New SPC Update:
View attachment 124266
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1021 AM CST Tue Nov 29 2022
Valid 291630Z - 301200Z
...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON
AND TONIGHT OVER PARTS OF NORTHEAST LOUISIANA...EXTREME SOUTHEAST
ARKANSAS...CENTRAL AND NORTHERN MISSISSIPPI...AND NORTHWEST
ALABAMA...
...SUMMARY...
Strong tornadoes, very large hail, and severe wind gusts are
forecast this afternoon into the overnight period across parts of
the lower to mid Mississippi Valley, Mid-South and parts of the
Southeast.
...Regional Outbreak of severe thunderstorms and tornadoes is
forecast today and tonight for parts of the lower Mississippi
Valley...
...Lower MS Valley...
Morning water vapor imagery shows a broad upper trough over much of
the CONUS this morning, with several fast moving shortwave troughs
moving across the southwest into the southern Plains. Strong
southerly low-level winds have developed across the lower MS Valley,
aiding in the rapid return of rich Gulf moisture. Dewpoints in the
mid/upper 60s have spread into much of east TX and LA, and should
extend into central MS by mid-afternoon. Plentiful low clouds are
present, limiting daytime heating. But relatively steep mid-level
lapse rates and returning moisture will lead to widespread MLCAPE
values of 1000-1500 J/kg later today, with only a weak cap.
Vertical shear profiles are very strong throughout the region, with
effective SRH values of 200-400 m2/s2 beneath 50+ knots of
deep-layer shear. Given the subtle forcing today, relatively
long-lived discrete supercell storms are expected with an attendant
threat of intense and long-track tornadoes.
Present indications are that primary thunderstorm development will
begin early this afternoon over parts of LA, spreading quickly into
MS. This corridor may see multiple waves of severe convection as
storms redevelop upstream through the evening. Along with the
strong tornado threat, very large hail and damaging wind gusts may
occur with these storms.
Consideration was made to introduce a
small HIGH risk,
but still too much uncertainty in the exact
corridor of highest risk since moisture is not yet in place and
there is no surface boundary to focus on.
..Hart/Wendt.. 11/29/2022
