SPC AC 230602

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0102 AM CDT Fri Jun 23 2023

   Valid 231200Z - 241200Z

   ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FROM FAR
   SOUTHEASTERN MONTANA AND EASTERN WYOMING SOUTHEASTWARD TO
   SOUTHWESTERN SOUTH DAKOTA AND CENTRAL NEBRASKA...

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS AN AREA
   CENTERED OVER THE TEXAS PANHANDLE...

   ...SUMMARY...
   Scattered severe thunderstorms -- capable of producing very large
   hail and strong/damaging wind gusts and a tornado or two -- are
   forecast from southeastern Montana and eastern Wyoming into
   southwestern South Dakota and central Nebraska this afternoon and
   tonight.

   ...Northern High Plains into Nebraska...
   As convection currently ongoing across the northern High Plains
   shifts northeastward across the Dakotas and Nebraska early in the
   period, daytime heating is expected to commence across the northern
   High Plains region, resulting in moderate destabilization.  As a
   short-wave trough shifts across the Intermountain West toward the
   northern High Plains, afternoon/early evening storm development is
   forecast.  With increasing mid-level southwesterlies spreading atop
   low-level easterly/southeasterly flow, initial storms will likely
   become supercells, accompanied by large hail, as well as potential
   for strong wind gusts and possibly a tornado or two.  

   Multiple clusters of storms should evolve with time, possibly
   merging into one or more larger MCSs as a 45 kt southerly low-level
   jet evolves across the central Plains.  As the convection shifts
   eastward across southern South Dakota and Nebraska, damaging wind
   gusts would likely become more widespread, along with continued hail
   potential.  At least MRGL risk may persist well into the overnight
   hours, possibly affecting the Mid Missouri Valley late in the
   period.

   ...Southern High Plains...
   Afternoon heating across the southern High Plains will contribute to
   moderate destabilization, though the boundary layer will likely
   remain capped for the most part.  By late in the day, isolated
   storms may develop from northeastern New Mexico into the Texas
   Panhandle.  Any storm which can develop would likely become
   supercellular, given 30 to 40 kt mid-level westerlies atop southerly
   flow prevailing over this region.  Given the fairly deep mixed
   layer, a couple of damaging wind gusts will be possible, along with
   potential for large hail.  

   Some CAM guidance hints at upscale growth into an MCS, spreading
   eastward either side of the Red River Valley.  As such, an eastward
   expansion of wind probabilities is being included at this time.

   ..Goss/Lyons.. 06/23/2023

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