SPC AC 121254

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0754 AM CDT Wed Mar 12 2025

   Valid 121300Z - 131200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PARTS OF NORTH
   AND NORTHEAST TEXAS AND SOUTHEAST OKLAHOMA INTO SOUTHWEST ARKANSAS
   AND NORTHWEST LOUISIANA...

   ...SUMMARY...
   Scattered severe thunderstorms are possible from north Texas and
   southeast Oklahoma into the Ark-La-Tex late this afternoon and
   evening.  Large to very large hail and severe gusts are the primary
   hazards.

   ...Synopsis...
   Water-vapor imagery this morning shows a potent mid-level shortwave
   trough over NM/Chihuahua quickly moving eastward into Far West and
   Southwest TX.  This disturbance will reach the lower MS Valley and
   central Gulf Coast by early Thursday morning.  A belt of strong
   west-southwesterly 500-mb flow will move through the base of the
   trough over TX into the lower MS Valley during the period.  In
   response, a surface low will develop across western Texas and
   Oklahoma with increasing southerly flow and moisture return across
   Texas into Oklahoma and into the lower Mississippi Valley ahead of
   the dryline/front.

   ...Parts of TX/OK eastward into the Lower MS Valley...
   Surface analysis shows a plume of northward-moving moisture from a
   modifying Gulf airmass across TX near and to the east of I-35 this
   morning.  An initially strong cap (reference 12 UTC Fort Worth, TX
   raob) will inhibit storm development through the mid afternoon as
   southerly low-level moisture continues to stream northward into
   northeast TX and eastern OK/western AR.  Moderate instability is
   forecast by mid-late afternoon due in part to cold-air advection in
   the mid-levels associated with the approaching trough.  Upwards of
   1000-1500 J/kg MLCAPE is forecast east of the dryline.  Strong
   heating will likely lead to surface dewpoints mixing into the
   mid-upper 50s over north and northeast TX.  Model guidance indicates
   scattered storms will likely develop once the cap erodes in parts of
   eastern OK southward into TX with this activity spreading east into
   adjacent portions of AR/LA this evening and eventually into the
   Ark-La-Miss late.  Lower coverage of storms is forecast farther
   south across east-central into parts of east TX.  However, stronger
   deep-layer shear with southward extent will favor supercell modes
   compared to a mix of strong/severe multicells and supercell
   structures farther north.  Large to very large hail (potentially 2-3
   inches in diameter) is possible with the stronger storms.  An
   attendant wind risk will also accompany the stronger storms given
   the steep lapse rates.  Upscale growth into one or two clusters is
   possible during the evening as this activity moves east into the
   lower MS Valley.  

   ...Elsewhere...
   Short-term model guidance indicates a very low-topped forced band
   will move southeast across parts of the southern CA coast in advance
   of an approaching eastern Pacific mid-level trough.  A strong gust
   cannot be ruled out with this activity, but the risk appears too
   marginal for low-severe probabilities.

   ..Smith/Dean.. 03/12/2025

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