SPC 1730Z Day 2 Outlook

Day 2 Outlook Image

Day 2 Convective Outlook  
NWS Storm Prediction Center Norman OK
1128 AM CST Sat Nov 14 2020

Valid 151200Z - 161200Z


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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