Thursday and into the weekend. Increasing monsoon moisture is also expected over parts of the Western US beginning D4/Thursday. Medium-range guidance shows a plume of 0.6 to 0.8 inch PWATs moving into the Pacific Northwest ahead of the upper low. Some dry lightning will be possible with isolated to widely scattered storms through D6/Saturday. Confidence is highest that dry thunder probabilities could be needed over parts of northern and central OR through the end of the work week. However, the exact storm coverage and overlap with the best fuels remains uncertain. ..Lyons.. 08/19/2024 ...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 0457 PM CDT Mon Aug 19 2024 Valid 211200Z - 271200Z Omega blocking over the central CONUS is forecast to remain through the majority of the extended forecast period. On the western flank of the block, mid-level troughing will persist over parts of the West Coast into next weekend. Enhanced flow aloft, with several embedded shortwave troughs will support periodic dry and breezy conditions over parts of the Northwest and Great Basin. Toward the end of the week, a strong upper low will move south along the coast supporting an increase in thunderstorm potential, along with continued dry and breezy conditions over the Great Basin. Elevated to potentially critical fire-weather conditions are possible. ...Northwest and Great Basin... Moderate southwesterly flow aloft is forecast to remain in place over the western US through much of the week. With stronger flow aloft overspreading a warm and dry air mass across parts of the southern Northwest and Great Basin, dry and windy conditions are possible through midweek. Elevated to critical fire-weather conditions are possible over parts of NV, UT and into southern OR/ID through D5/Friday. Confidence in stronger sustained winds overlapping critical RH and dry fuels is somewhat limited currently, though the approach of the upper low/trough is expected to support potentially higher gusts over much of the Southwest D4/Thursday and into the weekend. Increasing monsoon moisture is also expected over parts of the Western US beginning D4/Thursday. Medium-range guidance shows a plume of 0.6 to 0.8 inch PWATs moving into the Pacific Northwest ahead of the upper low. Some dry lightning will be possible with isolated to widely scattered storms through D6/Saturday. Confidence is highest that dry thunder probabilities could be needed over parts of northern and central OR through the end of the work week. However, the exact storm coverage and overlap with the best fuels remains uncertain. ..Lyons.. 08/19/2024 ...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 0457 PM CDT Mon Aug 19 2024 Valid 211200Z - 271200Z Omega blocking over the central CONUS is forecast to remain through the majority of the extended forecast period. On the western flank of the block, mid-level troughing will persist over parts of the West Coast into next weekend. Enhanced flow aloft, with several embedded shortwave troughs will support periodic dry and breezy conditions over parts of the Northwest and Great Basin. Toward the end of the week, a strong upper low will move south along the coast supporting an increase in thunderstorm potential, along with continued dry and breezy conditions over the Great Basin. Elevated to potentially critical fire-weather conditions are possible. ...Northwest and Great Basin... Moderate southwesterly flow aloft is forecast to remain in place over the western US through much of the week. With stronger flow aloft overspreading a warm and dry air mass across parts of the southern Northwest and Great Basin, dry and windy conditions are possible through midweek. Elevated to critical fire-weather conditions are possible over parts of NV, UT and into southern OR/ID through D5/Friday. Confidence in stronger sustained winds overlapping critical RH and dry fuels is somewhat limited currently, though the approach of the upper low/trough is expected to support potentially higher gusts over much of the Southwest D4/Thursday and into the weekend. Increasing monsoon moisture is also expected over parts of the Western US beginning D4/Thursday. Medium-range guidance shows a plume of 0.6 to 0.8 inch PWATs moving into the Pacific Northwest ahead of the upper low. Some dry lightning will be possible with isolated to widely scattered storms through D6/Saturday. Confidence is highest that dry thunder probabilities could be needed over parts of northern and central OR through the end of the work week. However, the exact storm coverage and overlap with the best fuels remains uncertain. ..Lyons.. 08/19/2024 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

MD 1959 CONCERNING SEVERE POTENTIAL...WATCH POSSIBLE FOR MUCH OF WESTERN MONTANA AND THE CENTRAL IDAHO MOUNTAINS
