SPC AC 121226

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0726 AM CDT Sun Jun 12 2022

   Valid 121300Z - 131200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PORTIONS OF A
   LARGE AREA FROM THE NORTHERN AND CENTRAL PLAINS INTO THE OHIO VALLEY
   AND MID ATLANTIC REGION...

   ...SUMMARY...
   Isolated to scattered strong/severe thunderstorms are expected
   across the northern and central Plains, with large hail and damaging
   winds the main threats. A few tornadoes could occur across the
   northern High Plains region. Isolated severe may also be noted
   across the lower Ohio Valley and parts of the southern middle
   Atlantic. Wind and hail are the primary threats.

   ...Plains...
   Only minor changes have been made to the ongoing forecast. Despite
   the axis of a broad upper ridge extending from NM into CO/WY,
   considerable mid-level moisture is evident in water vapor imagery
   along this corridor.  Large scale forcing will be weak over the
   central/northern Rockies, but model guidance is in strong agreement
   that scattered afternoon thunderstorms will develop from northeast
   CO into eastern WY/MT.  These storms will build eastward during the
   evening into the Dakotas/NE/KS.  Supercell storm structures are
   expected, capable of very large hail and damaging winds.  A few
   tornadoes are possible as well.  Storms may persist the longest over
   the northern Plains, with activity spreading into western MN
   overnight.

   ...OH Valley to Mid-Atlantic...
   Latest surface analysis shows a weak warm front extending from
   northeast MO into parts of IL/IN/OH. Dewpoints along and south of
   the boundary range from the 50s over OH to the 70s over MO.  Pockets
   of daytime heating along this corridor, coupled with moderately
   steep mid-level lapse rates, will yield afternoon MLCAPE values of
   1000-1500 J/kg.  This will likely be sufficient for a few
   thunderstorms to develop and track rather quickly eastward. While
   confidence in the details of the convective evolution are low, there
   are two areas where the risk seems high enough to maintain SLGT
   risk.

   The first area of concern is over portions of VA/NC.  A relatively
   moist and potentially unstable air mass is present today in this
   region.  Morning clouds are expected to give way to afternoon
   heating/destabilization and the development of at least isolated
   thunderstorms.  Forecast soundings suggest sufficient deep-layer
   shear for convective organization and perhaps a supercell or two. 
   Locally damaging winds are the main threat through the early
   evening.

   Another area of concern is over parts of MO/IL/IN/KY.  Hot and humid
   conditions will result in a very unstable air mass with afternoon
   MLCAPE values of 3000-4000 J/kg, but a capping inversion limits
   confidence in convective initiation.  Winds aloft are favorable in
   this region for rotating and bowing structures capable of large hail
   and damaging winds.  Model guidance varies considerably regarding
   the timing and placement of storms today and tonight, but given the
   conditional risk, will maintain the ongoing SLGT risk with few
   changes.

   ...KS/MO/AR/TN...
   A cluster of thunderstorms had developed in the pre-dawn hours over
   parts of NE.  This activity is poorly handled in the model guidance.
    Given the favorable downstream air mass and rapid expansion on IR
   satellite imagery, there is some concern that this cluster will
   persist and track across northeast KS into MO.  Therefore have
   expanded the SLGT risk to areas ahead of the storms.  Please see MCD
   #1127 for further details.  Forecast soundings suggest a risk of
   damaging wind gusts and hail.

   ..Hart/Broyles.. 06/12/2022

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