Subj : DAY48SVR: Nws Storm Prediction Center Norman Ok
To   : wx-storm@lists.illinois.edu
From : COD Weather Processor
Date : Wed Feb 22 2023 09:01:22

ACUS48 KWNS 220901
SWOD48
SPC AC 220900

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0300 AM CST Wed Feb 22 2023

Valid 251200Z - 021200Z

....DISCUSSION...
On Saturday/D4, an upper low will move across southern CA late in
the day, reaching the lower CO Valley early on Sunday/D5. Meanwhile,
temporary upper ridging will occur over the Plains with a broad
expanse of northwesterlies across the East. Southerly surface winds
will increase Saturday/D4 night across the western Gulf of Mexico
and TX, aiding moisture advection northward. While instability will
begin to develop over western TX and OK, severe thunderstorms are
not expected Saturday/D4.

On Sunday/D5, the upper trough will accelerate eastward across NM,
reaching the southern High Plains by 00Z Monday. Strong
southwesterly midlevel winds of 70-90 kt will emerge, as low
pressure rapidly deepens over eastern CO/western KS. A dryline will
extend south from the low into west TX, followed closely by a
prominent cold front.

As dewpoints in the lower 60s F surge north toward the low, MUCAPE
of 500-1000 J/kg is forecast to develop from far southwest KS into
northwest TX, and this will occur with an increasingly low-level jet
near 50 kt at 00Z Monday. By this time, the wave is expected to take
on a negative tilt, with rapid height falls across the warm sector
and a surging cold front. The end result is likely to be severe
storms including supercells during the late afternoon from western
KS into the TX/OK Panhandles, and extending into northwest TX and
western OK prior to the cold front passage. Large hail and a few
tornadoes will be possible. As linear forcing increases with time, a
squall line producing damaging winds, including QLCS potential, is
forecast over much of OK, southern KS and northern TX. The eastward
extent of the severe threat will be limited by instability, most
likely waning roughly from the Arklatex into the Ozarks. Cooling
aloft with the shortwave trough may result in at least minimally
supportive instability into MO overnight, where wind fields will be
very strong ahead of the deepening low. Given sufficient run-to-run
model consistency, an area of 30% all-severe hazards has been added
to parts of TX, western OK and south-central KS.

On Monday/D6, the shortwave trough will move rapidly across the OH
Valley, with the surface low approaching Lower MI by 00Z Tuesday. By
this time, instability will be weaker, perhaps only a few hundred
J/kg or less. In addition, predictability is shown to decrease.
Therefore, while some severe wind threat may persist in association
with the surface low and cold front, will wait for better model
consistency before introducing a possible 15% severe risk for the
mid MS/OH Valley areas.

...Jewell.. 02/22/2023

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