Mesoscale Discussion 1959 NWS Storm Prediction Center Norman OK 0321 PM CDT Mon Aug 19 2024 Areas affected...much of western Montana and the central Idaho Mountains Concerning...Severe potential...Watch possible Valid 192021Z - 192145Z Probability of Watch Issuance...60 percent SUMMARY...High-based thunderstorms are likely this afternoon and evening with a threat for severe wind gusts. DISCUSSION...Temperatures have warmed into the mid 80s across the central Idaho mountains which has eroded inhibition and resulted in scattered thunderstorm development. RAP forecast soundings show very deep mixing (perhaps as deep as 5-6km) which will support evaporative cooling and strengthening downbursts. The downstream environment across western Montana still shows moderate inhibition (per SPC mesoanalysis) which should erode further as warming continues. As this occurs, expect strengthening of ongoing storms and additional development across western Montana. Moderate upper-level flow ahead of the Pacific Northwest upper-level trough will overspread this region late this afternoon and evening which may result in storm organization and a greater severe weather threat. A severe thunderstorm watch may be needed. ..Bentley/Hart.. 08/19/2024 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...TFX...PIH...MSO...BOI...OTX... LAT...LON 44431433 44981525 47541489 49021400 49041176 49030985 48580993 46571090 45291195 44541301 44371348 44431433 Read more

MD 1957 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR VIRGINIA AND PORTIONS OF NORTH CAROLINA
Mesoscale Discussion 1957 NWS Storm Prediction Center Norman OK 0224 PM CDT Mon Aug 19 2024 Areas affected...Virginia and portions of North Carolina Concerning...Severe potential...Watch unlikely Valid 191924Z - 192130Z Probability of Watch Issuance...20 percent SUMMARY...Scattered thunderstorm activity will have potential to produce downbursts with strong to severe gusts. DISCUSSION...Thunderstorm activity has increased in coverage across Virginia and North Carolina this afternoon as lift from a mid-level trough overspreads a cold front across the region. Breaks in morning cloud cover have allowed for sufficient daytime heating and temperatures in the mid to upper 80s, with low-level lapse rates around 8 C/km. MLCAPE around 1000-1500 J/kg is analyzed in RAP objective analysis. While deep layer shear is weak, steep lapse rates and precipitable water values above 1 inch will support potential for a few strong storms with potential for downbursts capable of strong to severe gusts. Overall, this threat will likely remain too localized for watch issuance. ..Thornton/Hart.. 08/19/2024 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...PHI...AKQ...MHX...LWX...RAH...RNK... LAT...LON 36117983 36997936 38257821 38977726 39367670 39577629 39397579 38517527 37817552 36627595 35907616 35037641 34857648 35387934 36117983 Read more

MD 1958 CONCERNING SEVERE POTENTIAL...WATCH POSSIBLE FOR EASTERN MONTANA AND WESTERN NORTH DAKOTA.
Mesoscale Discussion 1958 NWS Storm Prediction Center Norman OK 0244 PM CDT Mon Aug 19 2024 Areas affected...Eastern Montana and western North Dakota. Concerning...Severe potential...Watch possible Valid 191944Z - 192115Z Probability of Watch Issuance...40 percent SUMMARY...Some intensification is possible as storms move northeast across eastern Montana. A watch may be needed. DISCUSSION...A slow moving cluster of storms has persisted across eastern Montana through most of the day today. Somewhat more robust convection has developed southeast of the primary cluster in the presence of greater instability (2000+ J/kg MLCAPE). SPC mesoanalysis shows inhibition has mostly eroded ahead of these storms and it should completely erode in the next 1 to 2 hours. A speed max overspread eastern Montana within the last hour (sampled 40-45 knots between 4-5km on the GGW VWP). This increase in deep layer shear may support an increase in storm intensity later this afternoon. A few thunderstorms capable of large hail and severe wind gusts are expected this evening. A severe thunderstorm watch may be needed. ..Bentley/Hart.. 08/19/2024 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...BIS...UNR...BYZ...GGW... LAT...LON 45850479 45840523 46080584 46390631 46660628 47860617 48570558 48940453 48670312 47360266 46180324 45800421 45850479 Read more

WW 0640 Status Updates
STATUS FOR WATCH 0640 HAS NOT BEEN ISSUED YET Read more

WW 0640 Status Updates
STATUS FOR WATCH 0640 HAS NOT BEEN ISSUED YET Read more

WW 0640 Status Updates
STATUS FOR WATCH 0640 HAS NOT BEEN ISSUED YET Read more

WW 640 SEVERE TSTM ID MT 192050Z - 200400Z
URGENT - IMMEDIATE BROADCAST REQUESTED Severe Thunderstorm Watch Number 640 NWS Storm Prediction Center Norman OK 250 PM MDT Mon Aug 19 2024 The NWS Storm Prediction Center has issued a * Severe Thunderstorm Watch for portions of Northeast Idaho Western and Central Montana * Effective this Monday afternoon and evening from 250 PM until 1000 PM MDT. * Primary threats include... Scattered damaging wind gusts to 70 mph possible Isolated large hail events to 1.5 inches in diameter possible SUMMARY...Thunderstorms are forming over the mountains of northern Idaho and western Montana. These storms will intensify and organize through the afternoon and spread northeastward across the watch area. Damaging wind gusts will be possible in the strongest storms. The severe thunderstorm watch area is approximately along and 70 statute miles east and west