SPC AC 211736

   Day 2 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1236 PM CDT Sun Jun 21 2020

   Valid 221200Z - 231200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER A PORTION OF
   THE SOUTHERN PLAINS INTO THE LOWER TO MIDDLE MISSISSIPPI VALLEY
   REGION...

   ...SUMMARY...
   Strong to severe thunderstorms are possible Monday from a portion of
   the southern Plains into the lower to middle Mississippi Valley
   regions. Other strong storms are possible over the Midwest and the
   Middle Atlantic area.

   ...Southern Plains into the lower to middle Mississippi Valley...

   Synoptic upper pattern will remain dominated by an upper trough
   situated from the central and northern Plains through the Midwest
   and Great Lakes. This feature will continue slowly east through
   Monday. A cold front will likely extend from a weak surface low in
   IA southwest through KS into the TX and OK Panhandles. A dryline
   will persist across west and southwest TX. Farther north another
   cold front should extend from northwest WI southwest and west into
   SD.

   An MCS will likely be ongoing at the start of this period most
   likely from a portion central or eastern OK and possibly AR. Some
   threat for damaging wind and hail could persist with this activity
   as it advances southeast during the morning before weakening. These
   storms will leave an outflow boundary somewhere from southern OK
   into northern TX. Redevelopment along this boundary during the
   afternoon is possible, but is uncertain given potential subsidence
   in wake of a shortwave trough and possible capping issues.
   Nevertheless, the atmosphere will likely become moderately to
   strongly unstable (2000-3500 J/kg MLCAPE) in pre-frontal warm sector
   across OK into northern TX supported by steep lapse rates, mid to
   upper 60s F dewpoints and diabatic heating of the surface layer.
   Storms could develop in 3 separate regimes including the evolving
   upslope region across eastern NM into western TX, along the cold
   front from southern KS, southwest MO and northern OK or along the
   old outflow boundary across northern TX. Vertical wind profiles with
   modest (30-35 kt) vertical shear will generally support multicells
   and possibly some supercell structures, but there may be a tendency
   for storms to congeal into lines and clusters as they develop
   southeast. Damaging wind and large hail will be the main threats
   from late afternoon into the evening. An upgrade to enhanced might
   be required over a portion of this region once mesoscale details
   become more clear.
    
   ...Midwest...

   Recovery is expected in wake of decaying morning MCS, and the
   atmosphere will likely become moderately unstable in pre-frontal
   warm sector. Storms will likely once again develop along and ahead
   of the front and in association with a migratory shortwave trough.
   While vertical wind profiles will remain modest and generally
   supportive of multicells, a few storms could produce locally strong
   wind gusts and hail.

   ...Middle Atlantic region...

   Thunderstorms will once again develop in association with a
   prominent northeast-progressing vorticity maximum. The atmosphere in
   this region will become moderately unstable, and though weak
   vertical shear will promote pulse/multicells, a few instances of
   downburst winds and hail will be possible during the afternoon.

   ..Dial.. 06/21/2020

   CLICK TO GET WUUS02 PTSDY2 PRODUCT

   NOTE: THE NEXT DAY 2 OUTLOOK IS SCHEDULED BY 0600Z