SPC AC 301240

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0740 AM CDT Thu Jul 30 2020

   Valid 301300Z - 311200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS PARTS OF OK AND AR
   INTO WESTERN NORTH TX...

   ...SUMMARY...
   Severe thunderstorms with primary hazards of wind and hail are most
   likely from western north Texas across parts of Oklahoma and
   Arkansas during the late afternoon and evening. Locally damaging
   winds are also possible from Kentucky/Tennessee into parts of the
   Northeast this afternoon into tonight.

   ...Southern Great Plains to the Mid-South...
   A shortwave trough over the central High Plains will amplify as it
   reaches OK early Friday. Multiple convectively induced perturbations
   exist to the southeast of this trough, the most prominent of which
   should shift east from northeast OK. Attendant to this latter MCV, a
   leading surge of convective outflow extends to the west-southwest
   across the southern TX Panhandle. This boundary should be the focus
   for late afternoon thunderstorm development as surface temperatures
   breach 100 F to its south across western to north TX. To the north
   of the boundary in OK, the western extent of rich low-level moisture
   beneath an elevated mixed-layer will support large buoyancy with
   MLCAPE reaching 2500-3000 J/kg. Outflow-dominated clusters should
   develop from northwest TX across southern OK during the late
   afternoon and early evening with scattered severe wind gusts being
   the primary threat. More isolated severe wind gusts will also be
   possible into the Mid-South where convection redevelops at peak
   heating near the eastward-moving MCV from OK. 

   A secondary area of convection should develop in closer proximity to
   the shortwave trough over the south-central High Plains as surface
   convergence strengthens ahead of an anticyclone building into
   eastern CO. As this activity impinges on the reservoir of larger
   buoyancy in western OK, within a belt of 40-kt mid-level westerlies,
   thunderstorm clusters producing severe hail and wind may spread east
   across parts of OK this evening.

   ...KY/TN to the Southern Appalachians...
   An MCV over southern IL should drift east today. Convection is
   ongoing across the Lower OH Valley and is expected to increase in
   both coverage and intensity as the boundary-layer destabilizes.
   While weak mid-level lapse rates will curtail buoyancy downstream of
   the ongoing convection, a belt of moderate mid-level westerlies
   should support scattered multicell clusters capable of producing
   locally damaging winds. Additional rounds of isolated damaging winds
   may also linger this evening into tonight with convection that
   spreads east from the Mid-South.

   ...PA to southern New England...
   A weakly convergent frontal boundary should aid in isolated late-day
   thunderstorms. Buoyancy will be limited by rather poor mid-level
   lapse rates. But a robust combination of boundary-layer heating and
   speed shear should support a few cells with mid-level updraft
   rotation. Locally damaging winds and small hail are the most likely
   hazards.

   ..Grams/Jewell.. 07/30/2020

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