SPC AC 091334

   Day 1 Convective Outlook RESENT 1
   NWS Storm Prediction Center Norman OK
   0834 AM CDT Thu May 09 2019

   Valid 091300Z - 101200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THROUGH THIS
   EVENING FROM MS TO SOUTH TX...

   ...SUMMARY...
   Scattered severe thunderstorms are expected from Mississippi and
   Louisiana to south Texas through this evening.  Damaging winds and
   large hail will be the main threats.

   ...MS to south TX through this evening...
   Overnight warm advection thunderstorms across LA/MS have gradually
   merged into more of a QLCS which will move east-southeastward
   through the day across LA/MS/AL.  Tropical moisture is present to
   the south of the QLCS from TX to MS, and the steeper midlevel lapse
   rates are confined to areas farther west across TX.  MLCAPE today
   will range from 2000 J/kg across southern MS to greater than 4000
   J/kg across south TX.  Low-level flow/shear is favorable for
   right-moving supercells this morning across LA/MS in the warm
   advection zone.  However, low-level flow will weaken through midday
   (as confirmed by the VWP at POE since 09z) as an associated
   mid-upper speed max translates northeastward from AR toward the OH
   Valley.  Low-level flow will remain weak to the west in TX, but
   effective bulk shear will be sufficient for supercells (as well as
   splitting storms across south TX).

   The convective mode will remain predominantly linear across MS
   today, with a gradual transition to anafrontal convection across LA
   atop the reinforced cold pool.  The eastern extent of the severe
   threat will be limited by more marginal buoyancy farther to the east
   across AL.  Farther west, weakening convective inhibition in the
   warm sector and a cold front moving slowly southward will help focus
   thunderstorm development this afternoon in TX, and storms may also
   form over the higher terrain in Mexico and cross the Rio Grande. 
   Given the potential for some supercell structures in an environment
   with strong buoyancy and steep midlevel lapse rates, isolated very
   large hail will be possible in TX.  Otherwise, damaging gusts and
   perhaps a brief tornado or two can be expected through this evening.

   ...TN to the OH Valley today...
   From TN into the OH Valley, buoyancy will be limited (MLCAPE
   500-1000 J/kg) by clouds slowing surface heating, mediocre midlevel
   lapse rates, and rather modest low-level moisture north of the
   widespread convection across LA/MS.  Likewise, vertical shear will
   not be particularly strong within the warm sector.  Isolated
   strong/damaging gusts will be the main concern.

   ..Thompson/Smith.. 05/09/2019

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