of a line from 35 miles east southeast of Salmon ID to 35 miles northeast of Cut Bank MT. For a complete depiction of the watch see the associated watch outline update (WOUS64 KWNS WOU0). PRECAUTIONARY/PREPAREDNESS ACTIONS... REMEMBER...A Severe Thunderstorm Watch means conditions are favorable for severe thunderstorms in and close to the watch area. Persons in these areas should be on the lookout for threatening weather conditions and listen for later statements and possible warnings. Severe thunderstorms can and occasionally do produce tornadoes. && OTHER WATCH INFORMATION...CONTINUE...WW 639... AVIATION...A few severe thunderstorms with hail surface and aloft to 1.5 inches. Extreme turbulence and surface wind gusts to 60 knots. A few cumulonimbi with maximum tops to 500. Mean storm motion vector 23025. ...Hart Read more

MD 1956 CONCERNING SEVERE POTENTIAL...WATCH LIKELY FOR SOUTHEAST WYOMING...PARTS OF THE NEBRASKA PANHANDLE...AND MUCH OF EASTERN COLORADO
Mesoscale Discussion 1956 NWS Storm Prediction Center Norman OK 0219 PM CDT Mon Aug 19 2024 Areas affected...southeast Wyoming...parts of the Nebraska Panhandle...and much of eastern Colorado Concerning...Severe potential...Watch likely Valid 191919Z - 192045Z Probability of Watch Issuance...80 percent SUMMARY...Scattered strong to severe thunderstorms are expected this afternoon in the central High Plains with a threat for large hail and severe wind gusts. DISCUSSION...Moderate destabilization has occurred across eastern Colorado amid moist upslope flow (mid 60s dewpoints) and temperatures in the 80s. SPC mesoanalysis has indicated inhibition is decreasing along the Front Range. At least some inhibition is expected to remain across the Plains this afternoon which will likely limit storm initiation, however, scattered thunderstorm development is expected along the higher terrain which should intensify as it moves east into the more unstable airmass across the Plains this afternoon and evening. Mid-upper level flow of 30 to 40 knots combined with easterly flow at the surface will provide ample wind shear for some storm organization including the potential for a few supercells Despite the relatively warm temperatures aloft beneath the upper-ridge axis, steep lapse rates and the moderate shear should support some hail threat, especially early in the storm lifecycle when storm mode is more discrete. Later this afternoon and especially into the evening, expect the threat to transition to severe wind gusts with one or more clusters of storms which may develop out of the afternoon/early evening convection. ..Bentley/Hart.. 08/19/2024 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...LBF...GLD...PUB...BOU...CYS... LAT...LON 37890474 38540471 38970472 39720475 40790473 42110458 42450298 41310246 39900251 38220328 37520393 37890474 Read more

MD 1955 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR PORTIONS OF NEW ENGLAND
Mesoscale Discussion 1955 NWS Storm Prediction Center Norman OK 0125 PM CDT Mon Aug 19 2024 Areas affected...portions of New England Concerning...Severe potential...Watch unlikely Valid 191825Z - 192030Z Probability of Watch Issuance...5 percent SUMMARY...Scattered thunderstorm activity may produce strong to severe gusts through the afternoon. DISCUSSION...Thunderstorm activity ongoing along and ahead of a cold front across portions of New England has shown an uptick in coverage over the last hour. Much of the region has been under mid-level cloud cover through the morning. However, a few breaks in the clouds have allowed temperatures to warm into the 80s with MLCAPE around 500-1000 J/kg. Deep layer shear for organization remains mostly offshore, with poor low to mid-level lapse rates. A few clusters of stronger storms may produce strong to severe gusts at times. Overall, the lack of support for organization of a more widespread severe threat will keep this threat localized precluding the need to for a watch. ..Thornton/Hart.. 08/19/2024 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...GYX...BOX...BTV...OKX...ALY...PHI...BGM...CTP... LWX... LAT...LON 39177503 39167532 39297597 39877626 40557581 43067419 43987278 43997120 43827082 43107066 42647086 41797190 39317479 39177503 Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0257 PM CDT Mon Aug 19 2024 Valid 192000Z - 201200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE NORTHERN AND CENTRAL HIGH PLAINS...AND OVER WESTERN MONTANA... ...SUMMARY... Scattered severe thunderstorms are possible across portions of the northern and central High Plains, and over western Montana into tonight. Large hail and severe gusts are the primary hazards. ...20Z Update... Within the Slight Risk area over the central High Plains, 15-percent wind probabilities were added over parts of eastern CO. Here, ample diurnal heating/steepening low-level lapse rates has increased confidence in a slightly greater concentration of severe wind gusts -- especially with any clusters that evolve eastward into this evening. For more details, reference MCD #1956 and Severe Thunderstorm Watch #639. Farther north, the Slight Risk was expanded slightly eastward into western ND, where filtered diurnal heating and an eventual increase in the low-level jet should favor localized upscale growth and a continued severe-wind risk into tonight. See MCD #1958 for additional details. From portions of the Northeast into the Mid-Atlantic, scattered thunderstorms will continue tracking eastward along/ahead of a cold front through the afternoon, posing a risk of locally damaging wind gusts. The Marginal Risk was trimmed slightly behind the front in the Northeast. For details, see MCDs #1955/1957. ..Weinman.. 