SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1031 AM CST Sat Dec 04 2021 Valid 041630Z - 051200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Isolated thunderstorms are possible across a wide area from north Texas and southern Oklahoma, through parts of the mid South. ...Synopsis... In the mid levels, a split flow regime with moderate to strong northwesterly flow was observed across the northern third of the CONUS. Several vorticity maxima and their associated jet streaks within the mostly zonal flow field will move east with time today, supporting several areas of wintry precipitation from the Pacific Northwest/northern Rockies into the Northeast. Within the weaker southern branch of the mid-level westerlies, an upper low over the Southwest will linger through the forecast period while a weak shortwave trough moves east along the Gulf Coast. At the surface, a stalled front and weak low from eastern Oklahoma and north Texas into Alabama will support increased ascent and moistening through the forecast period. ...Southern Plains and portions of the Southeast... As low-level moisture and weak ascent increase through the period, Isolated thunderstorms may develop through the forecast period across several areas. Weak isentropic ascent along the front through the Gulf coast and central Alabama may support a few thunderstorms as diurnal warming and moistening contribute to a weakly unstable (MUcape around 500 J/kg) environment. The greatest focus for warm and moist ascent appears likely across portions of north Texas and eastern Oklahoma into southern Arkansas late in the period, as a low-level jet and upstream shortwave trough support isolated thunderstorm development overnight. Continued low-level warm advection should result in low 60s F surface dewpoints reaching into southern Arkansas by 06z. Cooling temperatures aloft ahead of the southern branch shortwave should favor modest lapse rates around 6.5 C/km aiding in weak to moderate destabilization. With MUCAPE around 500-100 J/kg, and weak mid-level flow, a few pule type storms with small hail may develop. However, forecast coverage is expected to remain below thresholds for severe probabilities. ..Lyons/Hart.. 12/04/2021 Read more LIVE: spc.noaa.gov
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