SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1128 AM CST Sat Nov 14 2020 Valid 151200Z - 161200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... The threat for thunderstorms is expected to remain fairly low across parts of the Ohio Valley, Mid-Atlantic, and southern New England Sunday into Sunday night, though strong/gusty winds may still occur with shallow convection. ...Ohio Valley into the Mid-Atlantic and Southern New England... A shortwave trough is forecast to progress eastward across the OH Valley, Great Lakes, Mid-Atlantic, and New England on Sunday. A deep surface low associated with this shortwave trough should develop northeastward into Ontario/Quebec through the period. A trailing cold front will sweep quickly eastward across parts of the OH Valley, Mid-Atlantic, and New England through Sunday evening. Limited low-level moisture return should occur ahead of the front, with low 50s surface dewpoints possibly extending into parts of southern NY/New England by late Sunday afternoon. Poor mid-level lapse rates and modest diurnal heating owing to widespread cloudiness are generally expected to limit instability through the day. Consensus of latest guidance suggests that no more than 100-200 J/kg of surface-based instability may develop ahead of the front by peak afternoon heating, mainly from parts of eastern PA into NJ, MD, northern VA, and the Delmarva Peninsula. With that said, the low to mid-level flow field is expected to be quite strong, with 50-60+ kt of south-southwesterly winds present only 1-2 km above the surface. Latest convection-allowing model guidance is in general agreement that a shallow convective line will develop along the front and quickly advance eastward across portions of the Mid-Atlantic and perhaps southern New England through early Sunday evening. It is possible that strong/gusty winds may reach the surface across these regions through convective downdraft processes, even through the convection may remain too shallow to support lightning flashes. Low probabilities for severe/damaging wind gusts may need to be introduced in a later outlook if confidence increases in sufficient instability being realized. ..Gleason.. 11/14/2020
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