SPC 2000Z Day 1 Outlook

Day 1 Outlook Image

Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
0146 PM CST Sat Nov 21 2020

Valid 212000Z - 221200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Severe thunderstorms are not expected today or tonight.

...20Z Update...
Recent surface analysis places a low over northeast OK, with a cold
front extending southwestward from this low back across the southern
TX Panhandle and into southeast NM. The cold front also extends
east-northeastward across northern AR and into the TN Valley. Modest
warm-air advection across the western portion of this frontal zone
will continue to contribute to showers and occasional thunderstorms
from northern OK through the Ozark Plateau. This corridor of showers
and thunderstorms will gradually shift southward as the cold front
moves southward throughout the remainder of the period.

..Mosier.. 11/21/2020

.PREV DISCUSSION... /ISSUED 1017 AM CST Sat Nov 21 2020/

...Synopsis...
A series of low-amplitude shortwave troughs will move eastward from
the Four Corners to the lower OH Valley, in advance of an amplifying
northern stream trough over the upper-middle MO Valley.  The
northward return of boundary-layer dewpoints in the low-mid 60s
across east TX will contribute to weak buoyancy along a frontal zone
from southern OK into the Ozarks.  A few elevated thunderstorms are
expected later today into tonight atop the frontal surface, in
association with embedded speed maxima progressing eastward from
northern NM/southern CO.  Other isolated thunderstorms may also
occur this afternoon into tonight along the path of the embedded
speed maxima, originating with weak buoyancy over the higher terrain
over northern NM/southern CO and spreading eastward above the
shallow cool air mass over the southern High Plains.

Otherwise, continued low-level air mass modification and some
cooling in the 850-700 mb layer noted from 00z to 12z at Miami may
allow sufficiently deep convection for isolated lightning flashes
near the southeast FL coast.

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