Subj : DAY48SVR: Nws Storm Prediction Center Norman Ok
To   : wx-storm@lists.illinois.edu
From : COD Weather Processor
Date : Fri Dec 09 2022 10:18:55

ACUS48 KWNS 091018
SWOD48
SPC AC 091017

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0417 AM CST Fri Dec 09 2022

Valid 121200Z - 171200Z

....DISCUSSION...
Medium-range models, and their corresponding ensembles, continue to
depict a scenario fairly consistent with runs over the past couple
of days, with perhaps a slightly slower evolution of the progression
of the substantial upper trough/low.  This feature is progged to
move across the Rockies Day 4/Monday, the central Plains Day
5/Tuesday, and then the Mid Missouri Valley Day 6/Wednesday, before
traversing the Midwest/Ohio Valley Day 7 and then the Central
Appalachians Day 8.

Day 4/Monday, as ascent increases across the southern Plains as
suggested by the onset of mid-level height falls, elevated
convection will evolve across the central and into the southern
Plains.  Even south of the Red River, storms should remain largely
atop a shallow surface-based stable layer, suggesting that any
severe risk should be in the form of hail, and appearing
insufficient at this time to continue with the 15% risk area.

Day 5/Tuesday, progression of the front across the southern Plains
will occur, reaching the Ozarks/Arklatex/East Texas area by early
evening.  Ahead of the front, strong southerly winds will advect
seasonably rich Gulf moisture northward, likely resulting in
sufficient instability for the development of severe/supercell
storms.  At this time, the greatest risk remains apparent from
roughly the Arklatex region eastward straddling the
Arkansas/Louisiana border, where very strong/veering flow with
height should combine with ample CAPE to yield all-hazards severe
risk, including tornado potential.

Severe risk will likely continue overnight and into Day 6/Wednesday,
though a persistent antecedent surface high/cold air damming into
the southern Appalachians should suppress instability -- and thus
severe potential -- progressively farther southward as storms shift
eastward across the Gulf Coast states through the day.  Still,
all-hazards severe risk is apparent across southern parts of
Mississippi and Alabama, and into the Florida Panhandle overnight,
warranting inclusion of a 15% area for Day 6.

Day 7/Thursday, persistence of the damming high should continue to
suppress instability southward.  While some severe risk could
locally evolve across the Florida Peninsula, potential appears too
low to warrant areal inclusion.

With the front currently expected to move offshore overnight
Thursday or early Friday, severe weather potential should shift away
from the mainland.

...Goss.. 12/09/2022

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