SPC AC 140542

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1242 AM CDT Fri Aug 14 2020

   Valid 141200Z - 151200Z

   ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FROM FAR
   EASTERN NORTH DAKOTA INTO MUCH OF MINNESOTA...

   ...SUMMARY...
   Severe thunderstorms with damaging wind and hail, and perhaps a few
   tornadoes, will be possible from North Dakota this morning into
   Minnesota and the mid Missouri Valley this afternoon and evening.
   Marginally severe thunderstorms will be possible in parts of the
   central Plains and into the Texas Panhandle.

   ...Synopsis...
   A vigorous mid/upper-level shortwave trough is forecast to move from
   the northern High Plains into the upper MS Valley by tonight, as an
   attendant surface low moves from the Dakotas into the upper Great
   Lakes region and a cold front moves through the northern Plains.
   Elsewhere, an upper ridge will remain in place over the Southwest,
   while a weak upper trough persists over the East. 

   ...Northern/central Plains into the Upper MS Valley...
   One or more thunderstorm clusters will likely be ongoing across ND
   this morning in advance of the approaching shortwave trough, while
   elevated convection will also likely be persisting across some part
   of central/northern MN. The influence and evolution of the morning
   storms and their related outflow casts considerable uncertainty on
   the severe threat later in the day. 

   However, a substantial severe weather threat may evolve across
   central/northern MN if sufficient airmass recovery can occur by
   afternoon. Increasing flow in the lower-mid troposphere in response
   to the approaching shortwave and attendant surface low will enhance
   deep-layer shear and low-level shear/helicity by early afternoon.
   Steep midlevel lapse rates will support moderate-to-strong buoyancy
   if sufficient heating can occur. 

   Any ongoing complex across ND will likely move east-northeastward
   through the morning, posing a threat of damaging wind and perhaps
   some hail. This threat could persist into northwest MN by early
   afternoon, with a corridor of severe/damaging wind possible along
   its track. Additional development is expected further south along
   the cold front by mid/late afternoon, with shear profiles initially
   favoring a semi-discrete mode and the potential for supercells
   posing a threat of large hail (possibly significant) and locally
   damaging wind gusts. Any supercells in the vicinity of a potentially
   retreating outflow boundary will also pose a tornado threat,
   especially if the boundary sets up across central or northern MN,
   where wind profiles would be more favorable compared to areas
   further south. Convection may take on a more linear mode with time,
   which would result in damaging wind eventually becoming the primary
   threat. 

   Storms will spread into western WI by evening, with a gradually
   decreasing severe threat. Convection may also build into portions of
   eastern NE/western IA along the front by early evening, and spread
   southeastward with a threat of hail and locally damaging wind.  

    ...Central/southern High Plains...
   Widely scattered thunderstorm development is expected late this
   afternoon along the cold front across western KS, and further
   southward into the TX Panhandle where strong heating will erode weak
   MLCINH. Steep low-level lapse rates and large DCAPE will support a
   threat of isolated downbursts, while steep midlevel lapse rates may
   support some hail potential, especially across western KS where
   northwesterly midlevel flow is forecast to be somewhat stronger. 

   ...ArkLaTex into Mississippi...
   Elevated convection will likely be ongoing at the start of the
   period somewhere in the ArkLaTex vicinity. Instability and
   deep-layer shear will be sufficient to support an isolated wind/hail
   threat for at least a few hours this morning. There is some
   potential for an outflow-driven cluster, aided by a low-amplitude
   midlevel shortwave trough, to progress further southeast into MS
   through the day, which could pose a threat of locally damaging wind.

   ..Dean/Bentley.. 08/14/2020

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