SPC AC 210732

   Day 3 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0232 AM CDT Tue May 21 2024

   Valid 231200Z - 241200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM PARTS OF
   OKLAHOMA AND KANSAS INTO THE ARKLATEX VICINITY...

   ...SUMMARY...
   Severe thunderstorms are possible across portions Kansas and
   Oklahoma into the Arklatex region on Thursday. Damaging gusts, hail
   and a couple of tornadoes will be possible. Isolated strong to
   severe thunderstorms also will be possible across the central Plains
   into South Dakota, and across the Mid-Atlantic and Northeast coastal
   areas.

   ...Mid-Atlantic and Northeast...

   Broad, low-amplitude southwesterly flow will persist across much of
   the eastern CONUS on Thursday. Some enhancement of mid/upper flow is
   forecast across from the Northeast states as a compact upper
   shortwave trough glances the international border. At the surface, a
   cold front will move east across the Northeast. This will focus
   thunderstorm activity during the afternoon from VA northeast along
   the Atlantic coastal vicinity amid a seasonally moist airmass. 

   Modest destabilization and steepening low-level lapse rates are
   forecast. Strong gusts will be possible with thunderstorms during
   the late morning into the afternoon. A plume of modest midlevel
   lapse rate also will overspread the region, and vertical shear will
   be sufficient, especially from NJ northward, to support sporadic
   marginal hail as well.

   ...Plains Vicinity...

   A subtle upper shortwave trough is forecast to migrate across the
   southern Plains and Mid-South vicinity, while another deepening
   shortwave trough overspreads the northern/central Plains. Both of
   these features will result in increasing mid/upper southwesterly
   flow (30-50 kt) on Thursday. 

   At the surface, lee cyclogenesis is forecast over the central High
   Plains. A surface low will progress east across SD/NE to IA/MN, with
   a cold front developing east/southeast across the northern/central
   Plains during the evening/overnight. Meanwhile, a dryline will
   extend southward from a secondary low over western KS into central
   TX. Strengthening low-level southerly flow in response to the
   deepening low will transport Gulf moisture northward ahead of the
   front, with near-60 F dewpoints as far north as NE. Richer
   boundary-layer moisture (mid 60s to low 70s F) will remain farther
   south.

   Strong destabilization ahead of the dryline and increasing
   large-scale ascent will support thunderstorm development during the
   afternoon across the southern Plains vicinity. One or more clusters
   will track southeast through the evening into the ArkLaTex region.
   All severe hazards appear possible. Severe potential may be less
   with northward extent into NE/SD and vicinity given more modest
   moisture, but at least isolated strong/severe storms appear possible
   given an otherwise favorable environment.

   ..Leitman.. 05/21/2024

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