SPC AC 200723

   Day 3 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0223 AM CDT Wed Sep 20 2023

   Valid 221200Z - 231200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PARTS OF THE
   CENTRAL PLAINS...

   ...SUMMARY...
   Scattered strong to severe storms, capable of all severe hazards,
   are expected across portions of the central Plains on Friday.

   ...Synopsis...
   A pronounced mid-level trough will eject into the central and
   northern Plains on Friday, supporting surface cyclogenesis across
   the central High Plains and modest low-level moisture return across
   the central Plains. Cooler mid-level temperatures will overspread
   the low-level moisture axis with the ejection of the upper trough,
   destabilizing the warm sector and increasing synoptic-scale vertical
   ascent in the process. The low-level and mid-level jets are poised
   to couple over the central Plains Friday afternoon and evening,
   supporting scattered to widespread thunderstorms, with organized
   severe potential possible.

   ...Central Plains...
   By Friday afternoon, northwestward return flow of moisture over the
   central Plains will transport at least low to mid 60s F surface
   dewpoints up to central NE, where an effective warm front will
   become established. As stronger mid-level west-southwesterly winds
   begin to overspread the warm sector, 7-8 C/km mid-level lapse rates
   should become common, contributing to around 1500 J/kg MLCAPE. Near
   the warm front, the aforementioned coupling of the low- and
   mid-level jets supports enlarged hodographs with appreciable
   curvature and some elongation. Strong deep-layer ascent should
   support supercell development during the afternoon, with large hail,
   severe gusts, and perhaps a couple of tornadoes possible (especially
   with storms that can remain discrete and anchored along the warm
   front). It is unclear how far southeast storms will initiate into
   KS, with severe potential highly dependent on the track of the
   ejecting mid-level trough and accompanying upper support. By
   evening, storms could grow upscale into an MCS from southern SD into
   NE as low-level convergence is augmented by the terminus of a
   low-level jet. Under this scenario, severe gusts would become the
   main threat.

   ...Southeast Coastline...
   A surface low is expected to meander northward along the Carolina
   coastline through Friday, resulting in scattered thunderstorms
   moving ashore. At the moment, the northeast quadrant of this cyclone
   is expected to remain just offshore (per latest guidance consensus).
   However, any westward shift in the track may support the influx of a
   higher low-level theta-e airmass, which could coincide with stronger
   low-level shear. Should this scenario become more apparent, severe
   probabilities may be introduced in future outlooks.

   ..Squitieri.. 09/20/2023

   CLICK TO GET WUUS03 PTSDY3 PRODUCT

   NOTE: THE NEXT DAY 3 OUTLOOK IS SCHEDULED BY 0730Z