SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1129 AM CST Thu Dec 10 2020 Valid 111200Z - 121200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS CENTRAL AND EAST TX INTO PORTIONS OF SOUTHEAST OK...WESTERN/CENTRAL AR...AND NORTHWEST LA... ...SUMMARY... Thunderstorms associated with marginally severe wind gusts will be possible on Friday across parts of central/east Texas, southeast Oklahoma, western/central Arkansas, and northwest Louisiana. ...Synopsis... A broad and deep upper trough is forecast to be in place across the western and central CONUS early Friday morning. An embedded lead shortwave trough will likely be centered over the central and northern southern Plains with another shortwave trough farther west over the Four Corners region. The lead shortwave will likely dampen as it moves northeastward within more confluent flow. The Four Corners shortwave is expected to continue eastward into the central/southern Plains while becoming increasingly negatively tilted. At the surface, a low associated with the lead shortwave will likely be centered over central OK. A cold front will extend northeastward from this low into Lower MI and southwestward into the southern TX Panhandle. Northern portion of this front will make modest southeastward progress throughout the day while the surface low tracks gradually northeastward along it. Expectation is for the surface low to end the period over IL. Southern portion of the front will sweep southeastward/eastward across eastern OK, north/central TX, and the Arklatex, ending the period over the Lower MS Valley. ...Central/North-Central/East TX into the Arklatex... A broad warm sector with isolated thunderstorms is expected to cover much of central and eastern TX/OK early Friday morning, ahead of the second, stronger Four Corners shortwave trough mentioned in synopsis. Modest low-level moisture advection is anticipated throughout the day within this warm sector, with mid 50s dewpoints likely reaching into southeast OK and central OK. Any 60s dewpoints will likely stay south of the TX/OK Red River border. Enough low-level moisture will likely be present for modest elevated instability (for parcels rooted around 850-mb) and continued potential for a few thunderstorms within the warm sector. However, severe potential will be limited by the elevated nature of the storms and transient updraft character promoted by modest instability. Even so, some severe potential may be realized later in the afternoon and evening as the cold front pushes across the region. The increased potential for surface-based storms coupled with strengthening wind fields (particularly around 850-mb) could result in updrafts deep and persistent enough to produce damaging wind gusts. Tornado threat currently appears less than 2% due to lack of potential within the warm sector and more favored linear mode along the front. Additionally, there is a low probability (i.e. lower than 5%) for updrafts strong enough to produce hail along the front in north-central/northeast TX. This threat will depend on just how much filtered daytime heating can be realized between the warm conveyor belt and the approaching cold front. Higher confidence in these mesoscale details could result in the inclusion of hail probabilities in later forecasts. ..Mosier.. 12/10/2020
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