SPC AC 231623

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1123 AM CDT Tue Apr 23 2024

   Valid 231630Z - 241200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR NORTHWEST
   TEXAS...

   ...SUMMARY...
   Isolated severe thunderstorms capable of producing large hail
   (potentially 2+ inch diameter) and gusts to 65 mph will be possible
   this afternoon and evening across northwest Texas.

   ...Northwest TX...
   Visible satellite imagery and surface analysis this morning indicate
   the initial stage of moisture return is occurring across the
   southern Great Plains in the wake of a frontal intrusion into the
   Gulf a few days ago.  A mid-level ridge will increasingly become
   established across the central/southern Rockies and adjacent High
   Plains as a Great Lakes disturbance gradually becomes more displaced
   from the region.  An associated cold front will move southward
   across KS/OK before eventually stalling tonight across southeast OK
   and northwest TX.  Weak lee cyclogenesis will aid in maintaining a
   southerly low-level fetch across central into west TX as strong
   heating results in a sharpening dryline by late afternoon.  Isolated
   thunderstorm development will be most probable near the triple point
   20-22Z.  Steep lapse rates coupled with adequate moisture (1500-2000
   J/kg MLCAPE) and veering flow beneath moderate westerlies, will
   support an initial supercell mode.  Isolated very large hail of
   2-2.5 inches in diameter will be the main threat, along with a few
   55-65 mph gusts.

   ...Northern IL/southeast WI/Lower MI late this afternoon/evening...
   Have not changed the existing outlook for this region due primarily
   to consistency in model data and the forecast conceptual model not
   deviating.  Water-vapor imagery this morning shows a mid-level
   trough over the Upper Midwest and this will continue southeast into
   the central Great Lakes by mid evening.  An associated surface
   trough will likewise move southeastward, and this trough will be
   preceded by a band of rain with minimal buoyancy.  Behind the rain
   band, surface heating with steepening low-level lapse rates and
   cooling midlevel temperatures will support weak surface-based
   buoyancy just ahead of a secondary frontal surge.  Some low-topped
   convection will be possible late this afternoon through late evening
   from northern IL/southeast WI into Lower MI.  The stronger storms
   could yield a localized marginal hail/damaging wind threat.

   ..Smith/Moore.. 04/23/2024

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