SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1115 PM CST Sun Nov 22 2020 Valid 231200Z - 241200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Scattered thunderstorms are possible across portions of New England and over areas of the Rockies/Plains. ...New England... Strong mid-level speed max is digging southeast across WI late this evening. This feature will encourage height falls across New England as a strong short-wave trough advances into the upper OH Valley by the start of the day1 period. In response, sustained southerly low-level flow will allow modified boundary-layer moisture to advance inland across coastal southern New England such that weak surface-based buoyancy should materialize during the first few hours of the convective period. Forecast soundings from southeast CT/RI/southeast MA exhibit upwards of 300 J/kg SBCAPE within a poor lapse rate environment that is strongly sheared. Very strong flow should be noted just off the surface but poor lapse rates and weak buoyancy do not favor efficient mixing of stronger flow aloft to the surface; however, gusty winds could accompany convection very early in the period. ...Rockies/Plains... Heights will lower considerably across the Four Corners region during the latter half of the period as a 90kt+ 500mb speed max digs into southeast AZ. This evolving trough should induce/maintain a notable LLJ across the High Plains which will result in a warm front advancing north to a position along the KS/NE border by 24/12z. Cooling profiles and steepening lapse rates suggest some lightning potential with the strongest convection. ..Darrow/Jirak.. 11/23/2020
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