SPC AC 300559

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1259 AM CDT Sun Aug 30 2020

   Valid 301200Z - 311200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS EASTERN
   SD...CENTRAL/EASTERN NE...AND FAR NORTH-CENTRAL KS...

   ...SUMMARY...
   Strong to severe storms will be possible over parts of the Great
   Plains Sunday afternoon and evening, with damaging wind gusts and
   large hail the main threats.

   ...Northern/Central Plains...
   Shortwave trough currently moving into the northern Rockies is
   expected to continue eastward/southeastward throughout the day,
   reaching the northern Plains by late Sunday afternoon. A cold front
   will precede this shortwave, likely stretching from eastern ND
   south-southwestward to the southern KS/CO border. A well-defined
   elevated mixed layer will be in place, but strong heating and deep
   boundary-layer mixing is expected to result in an erosion of much of
   the convective inhibition ahead of the front by the late afternoon.
   Ascent along the front, augmented by large-scale forcing for ascent
   attendant to the approaching shortwave tough, will interact with
   this destabilizing air mass, resulting in convective initiation. 

   The strength of the buoyancy suggests initial updrafts will be
   strong enough to produce hail, including the potential for a few
   instances of significant hail. However, these updrafts will also
   develop in the presence of notable mid-level dry air, and the
   resulting dry air entrainment is expected to impede overall updraft
   strength as well as promote the development of strong downdrafts.
   Additionally, the stronger shear will likely lag the surface front.
   These factors merit leaving out any significant hail areas with this
   outlook. Severe thunderstorms are still expected to during the late
   afternoon and evening along the front from central ND into central
   KS. Highest coverage of severe storms is currently expected to occur
   over eastern SD into central/eastern NE. 

   ...Southern Plains into the TN Valley...
   Pair of ongoing mesoscale convective systems, one approaching the
   Red River border of TX and OK and the other moving into far
   northeast TX and southwest AR, will likely influence thunderstorm
   potential today along the remnant front extending from northwest TX
   into middle TN. Current trends suggest the remnants of western MCS
   will continue eastward through the Arklatex and Mid MS Valley.
   Thunderstorm development in the Arklatex appears less likely given
   the overturning that is occurring right now, with higher potential
   farther east into the mid MS Valley and adjacent TN Valley. The
   overall environment in this area will be moderately unstable and
   weakly sheared, supporting the possibility of a few storms capable
   of damaging wind gusts. Overall severe coverage is expected to be
   limited by the marginal environment. 

   Farther west, isolated thunderstorms are possible amidst the deeply
   mixed environment over all the TX/OK Panhandles. Convergence along
   the surface trough/dryline combined with ascent from a convectively
   induced shortwave trough approaching the region could result in
   isolated convective initiation. As a result, a conditional severe
   risk for hail and/or strong wind gusts will exist late this
   afternoon through this evening.

   ..Mosier/Karstens.. 08/30/2020

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