SPC AC 111956

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0256 PM CDT Fri Jun 11 2021

   Valid 112000Z - 121200Z

   ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS EASTERN
   KS...NORTHEAST OK...FAR WESTERN MO...

   ...SUMMARY...
   Scattered severe thunderstorms (some of which may be significant)
   with damaging winds as the primary hazard, along with large hail,
   are expected through this evening. The most likely corridor is
   across eastern Kansas and adjacent western Missouri through parts of
   north-central and northeast Oklahoma.

   ...20Z Update...

   ...Lower MO Valley to the Ozarks...
   Current trends with the ongoing organized convective system across
   the Lower MO Valley suggest the potential for strong wind gusts will
   likely extend into more of west-central MO, with the corridor of
   weak surface winds from DMO through TBN acting as an the eastern
   bound. Portions of the line along and just east of the KS/MO border
   have begun to surge southward (recent observation at STJ reported 55
   kt) and the air mass downstream remains strongly unstable and
   moderately sheared.

   ...Upper MS Valley and WI....
   Only changes over this area was to trim up wind probabilities based
   on current trends. Additional thunderstorm activity remains possible
   tonight, with an associated threat for isolated hail.

   ..Mosier.. 06/11/2021

   .PREV DISCUSSION... /ISSUED 1109 AM CDT Fri Jun 11 2021/

   ...Lower MO Valley to the Ozarks and OK...
   An MCS near the NE/IA/MO/KS border is expected to persist south
   across much of eastern KS and far western MO this afternoon into
   north-central and northeast OK by evening, around the eastern
   periphery of a mid-level ridge over the southern High Plains. For
   near-term forecast information, please see MCD 922. 

   Though vertical shear will remain rather modest, there could be
   mesoscale enhancement due to MCV formation within the MCS as it
   develops southward through the afternoon. Large to extreme buoyancy
   with MLCAPE of 3000-5000 J/kg is expected in advance of the
   convective cluster, owing to robust heating of a very moist boundary
   layer (mid 70s dew points), beneath steep mid-level lapse rates.
   These thermodynamic profiles will favor intense updrafts along the
   southwest flank of the cluster where transient supercell structures
   will be capable of large hail. The overall primary threat should be
   damaging winds with a series of downbursts given heavy precipitation
   loading. The cluster/MCS is expected to move across eastern KS
   during peak heating with the largest buoyancy and steepest low-level
   lapse rates, when the severe wind and large hail threat should be
   greatest. Some severe threat will likely persist across at least
   northern OK through this evening, where lift along the front/outflow
   and residual large CAPE should support additional storm development
   to the south and southwest.

   ...Upper MS Valley and WI...
   Outflow associated with pre-frontal convection is moving eastward
   across northwest WI and southeast MN, while a separate/weak
   baroclinic zone oriented will also persist from northwest to
   east-central WI. These boundaries should help focus thunderstorm
   development this afternoon. Despite modest vertical shear, moderate
   buoyancy (MLCAPE of 1000-2000 J/kg) will favor storms with isolated
   damaging downbursts and marginally severe hail through about sunset.

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   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 0100Z