Subj : DAY48SVR: Nws Storm Prediction Center Norman Ok
To   : wx-storm@lists.illinois.edu
From : COD Weather Processor
Date : Sun Dec 04 2022 10:10:15

ACUS48 KWNS 041010
SWOD48
SPC AC 041008

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0408 AM CST Sun Dec 04 2022

Valid 071200Z - 121200Z

....DISCUSSION...
Current model runs exhibit reasonable consistency Days 4-5
(Wednesday and Thursday), as a western U.S. system ejects eastward
into/across the Plains.  By Friday/Day 6, timing/location deviations
become fairly pronounced, precluding any convective assessment
through the latter half of the period.

In the meantime, as the trough crosses the West Day 4/Wednesday, and
begins shifting into the Plains overnight, central U.S. surface
cyclogenesis is expected.  However, more appreciable moisture return
is not anticipated until Day 5/Thursday.

On Thursday, a deepening surface low is forecast to be moving across
the lower Missouri and into the Ohio Valley, with a cold front
trailing southwestward into eastern Texas.  With several days of
boundary layer airmass modification over the Gulf to occur with a
lack of an intervening frontal passage, a seasonably moist airmass
will advect northward across the warm sector.  However, lapse rates
appear likely to remain quite weak, and thus CAPE would at this time
appear likely to remain minimal at best.  Still, very favorable
shear is expected, supportive of both rotating storms, or damaging
wind potential depending upon amount -- and mode -- of convection.
With that said, will opt not to introduce 15% risk area at this
time, due to the thermodynamic uncertainties.  However, an areal
inclusion may be needed in subsequent outlooks -- particularly if
models remain consistent in terms of system strength and associated
theta-e advection across the warm sector.

Beyond Day 5, models begin to diverge in terms of timing/location of
the upper system and associated surface low/front, precluding
confidence in assessing any convective potential through the
remainder of the period.

...Goss.. 12/04/2022

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