SPC AC 090059
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0659 PM CST Wed Feb 08 2023
Valid 090100Z - 091200Z
...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FOR PARTS OF
CENTRAL/SOUTHERN MS AND EXTREME NORTHEAST LA...
...SUMMARY...
Severe thunderstorms remain possible tonight, mainly across parts of
the lower into middle Mississippi Valley. A few tornadoes and
scattered damaging winds will be possible.
...Lower/Mid MS Valley...
Some tornado threat remains evident tonight across the lower/mid MS
Valley region, though widespread thunderstorm development prior to
the arrival of favorable wind profiles has resulted in a complicated
convective evolution that will continue through the evening.
Lower/mid 60s F dewpoints have spread as far north as eastern
AR/western TN, in advance of a deepening surface cyclone near the
OK/AR border. Seasonably strong diurnal heating earlier today has
resulted in MLCAPE increasing above 1000 J/kg in areas where
convective overturning has yet to occur. As the primary
mid/upper-level trough takes on an increasingly negative tilt and
ejects across the Ozarks into the mid MS Valley tonight, deep-layer
flow/shear will increase substantially across the warm sector of the
deepening cyclone, with low-level shear/SRH becoming favorable for
tornado development.
The presence of ongoing widespread thunderstorms and the likelihood
of a mixed convective mode cast some uncertainty on the magnitude of
the tornado threat tonight. Embedded supercells will remain possible
within a pre-frontal thunderstorm cluster moving out of northeast LA
into southern/central MS, with a threat of locally damaging gusts
and a few tornadoes. Farther west, widespread convection immediately
ahead of the cold front may evolve into a loosely organized QLCS,
with damaging gusts and line-embedded tornadoes possible. With 0-1
km SRH expected to increase into the 250-400 m2/s2 range after 02Z,
any surface-based supercell that can be sustained into mid/late
evening will pose a conditional risk of a strong tornado, though
this scenario remains uncertain. Otherwise, damaging gusts and a
couple of tornadoes will be possible as widespread thunderstorms
move across much of MS into southwest TN, before a weakening trend
commences overnight as convection outpaces the more favorable
low-level moisture return and destabilization.
...Midwest into the lower OH Valley...
Increasingly low-topped convection will move northeastward into
parts of the Midwest and OH Valley overnight, in conjunction with
the deepening surface low. While lightning activity may diminish
with time as instability becomes increasingly scant, very strong
low-level flow (60+ kt at around 1 km AGL) may support the potential
for isolated convectively enhanced gusts capable of producing wind
damage through the end of the period.
..Dean.. 02/09/2023
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