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SPC Aug 19, 2024 1730 UTC Day 2 Convective Outlook

1 year 1 month ago

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1209 PM CDT Mon Aug 19 2024 Valid 201200Z - 211200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FOR MUCH OF MONTANA INTO PARTS OF THE NORTHERN/CENTRAL HIGH PLAINS... ...SUMMARY... Widely scattered to scattered storms are possible in parts of central/eastern Montana with more isolated coverage into parts of the central High Plains on Tuesday. Severe winds and large hail are the primary threats. ...Synopsis... An upper-level trough will remain in the Northwest and make slow progress eastward. A modest surface trough will develop in the northern and central High Plains. The upper-level ridge will amplify slightly in the central U.S. Surface high pressure will be centered in the Great Lakes with offshore flow expected across much of the eastern U.S. Some moisture return is possible along the western flank of the surface high in the High Plains region. ...Montana... Widely scattered to scattered thunderstorms are expected to develop within the terrain of southwestern and south-central Montana during the afternoon. This activity is expected to progress to the northeast into the evening. Initial storms will likely be discrete, but rather large temperature-dewpoint spreads should promote outflow dominant storms that will tend to grow upscale quickly. Severe winds are expected to be the primary hazard, but steep mid-level lapse rates and 40-50 kts of effective shear would support some risk of large hail with the strongest discrete storms. Buoyancy will be minimal within the higher terrain and perhaps reach 1000-1500 J/kg in central Montana. Greater buoyancy will exist into eastern Montana, but MLCIN will also be greater. While a narrow area of greater severe wind potential could develop, the spatial extent appears to low/uncertain for an increase in severe probabilities. ...Black Hills into western Nebraska... Though uncertainty in initiation is high due to weak forcing, an isolated storm or two could develop within the surface trough during the afternoon. Northwesterly flow aloft will be sufficient for 35-40 kts of effective shear. 1500-2500 J/kg MLCAPE is possible by the afternoon. Isolated wind damage and large hail could occur should a storm develop and mature. ..Wendt.. 08/19/2024 Read more

SPC Aug 19, 2024 1730 UTC Day 2 Convective Outlook

Severe Storms

1 year 1 month ago

SPC Day 1 Fire Weather Outlook

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1117 AM CDT Mon Aug 19 2024 Valid 191630Z - 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 later today across portions of the northern and central High Plains, and over western Montana. Large hail and severe gusts are the primary hazards. ...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. ..Hart/Thornton.. 08/19/2024 Read more