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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