SPC AC 132031

   Day 1 Convective Outlook CORR 2
   NWS Storm Prediction Center Norman OK
   0331 PM CDT Fri May 13 2022

   Valid 132000Z - 141200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS CENTRAL OKLAHOMA
   TO FAR SOUTHERN KANSAS AND THE UPPER MISSISSIPPI RIVER VALLEY...

   CORRECTED FOR GENERAL THUNDER LINE

   ...SUMMARY...
   Isolated to scattered severe thunderstorms will be possible later
   this afternoon through this evening across a large portion of the
   central states. The most probable areas for large hail and damaging
   winds are across a portion of Oklahoma and southern Kansas, as well
   as from east-central Missouri to southwest Wisconsin.

   ...Discussion...
   The forecast generally remains on track with only minor adjustments
   required. Latest analyses and observations from central/southern OK
   show cool outflow from morning/ongoing convection lingers across the
   region with only modest recovery. Consequently, low-level lapse
   rates remain somewhat poor and may not recover sufficiently to
   support a widespread damaging wind threat. As a result, the 15% wind
   risk area is removed. However, thunderstorms developing this
   afternoon/evening will still pose a large hail risk with an
   attendant (albeit limited) damaging wind potential. 

   Across the upper MS river valley, latest GOES visible imagery shows
   cumulus beginning to deepen along the surface cold front from
   northern IL into WI. Low-level lapse rates in the region continue to
   steepen to near 8 C/km, which will support a damaging wind threat as
   storms develop along the front around late afternoon.

   ..Moore/Mosier.. 05/13/2022

   .PREV DISCUSSION... /ISSUED 1126 AM CDT Fri May 13 2022/

   ...OK to southern KS...
   Below-average confidence exists in how convective evolution will
   play out late this afternoon and evening. A quasi-stationary
   thunderstorm cluster has been persistent in a portion of
   east-central to northeast OK. While most 12Z guidance suggest this
   activity should gradually drift east and weaken this afternoon, some
   CAMs indicate renewed storm development will occur along its
   southwest flank in the south-central OK vicinity later this
   afternoon when differential heating should be maximized. Other
   guidance suggests convection will also develop farther
   west-northwest along the weakly convergent surface front in
   south-central KS to west-central OK during the 00-02Z time frame.
   Given weak low-level winds and nebulous large-scale ascent, these
   various scenarios appear plausible. Within a belt of 25-30 kt 500-mb
   westerlies, a few slow-moving supercells and multicell clusters may
   develop with large hail and damaging winds as the primary hazards. 

   ...WI to the Mid-MS Valley...
   An MCV near the MO/IA border should shift northeast into WI by this
   evening. A surface cold front will move east across WI and trail
   south-southwest into the Mid-MS Valley. Convergence along this
   boundary will be the primary forcing mechanism for a broken band of
   thunderstorms during the 23-02Z time frame. A relatively narrow
   plume of higher PW values evidenced in GOES imagery should be
   confined to along the surface boundary from the Mid-MO Valley south.
   Weak shear is expected in this region but should be compensated by
   larger buoyancy. The trailing influence of enhanced deep-layer shear
   attendant to the MCV should affect the WI/IA/IL border area north
   where MLCAPE will be subdued. Overall scenario suggests multicell
   clustering will dominate with a confined threat for isolated to
   scattered damaging winds and isolated severe hail.

   ...Lower MS Valley...
   Along a diffuse front aiding in low-level convergence, ongoing
   thunderstorms across western MS should expand in coverage from the
   AR/TN border south into southeast LA during the rest of the
   afternoon. Vertical shear will be weak, but a belt of 20-25-kt
   mid-level northerlies will support some multicell clustering.
   Localized damaging winds from wet microbursts will be the primary
   hazard, but isolated marginally severe hail will be possible as
   well.

   ...West TX...
   Hot temperatures to the west of the dryline will aid in scattered
   thunderstorms along the boundary during the late afternoon to early
   evening. Weak lower-level wind fields will minimize SRH, but
   sufficient deep-layer shear will exist for a few transient
   supercells and multicell clusters capable of isolated large hail and
   severe wind gusts.

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