SPC Dec 21, 2023 1730 UTC Day 2 Convective Outlook

[NorthGeorgiaWX]

SPC 1730Z Day 2 Outlook

Day 2 Convective Outlook  
NWS Storm Prediction Center Norman OK
1126 AM CST Thu Dec 21 2023

Valid 221200Z - 231200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
SOUTHERN ARIZONA AND FAR SOUTHWEST NEW MEXICO...

...SUMMARY...
Thunderstorms will be possible Friday from southern California
across much of the Southwest. Some hail and strong/gusty winds may
occur over parts of southern Arizona and far southwest New Mexico
Friday afternoon and evening.

...Southwest...
A closed upper low initially centered off the coast of southern CA
will move eastward Friday across the northern Baja Peninsula and
lower CO River Valley. Large-scale ascent preceding this feature and
associated mid-level moisture will support showers and thunderstorms
from southern CA into much of the Southwest through the period.
Widespread cloudiness and limited low-level moisture should hinder
the development of much instability. But modest daytime heating and
cooling mid-level temperatures as the upper trough/low advances
eastward may aid weak buoyancy across parts of southern AZ and
vicinity by Friday afternoon.

Assuming this weak instability can develop, strengthening mid-level
southwesterly flow ahead of the upper trough/low will support
deep-layer shear increasing to 35-50 kt by late Friday afternoon and
early evening. Some guidance shows the potential for a supercell or
two to track northeastward from northern Mexico across parts of
southern AZ and perhaps into far southwest NM. If this occurs, then
isolated hail will be possible given cold mid-level temperatures and
favorable effective bulk shear. The potential for occasional
strong/gusty winds may also exist where the boundary layer can
become well mixed as low-level lapse rates steepen and modest
diurnal heating occurs. Overall confidence in severe potential
across parts of the Southwest Friday remains low, as instability is
expected to remain rather weak.

..Gleason.. 12/21/2023

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