SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1139 PM CST Mon Dec 28 2020 Valid 291200Z - 301200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Organized severe thunderstorms are not anticipated. ...Southern Plains... Positive-tilt upper trough is digging southeast across southern CA late this evening and should settle into northern Mexico during the latter half of the period. The strongest 500mb flow will not translate through the base of the trough until later day2 into day3 which will allow this feature to eject toward south TX at that time. Prior to this trough ejecting northeast, weak mid-level height falls will overspread the Plains which should encourage a weak lee surface low to migrate off the CO High Plains into the Edwards Plateau during the overnight hours. Strengthening LLJ across TX is expected to aid northward movement of modified Gulf moisture such that upper 50s surface dew points will return to northwest TX into extreme southwest OK by 30/00z. While the latest model guidance suggests the strongest boundary-layer heating will be noted across this region, convection may struggle to organize until the cold front surges south during the late evening. Prior to the frontal forcing, warm advection will be the primary mechanism for scattered weak convection across the southern Plains. Forecast soundings across northwest TX after sunset suggest near-surface based buoyancy is likely, however instability should remain weak given the modest lapse rates. Even so, organized convection should ultimately evolve along/immediately behind the front as it surges south, encouraged by southerly 850mb flow atop the front. While small hail and perhaps some gusty winds could accompany the most organized storms, weak instability should limit the overall severe threat. ..Darrow/Wendt.. 12/29/2020
There’s more click here.