Subj : DAY48SVR: Nws Storm Prediction Center Norman Ok
To   : wx-storm@lists.illinois.edu
From : COD Weather Processor
Date : Wed Mar 29 2023 08:51:40

ACUS48 KWNS 290851
SWOD48
SPC AC 290850

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0350 AM CDT Wed Mar 29 2023

Valid 011200Z - 061200Z

....DISCUSSION...
Some severe potential could continue into Day 4/Sat associated with
ongoing convection at the beginning of the period. Showers and
thunderstorms will likely be ongoing across portions of the
Appalachians as a cold front shifts east across the Mid-Atlantic and
Southeast. While a seasonally moist airmass will be in place amid
strong deep-layer southwesterly flow, widespread precipitation and
cloud cover will likely temper destabilization before convection
moves offshore by late afternoon.

On Day 5/Sun, forecast guidance generally indicates a more
zonal/low-amplitude pattern across much of the CONUS. However, a
weak shortwave impulse may migrate across parts of the southern
Plains and Lower MS Valley. Medium range guidance varies in the
timing and intensity of this feature considerably, and confidence is
too low to delineate severe probabilities at this time.

Heading into early next week, severe potential will increase once
again for portions of the central/south-central U.S. vicinity. A
large-scale upper trough will dig south and east across the western
states on Day 6/Mon. Timing differences are apparent in medium range
guidance, but stronger southwesterly deep-layer flow should approach
the southern Plains by late Mon/early Tue. As this occurs, intense
surface cyclogenesis is forecast to occur over the central High
Plains overnight. The ensuing mass response will spread Gulf
moisture northward across the south-central states toward the lower
MO Valley by Day 7/Tue morning. A conditional severe threat could
develop over portions of the central/southern Plains Day 6/Mon
night, but confidence is too low to delineate a 15 percent severe
area at this time. However, on Tuesday, as the upper trough ejects
east and spreads intense deep-layer southwesterly flow over the
Lower/Mid-MS Valley to the Ohio Valley, a sharp cold front will
surge east. Rich gulf moisture across a broad warm sector will
supply plenty of instability, and potentially widespread severe
thunderstorms will once again be possible across the Mid-MS/Lower OH
Valley toward the Mid-South and TN Valley.

Some severe potential could continue into Day 8/Wed across parts of
the Mid-Atlantic as the surface cold front continues to surge east.
Severe potential will be somewhat dependent on how far east
convection evolves in Day 7/Tue and impacts on boundary-layer
destabilization into Day 8/Wed. However, confidence is too low to
include probabilities at this time.

...Leitman.. 03/29/2023

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