SPC AC 131732

   Day 2 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1132 AM CST Fri Nov 13 2020

   Valid 141200Z - 151200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM FAR NORTHEAST
   OK ACROSS NORTHWEST AR INTO SOUTHERN MO...

   ...SUMMARY...
   Isolated severe thunderstorms may occur across eastern Oklahoma and
   the Ozarks/Ark-La-Tex regions late Saturday afternoon and night.

   ...Synopsis...
   A deep shortwave trough is forecast to move quickly across the
   Plains and into the Upper/Middle MS Valley on Saturday. This
   shortwave will be accompanied by a strong (i.e. 100 kt at 500 mb)
   jet, which will likely extend from eastern KS through the middle MS
   and southern OH Valleys, and into the Lower Great Lakes region early
   Sunday morning. 

   Surface cyclogenesis is anticipated ahead of this shortwave and
   attendant jet streak. The resulting low is forecast to develop over
   the mid MO Valley before then tracking quickly northeastward through
   the Upper Midwest. An associated cold front will sweep
   eastward/southeastward. By 00Z Sunday, this front will likely extend
   from the low over central IA southwestward through western MO and
   eastern OK. By 12Z Sunday, consensus of the guidance places the
   front from Lower MI south-southwestward into western TN and then
   back southwestward across the Lower MS Valley into the TX Hill
   Country.

   ...Eastern Oklahoma/Ozarks/ArkLaTex...
   Modest low-level moisture advection will be underway across the
   southern Plains at the beginning of the period. Southwesterly
   low-level flow will persist throughout the day from the southern
   Plains into the Mid MS Valley, contributing to continued moisture
   advection and the potential low 60s dewpoints into the Ozark Plateau
   ahead of the front. Current observations place the low 60s dewpoints
   in central TX, under north winds and weak cold advection. Early day
   showers and cloudiness are also expected from northeast OK into
   southern MO. As a result, there is some uncertainty whether low 60s
   dewpoints will actually be able to advect as far north as the models
   suggest.  

   Whether or not this is enough low-level moisture to support severe
   thunderstorms will also depend on the amount of heating the area
   receives. Current consensus within the guidance is for overcast
   conditions to hamper daytime heating, keeping temperatures in the
   low 60s (perhaps even upper 50s across northwest AR and southern
   MO). Given the resulting convective inhibition associated with those
   surface temperatures, updrafts would likely struggle to maintain
   depth and consistency, limiting the overall severe potential.

   In contrast to the marginal thermodynamics, kinematic fields are
   very supportive of organized storm structures with notable low-level
   curvature and long hodographs. Any updrafts that are able to
   maintain depth and consistency would likely pose a risk for damaging
   wind gusts and tornadoes. The overall scenario is conditional on
   destabilization but the strength of the wind fields merit upgrading
   to a 5% tornado/15% wind Slight Risk.

   ..Mosier.. 11/13/2020

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