08/19/2024 .PREV DISCUSSION... /ISSUED 1117 AM CDT Mon Aug 19 2024/ ...High Plains... Moderately strong westerly mid-level winds are present today from MT to CO, with several weak perturbations noted on water vapor imagery within the flow. Steep mid-level lapse rates and dewpoints in the 60s will lead to a narrow corridor of favorable CAPE later today for strong/severe thunderstorm development. Clusters of convection will form over the mountains and foothills of CO/WY and spread eastward into the higher instability axis. Other areas of storms are expected to develop over the Black Hills, and across parts of eastern MT. Large hail is the main concern with these storms, although the risk of isolated damaging wind will also increase during the late afternoon and evening as outflows congeal. ...Western MT... 12z model guidance continues to agree on the development of scattered thunderstorms this afternoon over the mountains of western MT. This region will be on the eastern fringe of stronger flow aloft, and where full sunshine will aid in destabilization and steepening of low-level lapse rates. As storms move off the higher terrain, merging outflows may result in strong/damaging wind gusts in the more organized storm clusters. One mitigating factor for severe in this region would be if the persistent cloud cover east of the mountains limits destabilization. ...Southeast VA/Northeast NC... Strong daytime heating is occurring today over parts of southeast VA and northeast NC, where dewpoints in the upper 60s and 70s will yield MLCAPE values around 2000 J/kg. Scattered afternoon thunderstorms are expected. Low and mid-level winds are relatively weak today, suggesting that storms will struggle to organize. However, given the extent of heating, a few cells may occasionally pose a risk of gusty winds through the early evening. ...New England... An upper trough is moving across the Northeast US today, with the associated surface cold front tracking eastward across much of New England this afternoon. Scattered thunderstorms are expected along the front. Visible satellite imagery suggest considerable cloud cover over this region, limiting daytime heating and suppressing steeper low-level lapse rates. This should lessen the overall severe threat today. Nevertheless, a few storms could produce gusty winds and/or hail. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0257 PM CDT Mon Aug 19 2024 Valid 192000Z - 201200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE NORTHERN AND CENTRAL HIGH PLAINS...AND OVER WESTERN MONTANA... ...SUMMARY... Scattered severe thunderstorms are possible across portions of the northern and central High Plains, and over western Montana into tonight. Large hail and severe gusts are the primary hazards. ...20Z Update... Within the Slight Risk area over the central High Plains, 15-percent wind probabilities were added over parts of eastern CO. Here, ample diurnal heating/steepening low-level lapse rates has increased confidence in a slightly greater concentration of severe wind gusts -- especially with any clusters that evolve eastward into this evening. For more details, reference MCD #1956 and Severe Thunderstorm Watch #639. Farther north, the Slight Risk was expanded slightly eastward into western ND, where filtered diurnal heating and an eventual increase in the low-level jet should favor localized upscale growth and a continued severe-wind risk into tonight. See MCD #1958 for additional details. From portions of the Northeast into the Mid-Atlantic, scattered thunderstorms will continue tracking eastward along/ahead of a cold front through the afternoon, posing a risk of locally damaging wind gusts. The Marginal Risk was trimmed slightly behind the front in the Northeast. For details, see MCDs #1955/1957. ..Weinman.. 08/19/2024 .PREV DISCUSSION... /ISSUED 1117 AM CDT Mon Aug 19 2024/ ...High Plains... Moderately strong westerly mid-level winds are present today from MT to CO, with several weak perturbations noted on water vapor imagery within the flow. Steep mid-level lapse rates and dewpoints in the 60s will lead to a narrow corridor of favorable CAPE later today for strong/severe thunderstorm development. Clusters of convection will form over the mountains and foothills of CO/WY and spread eastward into the higher instability axis. Other areas of storms are expected to develop over the Black Hills, and across parts of eastern MT. Large hail is the main concern with these storms, although the risk of isolated damaging wind will also increase during the late afternoon and evening as outflows