SPC AC 041933

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0233 PM CDT Mon May 04 2026

   Valid 042000Z - 051200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF
   THE MIDWEST INTO THE OHIO VALLEY...

   ...SUMMARY...
   Scattered severe thunderstorms capable of large hail and damaging
   wind gusts are possible across portions of the Midwest this
   afternoon into tonight.  A conditional threat for severe storms with
   large to very large hail extends into portions of the
   central/southern Plains.

   ...20Z Update...
   The previous forecast remains largely on track. Only minor changes
   were made to the thunder and severe probabilities to reflect the
   latest trends in observations and high resolution model guidance.

   ..Squitieri.. 05/04/2026

   .PREV DISCUSSION... /ISSUED 1130 AM CDT Mon May 04 2026/

   ...IL into the southern Great Lakes...
   A mid-level vorticity maximum over the lower MO Valley is forecast
   to move east across IL through the late afternoon and into IN-OH
   tonight.  An associated speed maximum at 700 mb will intensify and
   overspread IL (40-50 kt) east into the southern Great Lakes while a
   pronounced strengthening of 850-mb flow (50 kt) occurs during the
   21-03z period.  Cold mid-level temperatures (-18 deg C at 500 mb)
   will act to offset initially meager moisture.  Model guidance varies
   considerably regarding moisture quality with ample spread amongst
   different model cores/PBL schemes.  However, it seems a narrow
   corridor of lower to mid 50s surface dewpoints will extend
   east-northeast from the lower MO Valley into the southern Great
   Lakes by mid to late afternoon.  Forecast soundings show weak to
   moderate buoyancy (500-1250 J/kg MLCAPE).  Morning model guidance
   shows widely scattered to scattered storms developing within the
   warm conveyor during peak heating as convective inhibition erodes. 
   Have expanded the Slight Risk farther east into this region to
   account for a hail/wind risk with the stronger storms.  Uncertainty
   remains regarding quality of boundary-layer moisture across the
   northern third of IN into northwest OH where hodographs become
   enlarged later this afternoon into the early evening.  Will
   re-evaluate the tornado risk for the 20 UTC outlook if in fact
   moisture quality seems sufficient for a focused, short-duration
   tornado risk across the aforementioned corridor. 

   ...Eastern KS into the Mid MS Valley...
   Thunderstorm development is anticipated during the afternoon along a
   cold forecast to extend through southern WI and
   eastern/southern IA. Thunderstorms along the front will initially be
   displaced north of the better shear and buoyancy, so somewhat
   transient updraft structures and/or frontal undercutting will likely
   limit storm severity. Even so, high cloud bases and a deeply mixed
   boundary layer could result in a few strong gusts.  Later in the
   evening, more storm development appears likely on the front as it
   moves into eastern KS and northern/central MO. Here, stronger shear
   and buoyancy should support more robust updrafts and a relatively
   higher probability for severe storms. Large to very large hail is
   the primary risk.  

   ...Central Kansas into Oklahoma and northern Texas...
   A dryline will extend from central KS south-southwestward into
   northwest TX by mid afternoon as a surface low evolves near the TX
   Panhandle/OK/KS border region.  Strong diurnal heating will likely
   erode most convective inhibition by the early evening, while steep
   lapse rates contribute to moderate buoyancy along the dryline.
   Isolated thunderstorms are possible on the dryline from central KS
   into northwest TX during the 22-02 UTC period.  Veering and
   strengthening flow with height beneath 100-kt westerly 200-mb flow
   will support supercells.  Isolated large to very large hail will be
   the primary risk with the stronger storms, although severe gusts are
   also possible.

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