SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0617 AM CST Mon Jan 11 2021 Valid 111300Z - 121200Z ...NO THUNDERSTORM AREAS FORECAST... ...SUMMARY... The risk for thunderstorms appears negligible across much of the nation today through tonight. ...Synopsis... In mid/upper levels, a split-flow pattern is apparent over the CONUS. The northern stream crosses the northern part of a strongly positively tilted mean trough that extends from the Great Lakes across the southern Plains to northern Baja. Meanwhile the southern stream jet curves around the trough's base across northwestern/ north-central MX and the Gulf Coast States. While the mean trough will remain nearly in place through the period, its geometry will adjust in response to two associated shortwaves: 1. A leading perturbation now manifest as a compact cyclone over eastern OK, northeast TX and parts of AR. This feature will eject/accelerate east-northeastward into a broader confluent-flow regime, crossing the southern Appalachians overnight as a weakening, positively tilted, open wave. 2. Trailing vorticity lobes -- initially over the Four Corners area and between LAS-EED -- that should phase with each other and form a pronounced trough from west TX across southern NM and northwestern MX by 12Z tomorrow. At the surface, 11Z analysis depicted a low, associated with the leading mid/upper perturbation, near the mouth of the Mississippi River, with cold front southwestward over the west-central Gulf and warm front southeastward toward western Cuba. In keeping with the forecast trend of the wave aloft, the low should remain weak as it moves east-northeastward across the FL Panhandle and southern GA through the period, into cooler boundary-layer air. Marginal elevated buoyancy may brush the coastline of the western/central FL Panhandle today, and lightning cannot be ruled out. However, with more-favorable thermodynamic support remaining over the Gulf, and lift at all scales weakening with time, the potential appears too brief, isolated and conditional for a 10%/general thunderstorm outlook over land. ..Edwards/Mosier.. 01/11/2021
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