congeal. ...Western MT... 12z model guidance continues to agree on the development of scattered thunderstorms this afternoon over the mountains of western MT. This region will be on the eastern fringe of stronger flow aloft, and where full sunshine will aid in destabilization and steepening of low-level lapse rates. As storms move off the higher terrain, merging outflows may result in strong/damaging wind gusts in the more organized storm clusters. One mitigating factor for severe in this region would be if the persistent cloud cover east of the mountains limits destabilization. ...Southeast VA/Northeast NC... Strong daytime heating is occurring today over parts of southeast VA and northeast NC, where dewpoints in the upper 60s and 70s will yield MLCAPE values around 2000 J/kg. Scattered afternoon thunderstorms are expected. Low and mid-level winds are relatively weak today, suggesting that storms will struggle to organize. However, given the extent of heating, a few cells may occasionally pose a risk of gusty winds through the early evening. ...New England... An upper trough is moving across the Northeast US today, with the associated surface cold front tracking eastward across much of New England this afternoon. Scattered thunderstorms are expected along the front. Visible satellite imagery suggest considerable cloud cover over this region, limiting daytime heating and suppressing steeper low-level lapse rates. This should lessen the overall severe threat today. Nevertheless, a few storms could produce gusty winds and/or hail. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0257 PM CDT Mon Aug 19 2024 Valid 192000Z - 201200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE NORTHERN AND CENTRAL HIGH PLAINS...AND OVER WESTERN MONTANA... ...SUMMARY... Scattered severe thunderstorms are possible across portions of the northern and central High Plains, and over western Montana into tonight. Large hail and severe gusts are the primary hazards. ...20Z Update... Within the Slight Risk area over the central High Plains, 15-percent wind probabilities were added over parts of eastern CO. Here, ample diurnal heating/steepening low-level lapse rates has increased confidence in a slightly greater concentration of severe wind gusts -- especially with any clusters that evolve eastward into this evening. For more details, reference MCD #1956 and Severe Thunderstorm Watch #639. Farther north, the Slight Risk was expanded slightly eastward into western ND, where filtered diurnal heating and an eventual increase in the low-level jet should favor localized upscale growth and a continued severe-wind risk into tonight. See MCD #1958 for additional details. From portions of the Northeast into the Mid-Atlantic, scattered thunderstorms will continue tracking eastward along/ahead of a cold front through the afternoon, posing a risk of locally damaging wind gusts. The Marginal Risk was trimmed slightly behind the front in the Northeast. For details, see MCDs #1955/1957. ..Weinman.. 08/19/2024 .PREV DISCUSSION... /ISSUED 1117 AM CDT Mon Aug 19 2024/ ...High Plains... Moderately strong westerly mid-level winds are present today from MT to CO, with several weak perturbations noted on water vapor imagery within the flow. Steep mid-level lapse rates and dewpoints in the 60s will lead to a narrow corridor of favorable CAPE later today for strong/severe thunderstorm development. Clusters of convection will form over the mountains and foothills of CO/WY and spread eastward into the higher instability axis. Other areas of storms are expected to develop over the Black Hills, and across parts of eastern MT. Large hail is the main concern with these storms, although the risk of isolated damaging wind will also increase during the late afternoon and evening as outflows congeal. ...Western MT... 12z model guidance continues to agree on the development of scattered thunderstorms this afternoon over the mountains of western MT. This region will be on the eastern fringe of stronger flow aloft, and where full sunshine will aid in destabilization and steepening of low-level lapse rates. As storms move off the higher terrain, merging outflows may result in strong/damaging wind gusts in the more organized storm clusters. One mitigating factor for severe in this region would be if the persistent cloud cover east of the mountains limits destabilization. ...Southeast VA/Northeast NC... Strong daytime heating is occurring today over parts of southeast VA and northeast NC, where dewpoints in the upper 60s and 70s will yield MLCAPE values around 2000 J/kg. Scattered afternoon thunderstorms are expected. Low and mid-level winds are relatively weak today, suggesting that storms will struggle to organize. However, given the extent of heating, a few cells may occasionally pose a risk of gusty winds through the early evening. ...New England... An upper trough is moving across the Northeast US today, with the associated surface cold front tracking eastward across much of New England this afternoon. Scattered thunderstorms are expected along the front. Visible satellite imagery suggest considerable cloud cover over this region, limiting daytime heating and suppressing steeper low-level lapse rates. This should lessen the overall severe threat today. Nevertheless, a few storms could produce gusty winds and/or hail. