SPC AC 240538

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1238 AM CDT Wed Apr 24 2024

   Valid 241200Z - 251200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF
   WEST TEXAS THIS EVENING...

   ...SUMMARY...
   Strong to severe thunderstorms will be possible today across parts
   of Oklahoma and west Texas. Large hail and severe gusts will be the
   primary hazards.

   ...Synopsis...

   An upper ridge over the Rockies will shift east into the Plains
   through tonight. However, guidance suggests subtle shortwave
   impulses will migrate through the ridge during the late afternoon
   into the evening/overnight. At the surface, strengthening lee
   troughing is forecast across eastern NM near the TX border.
   Meanwhile, a stationary boundary is forecast to extend across the TX
   South Plains vicinity into southern/central OK, while a dryline
   extends southward along the NM/TX border into southwest TX. Several
   forecast models suggest a bulge in the dryline is possible across
   far west TX where a weak surface low may develop. Overnight, the
   stationary boundary is expected to lift northward as a warm front,
   becoming located across the TX Panhandle into northern OK.

   Further east, an upper trough will move across the Northeast states.
   Boundary-layer moisture will remain limited, though midlevel
   moisture will be plentiful. Cool temperatures aloft and modest
   westerly flow will support isolated to scattered thunderstorms ahead
   of an eastward-progressing cold front.

   ...OK - This Morning...

   Thunderstorms are expected to develop early this morning across
   central OK north of the stationary boundary in a warm advection
   regime along the north edge of returning low-level moisture. This
   activity is expected to be elevated. However, steep midlevel lapse
   rates and increasing westerly mid/upper flow should be sufficient
   for organized cells. Large hail will be possible with storms that
   develop. However, coverage remains in question given expected height
   rises through the morning hours as the upper ridge slowly shifts
   east.

   ...West TX toward SW OK - This evening...

   Capping will preclude convection for most of the day. However,
   low-level moisture will increase with northwest extent on
   southeasterly low-level flow, and low 60s F dewpoints are expected
   into the Permian Basin and South Plains vicinity. Steep midlevel
   lapse rates atop this moistening boundary-layer will foster moderate
   instability from 1500-2500 J/kg. By late afternoon/early evening,
   convection should begin to develop as inhibition weakens due to
   increasing moisture and some indication of a weak impulse ejecting
   east across the southern Rockies. Veering low-level wind profiles
   become west/southwesterly aloft will result in favorable shear
   profiles supporting supercells. Large hail to 2 inches in diameter
   and gusts to 70 mph will be possible with storms that develop. 

   ...Northern OK - Late Tonight...

   As the stationary boundary lifts northward as a warm front
   overnight, another round of warm advection thunderstorms will be
   possible, this time from the eastern TX Panhandle into northern OK.
   Forecast guidance varies considerably regarding coverage and
   location of potential development, though the overall environment
   (moderate elevated instability and modest shear) conditionally will
   support hail.

   ...Northeast...

   While boundary-layer moisture will remain poor today, cold
   temperatures aloft will support weak instability. Deep-layer
   westerly flow around 20-30 kt may support transient organized
   cells/clusters by early afternoon. Meanwhile, heating ahead of the
   cold front will allow for steepening low-level lapse rates. Gusty
   winds to 40 mph will be possible with afternoon thunderstorms, but
   overall severe potential appears too low for severe probabilities.

   ..Leitman/Weinman.. 04/24/2024

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