SPC AC 311734

   Day 2 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1234 PM CDT Mon Aug 31 2020

   Valid 011200Z - 021200Z

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM A PORTION
   OF THE SOUTHERN PLAINS INTO THE TENNESSEE AND OHIO VALLEY REGIONS...

   ...SUMMARY...
   A few strong to severe storms capable of mainly severe gusts and
   hail will be possible over a portion of the southern Plains Tuesday.
   Other storms with a few locally strong to severe gusts will be
   possible over a portion of the Tennessee and Ohio Valleys.

   ...Southern Plains region...

   Thunderstorms will likely be ongoing along and south of a stalled
   front from the lower MS Valley region into southern OK and northern
   TX, possibly extending westward through a portion of western TX. A
   moist warm sector will reside south of ongoing storms across
   northern through central TX where the atmosphere will likely become
   moderately unstable. Activity will likely continue developing slowly
   south during the day with potential for a few locally strong gusts.
   However, belt of modest southwest mid-upper flow will reside over
   this region downstream from an upper low amplifying across the 4
   corners region. With only modest flow aloft parallel to outflow
   boundary and presence of weak vertical shear, overall threat does
   not seem to warrant more than a MRGL risk category.

   Farther west, overall severe threat will depend on extent of morning
   convection. However, current indications are that a corridor of
   moderate instability may develop in vicinity of a dryline feature
   across western TX where steeper mid level lapse rates will exist.
   Additional storms may develop along this feature during the
   afternoon, and effective bulk shear from 30-40 kt could support a
   few rotating updrafts capable of large hail and strong wind gusts.
   Due to uncertainty regarding extent of early convection and residual
   clouds, will maintain MRGL risk category this update, but an upgrade
   to SLGT might be warranted in day 1 outlooks.  

   ...Tennessee and Ohio Valley regions...

   Thunderstorms will likely be ongoing south of a stalled front from
   the lower and middle MS valley into the western TN and OH Valley
   regions. A shortwave trough will advance northeast through this
   region during the day augmenting vertical wind profiles. Primary
   uncertainty this outlook for a more robust severe threat is
   destabilization potential, given weak lapse rates and expected
   widespread clouds. Some destabilization is possible, but
   thermodynamic profiles will likely remain marginal. Nevertheless, a
   few strong storms could develop during the afternoon where
   sufficient boundary layer warming occurs. Vertical wind profiles in
   association with the progressive shortwave trough might become
   sufficient for a few organized structures with damaging wind and
   perhaps a brief tornado or two the main threats.

   ..Dial.. 08/31/2020

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