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0257 PM CDT Mon Aug 19 2024 Valid 192000Z - 201200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE NORTHERN AND CENTRAL HIGH PLAINS...AND OVER WESTERN MONTANA... ...SUMMARY... Scattered severe thunderstorms are possible across portions of the northern and central High Plains, and over western Montana into tonight. Large hail and severe gusts are the primary hazards. ...20Z Update... Within the Slight Risk area over the central High Plains, 15-percent wind probabilities were added over parts of eastern CO. Here, ample diurnal heating/steepening low-level lapse rates has increased confidence in a slightly greater concentration of severe wind gusts -- especially with any clusters that evolve eastward into this evening. For more details, reference MCD #1956 and Severe Thunderstorm Watch #639. Farther north, the Slight Risk was expanded slightly eastward into western ND, where filtered diurnal heating and an eventual increase in the low-level jet should favor localized upscale growth and a continued severe-wind risk into tonight. See MCD #1958 for additional details. From portions of the Northeast into the Mid-Atlantic, scattered thunderstorms will continue tracking eastward along/ahead of a cold front through the afternoon, posing a risk of locally damaging wind gusts. The Marginal Risk was trimmed slightly behind the front in the Northeast. For details, see MCDs #1955/1957. ..Weinman.. 08/19/2024 .PREV DISCUSSION... /ISSUED 1117 AM CDT Mon Aug 19 2024/ ...High Plains... Moderately strong westerly mid-level winds are present today from MT to CO, with several weak perturbations noted on water vapor imagery within the flow. Steep mid-level lapse rates and dewpoints in the 60s will lead to a narrow corridor of favorable CAPE later today for strong/severe thunderstorm development. Clusters of convection will form over the mountains and foothills of CO/WY and spread eastward into the higher instability axis. Other areas of storms are expected to develop over the Black Hills, and across parts of eastern MT. Large hail is the main concern with these storms, although the risk of isolated damaging wind will also increase during the late afternoon and evening as outflows congeal. ...Western MT... 12z model guidance continues to agree on the development of scattered thunderstorms this afternoon over the mountains of western MT. This region will be on the eastern fringe of stronger flow aloft, and where full sunshine will aid in destabilization and steepening of low-level lapse rates. As storms move off the higher terrain, merging outflows may result in strong/damaging wind gusts in the more organized storm clusters. One mitigating factor for severe in this region would be if the persistent cloud cover east of the mountains limits destabilization. ...Southeast VA/Northeast NC... Strong daytime heating is occurring today over parts of southeast VA and northeast NC, where dewpoints in the upper 60s and 70s will yield MLCAPE values around 2000 J/kg. Scattered afternoon thunderstorms are expected. Low and mid-level winds are relatively weak today, suggesting that storms will struggle to organize. However, given the extent of heating, a few cells may occasionally pose a risk of gusty winds through the early evening. ...New England... An upper trough is moving across the Northeast US today, with the associated surface cold front tracking eastward across much of New England this afternoon. Scattered thunderstorms are expected along the front. Visible satellite imagery suggest considerable cloud cover over this region, limiting daytime heating and suppressing steeper low-level lapse rates. This should lessen the overall severe threat today. Nevertheless, a few storms could produce gusty winds and/or hail. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0257 PM CDT Mon Aug 19 2024 Valid 192000Z - 201200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE NORTHERN AND CENTRAL HIGH PLAINS...AND OVER WESTERN MONTANA... ...SUMMARY... Scattered severe thunderstorms are possible across portions of the northern and central High Plains, and over western Montana into tonight. Large hail and severe gusts are the primary hazards. ...20Z Update... Within the Slight Risk area over the central High Plains, 15-percent wind probabilities were added over parts of eastern CO. Here, ample diurnal heating/steepening low-level lapse rates has increased confidence in a slightly greater concentration of severe wind gusts -- especially with any clusters that evolve eastward into this evening. For more details, reference MCD #1956 and Severe Thunderstorm Watch #639. Farther north, the Slight Risk was expanded slightly eastward into western ND, where filtered diurnal heating and an eventual increase in the low-level jet should favor localized upscale growth and a continued severe-wind risk into tonight. See MCD #1958 for additional details. From portions of the Northeast into the Mid-Atlantic, scattered thunderstorms will continue tracking eastward along/ahead of a cold front through the afternoon, posing a risk of locally damaging wind gusts. The Marginal Risk was trimmed slightly behind the front in the Northeast. For details, see MCDs #1955/1957. ..Weinman.. 