SPC 1200Z Day 1 Outlook

Day 1 Outlook Image

Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
1148 PM CST Fri Nov 20 2020

Valid 211200Z - 221200Z


The risk for severe thunderstorms appears negligible across the U.S.
through tonight.

A shortwave trough is forecast to amplify and move southeastward
from the northern Rockies this morning into the central Plains by
late tonight. At the surface, a cold front will sag southward across
the southern Plains and Ozark Plateau, as a weak surface wave
develops along the boundary and moves northeastward toward the
mid-MS Valley by Sunday morning. 

...South-central Plains into the Ozark Plateau/Mid-MS Valley...
In advance of the primary shortwave trough moving into the central
Plains, one or more lower-amplitude vorticity maxima will likely
traverse the central Plains into the mid-MS Valley this afternoon
into tonight. Ascent attendant to these features will likely result
in the development of primarily elevated convection to the north of
the cold front. The most robust convection is currently anticipated
from northeast OK into the Ozark Plateau this evening, where modest
low-level moisture and relatively steep midlevel lapse rates may
support MUCAPE up to 500 J/kg. Small hail may occur with the
strongest storms, but the severe risk appears low at this time.
Convection should spread into the mid-MS Valley late tonight.

...South FL...
While very dry air aloft and a warm layer based roughly around 700
mb will continue to suppress attempts at deep convection during much
of the day, a gradual increase in moisture/instability across south
FL may support the potential for isolated thunderstorm development
by late afternoon/evening, primarily across the southeast portion of
the peninsula.

..Dean.. 11/21/2020

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