SPC AC 241937

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0237 PM CDT Wed Apr 24 2024

   Valid 242000Z - 251200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE TEXAS
   SOUTH PLAINS INTO THE PERMIAN BASIN...

   ...SUMMARY...
   Isolated large hail and severe gusts will be possible this evening
   from the Texas South Plains into the Permian Basin.

   ...20Z Update...

   ...TX South Plains into Permian Basin...
   Forecast outlined in the previous discussion (appended below)
   remains valid. Isolated thunderstorms still appear possible within
   the destabilizing air mass from the TX South Plains into the Permian
   Basin. Moderate buoyancy (i.e. MLCAPE from 2000 to 2500 J/kg) and
   vertical shear (i.e. 0-6 km bulk shear from 40-50 kt) support the
   potential for supercells within any sustained/mature convection.
   Primary risk with any supercells would be large to very large hail
   up to 2.5" in diameter and strong gusts up 70 mph. Tornado risk
   still appears low, although non-zero given the increasing low-level
   moisture and shear expected this evening.

   ...OK into Central/Eastern KS...
   Thunderstorms are expected to develop tonight from central OK into
   central and eastern KS as warm-air advection increases throughout
   the warm sector. A few stronger storms capable of marginally severe
   hail around 1" in diameter are possible through Thursday morning.

   ..Mosier.. 04/24/2024

   .PREV DISCUSSION... /ISSUED 1120 AM CDT Wed Apr 24 2024/

   ...West central TX this evening...
   Water-vapor imagery this morning shows a midlevel low/shortwave
   trough west of the southern CA/Baja California coasts and it will
   move into the lower CO Valley by tomorrow morning.  A mid-level
   ridge situated over the southern Rockies will gradually move east
   over the southern High Plains today.  A lee trough will become more
   pronounced throughout the day and act to maintain southerly
   low-level flow across much of TX south of a warm front.  The warm
   front initially analyzed this morning near the Red River will slowly
   move northward.  Late morning surface observations over the Permian
   Basin/Concho Valley indicate low to mid 60s dewpoints.  The 12z MAF
   raob showed a 7.9 deg C/km 700-500 mb lapse rate, indicative of an
   elevated mixed layer.  

   Weak forcing for ascent at best is expected beneath the mid-level
   shortwave ridge, thereby limiting potential storm coverage.  Despite
   the associated forcing/capping concerns, convective inhibition will
   erode considerably by 21-00z.  Uncertainty remains regarding storm
   development, but additional heating this afternoon --perhaps delayed
   a bit due to considerable low cloud cover-- will result in moderate
   buoyancy (2000-2500 J/kg MLCAPE).  Relatively weak but veering winds
   in the low levels beneath 65-kt westerly 250-mb flow will support a
   conditional threat for supercells.  Deeper mixing over the Permian
   Basin may be enough to overcome and lead to a couple of storms by
   late afternoon/early evening along the dryline.  Isolated very large
   hail up to 2.5 inches in diameter and severe outflow gusts of 60-70
   mph are possible.  There will be an increase in low-level shear this
   evening and low-level moisture will be greater compared to
   yesterday, so an isolated tornado will also be possible in a narrow
   time window this evening before inhibition increases and storms
   weaken.

   ...OK into KS through tonight...
   Elevated thunderstorms near the OK/KS border late this morning are
   likely the result of low-midlevel warm advection and weak buoyancy
   rooted near 700 mb.  Some of this convection could persist this
   afternoon but it is uncertain whether intensification will occur
   with this activity and whether a marginal hail threat develops.  The
   more probable risk for elevated storms will occur tonight coincident
   with strengthening warm advection and increasing low-level moisture.

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