08/19/2024 .PREV DISCUSSION... /ISSUED 1117 AM CDT Mon Aug 19 2024/ ...High Plains... Moderately strong westerly mid-level winds are present today from MT to CO, with several weak perturbations noted on water vapor imagery within the flow. Steep mid-level lapse rates and dewpoints in the 60s will lead to a narrow corridor of favorable CAPE later today for strong/severe thunderstorm development. Clusters of convection will form over the mountains and foothills of CO/WY and spread eastward into the higher instability axis. Other areas of storms are expected to develop over the Black Hills, and across parts of eastern MT. Large hail is the main concern with these storms, although the risk of isolated damaging wind will also increase during the late afternoon and evening as outflows congeal. ...Western MT... 12z model guidance continues to agree on the development of scattered thunderstorms this afternoon over the mountains of western MT. This region will be on the eastern fringe of stronger flow aloft, and where full sunshine will aid in destabilization and steepening of low-level lapse rates. As storms move off the higher terrain, merging outflows may result in strong/damaging wind gusts in the more organized storm clusters. One mitigating factor for severe in this region would be if the persistent cloud cover east of the mountains limits destabilization. ...Southeast VA/Northeast NC... Strong daytime heating is occurring today over parts of southeast VA and northeast NC, where dewpoints in the upper 60s and 70s will yield MLCAPE values around 2000 J/kg. Scattered afternoon thunderstorms are expected. Low and mid-level winds are relatively weak today, suggesting that storms will struggle to organize. However, given the extent of heating, a few cells may occasionally pose a risk of gusty winds through the early evening. ...New England... An upper trough is moving across the Northeast US today, with the associated surface cold front tracking eastward across much of New England this afternoon. Scattered thunderstorms are expected along the front. Visible satellite imagery suggest considerable cloud cover over this region, limiting daytime heating and suppressing steeper low-level lapse rates. This should lessen the overall severe threat today. Nevertheless, a few storms could produce gusty winds and/or hail. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0257 PM CDT Mon Aug 19 2024 Valid 192000Z - 201200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE NORTHERN AND CENTRAL HIGH PLAINS...AND OVER WESTERN MONTANA... ...SUMMARY... Scattered severe thunderstorms are possible across portions of the northern and central High Plains, and over western Montana into tonight. Large hail and severe gusts are the primary hazards. ...20Z Update... Within the Slight Risk area over the central High Plains, 15-percent wind probabilities were added over parts of eastern CO. Here, ample diurnal heating/steepening low-level lapse rates has increased confidence in a slightly greater concentration of severe wind gusts -- especially with any clusters that evolve eastward into this evening. For more details, reference MCD #1956 and Severe Thunderstorm Watch #639. Farther north, the Slight Risk was expanded slightly eastward into western ND, where filtered diurnal heating and an eventual increase in the low-level jet should favor localized upscale growth and a continued severe-wind risk into tonight. See MCD #1958 for additional details. From portions of the Northeast into the Mid-Atlantic, scattered thunderstorms will continue tracking eastward along/ahead of a cold front through the afternoon, posing a risk of locally damaging wind gusts. The Marginal Risk was trimmed slightly behind the front in the Northeast. For details, see MCDs #1955/1957. ..Weinman.. 08/19/2024 .PREV DISCUSSION... /ISSUED 1117 AM CDT Mon Aug 19 2024/ ...High Plains... Moderately strong westerly mid-level winds are present today from MT to CO, with several weak perturbations noted on water vapor imagery within the flow. Steep mid-level lapse rates and dewpoints in the 60s will lead to a narrow corridor of favorable CAPE later today for strong/severe thunderstorm development. Clusters of convection will form over the mountains and foothills of CO/WY and spread eastward into the higher instability axis. Other areas of storms are expected to develop over the Black Hills, and across parts of eastern MT. Large hail is the main concern with these storms, although the risk of isolated damaging wind will also increase during the late afternoon and evening as outflows congeal. ...Western MT... 12z model guidance continues to agree on the development of scattered thunderstorms this afternoon over the mountains of western MT. This region will be on the eastern fringe of stronger flow