SPC AC 231735

   Day 2 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1235 PM CDT Sat May 23 2020

   Valid 241200Z - 251200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE MIDDLE
   MISSOURI VALLEY INTO PORTIONS OF THE CENTRAL AND SOUTHERN PLAINS...

   ...SUMMARY...
   Severe thunderstorms are possible across portions of the central
   Plains, Middle Missouri Valley, and southern High Plains on Sunday.
   Large hail and damaging wind gusts are the primary severe threats.

   ...Synopsis...

   An upper level trough centered over the Rockies Sunday morning will
   shift eastward toward the Plains by Monday morning. Several
   shortwave impulses are forecast to eject northeastward ahead of the
   main trough, influencing convection from the southern High Plains
   toward the mid-Missouri and upper-Mississippi Valley regions.
   Overall, deep layer flow will not be particularly strong, but a belt
   of 35-45 kt 700 mb flow will spread across portions of the
   southern/central Plains to the Upper Midwest amidst weak height
   falls. 

   At the surface, a broad warm sector will exist to the east of a
   dryline from western OK/TX, and ahead of a cold front from eastern
   portions of the central Plains toward the Upper Midwest. Forecast
   guidance varies greatly with regards to ongoing convection Sunday
   morning -- some have it, some do not, and none forecast it in the
   same place. There is also inconsistency in how much airmass recovery
   will occur in areas that are affected by outflow from convection on
   Saturday into early Sunday morning. As a result, considerable
   uncertainty remains for Sunday severe potential and a broad Slight
   risk is generally maintained with only minor changes from the
   previous outlook. 

   ...Central Plains to Upper Midwest...

   Strong heating of a very moist airmass with surface dewpoints in the
   mid to upper 60s will result in strong destabilization during the
   afternoon. A plume of steep midlevel lapse rates will exist across
   the region, and MLCAPE as high as 2500-3500 J/kg is forecast in
   areas unaffected by morning convection. Instability will be somewhat
   less further north across southern MN into central WI where
   dewpoints will be lower, but still sufficient for strong to severe
   storms. Convection will develop ahead of an eastward advancing cold
   front during the afternoon. Shear will be marginal, but adequate,
   for supercells. Long, straight hodographs amidst steep lapse rates
   suggest mainly potential for large hail. Given weak shear, any
   initially discrete convection should trend toward clusters with
   possibly some bowing segments developing through mergers/outflow
   interactions.

   ...Southern Plains...

   The surface cold front will be located from central NE into western
   KS and southeast CO Sunday morning. Post-frontal upslope flow will
   allow high-based convection to develop near the higher terrain in
   CO. As this convection moves east into the southern High Plains,
   weak elevated instability and very steep midlevel lapse rates should
   be sufficient in the presence of strong effective shear to support a
   couple of severe storms capable of large hail. Additional storms are
   expected to develop near a triple point near southwest KS and
   southward along the dryline. Surface dewpoints in the mid 60s to
   near 70 F and strong heating into the 80s will result in strong
   destabilization and supercells are expected. Large hail and damaging
   gusts will be the main concern. Convection is expected to quickly
   transition toward bowing/linear segments as a low level jet
   increases and frontal forcing increases. One of more bowing segments
   could track eastward across western/central KS into western OK and
   central/southern TX during the evening hours. Given aforementioned
   uncertainties, how far east severe convection persists remains
   uncertain.

   ...Eastern TX/western LA...

   Strong instability will be in place across the region as warm
   advection spreads northward ahead of the Rockies/Plains upper
   trough. Most guidance indicates an MCV migrating across the region,
   which could lead to enhancement of low/mid level shear. As a result,
   a few intense cells are expected and could producing strong, locally
   damaging downburst winds.

   ..Leitman.. 05/23/2020

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