aloft, and where full sunshine will aid in destabilization and steepening of low-level lapse rates. As storms move off the higher terrain, merging outflows may result in strong/damaging wind gusts in the more organized storm clusters. One mitigating factor for severe in this region would be if the persistent cloud cover east of the mountains limits destabilization. ...Southeast VA/Northeast NC... Strong daytime heating is occurring today over parts of southeast VA and northeast NC, where dewpoints in the upper 60s and 70s will yield MLCAPE values around 2000 J/kg. Scattered afternoon thunderstorms are expected. Low and mid-level winds are relatively weak today, suggesting that storms will struggle to organize. However, given the extent of heating, a few cells may occasionally pose a risk of gusty winds through the early evening. ...New England... An upper trough is moving across the Northeast US today, with the associated surface cold front tracking eastward across much of New England this afternoon. Scattered thunderstorms are expected along the front. Visible satellite imagery suggest considerable cloud cover over this region, limiting daytime heating and suppressing steeper low-level lapse rates. This should lessen the overall severe threat today. Nevertheless, a few storms could produce gusty winds and/or hail. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0257 PM CDT Mon Aug 19 2024 Valid 192000Z - 201200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE NORTHERN AND CENTRAL HIGH PLAINS...AND OVER WESTERN MONTANA... ...SUMMARY... Scattered severe thunderstorms are possible across portions of the northern and central High Plains, and over western Montana into tonight. Large hail and severe gusts are the primary hazards. ...20Z Update... Within the Slight Risk area over the central High Plains, 15-percent wind probabilities were added over parts of eastern CO. Here, ample diurnal heating/steepening low-level lapse rates has increased confidence in a slightly greater concentration of severe wind gusts -- especially with any clusters that evolve eastward into this evening. For more details, reference MCD #1956 and Severe Thunderstorm Watch #639. Farther north, the Slight Risk was expanded slightly eastward into western ND, where filtered diurnal heating and an eventual increase in the low-level jet should favor localized upscale growth and a continued severe-wind risk into tonight. See MCD #1958 for additional details. From portions of the Northeast into the Mid-Atlantic, scattered thunderstorms will continue tracking eastward along/ahead of a cold front through the afternoon, posing a risk of locally damaging wind gusts. The Marginal Risk was trimmed slightly behind the front in the Northeast. For details, see MCDs #1955/1957. ..Weinman.. 08/19/2024 .PREV DISCUSSION... /ISSUED 1117 AM CDT Mon Aug 19 2024/ ...High Plains... Moderately strong westerly mid-level winds are present today from MT to CO, with several weak perturbations noted on water vapor imagery within the flow. Steep mid-level lapse rates and dewpoints in the 60s will lead to a narrow corridor of favorable CAPE later today for strong/severe thunderstorm development. Clusters of convection will form over the mountains and foothills of CO/WY and spread eastward into the higher instability axis. Other areas of storms are expected to develop over the Black Hills, and across parts of eastern MT. Large hail is the main concern with these storms, although the risk of isolated damaging wind will also increase during the late afternoon and evening as outflows congeal. ...Western MT... 12z model guidance continues to agree on the development of scattered thunderstorms this afternoon over the mountains of western MT. This region will be on the eastern fringe of stronger flow aloft, and where full sunshine will aid in destabilization and steepening of low-level lapse rates. As storms move off the higher terrain, merging outflows may result in strong/damaging wind gusts in the more organized storm clusters. One mitigating factor for severe in this region would be if the persistent cloud cover east of the mountains limits destabilization. ...Southeast VA/Northeast NC... Strong daytime heating is occurring today over parts of southeast VA and northeast NC, where dewpoints in the upper 60s and 70s will yield MLCAPE values around 2000 J/kg. Scattered afternoon thunderstorms are expected. Low and mid-level winds are relatively weak today, suggesting that storms will struggle to organize. However, given the extent of heating, a few cells may occasionally pose a risk of gusty winds through the early evening. ...New England... An upper trough is moving across the Northeast US today, with the associated surface cold front tracking eastward across much of New England this afternoon. Scattered thunderstorms are expected along the front. Visible satellite imagery suggest considerable cloud cover over this region, limiting daytime heating and suppressing steeper low-level lapse rates. This should lessen the overall severe threat today. Nevertheless, a few storms could produce gusty winds and/or hail. Read more