SPC AC 141647

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1147 AM CDT Tue Jul 14 2020

   Valid 141630Z - 151200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE UPPER
   MIDWEST/MIDDLE MISSOURRI VALLEY AND SOUTH-CENTRAL HIGH PLAINS...

   ...SUMMARY...
   Severe thunderstorms with damaging winds and large hail are expected
   this afternoon into tonight across the Upper Midwest from Iowa into
   Wisconsin, and across the south-central High Plains from southeast
   Colorado into southwest Kansas and the Texas/Oklahoma Panhandles.

   ...Eastern Kansas to Wisconsin/southeast Minnesota...
   A general trend of mid-level cooling and strengthening of
   west-southwesterly winds aloft will occur in conjunction with an
   eastward-moving trough over the Upper Midwest. Ahead of an
   eastward-moving cold front, considerable cloud cover/scattered
   convection persist at late morning from southern Minnesota into
   Wisconsin. The degree of destabilization is questionable with
   northeastward extent across Wisconsin, with more robust
   near/pre-frontal destabilization likely across Iowa southwestward
   into southeast Nebraska/northwest Missouri. 

   A few supercells may occur early in the storm evolution, but
   multicell clusters will be the primary storm mode, with an attendant
   threat for damaging winds and isolated large hail. A tornado or two
   could also occur. The southwest extent of diurnal storm development
   toward Kansas still remains uncertain, but a conditional wind/hail
   threat exists in the strongly buoyant environment. There is also
   some potential for elevated storm development overnight on the cool
   side of the boundary, and/or storms could spread northeastward along
   the boundary from southwest Kansas overnight toward parts of this
   region.

   ...Southeast CO/southwest KS and OK/TX Panhandles...
   An upslope flow regime will become increasingly established today
   along and immediately north of a cold front moving southward across
   western Kansas/eastern Colorado. Steep lapse rates and strong
   surface heating/mixing along the front, as well as the richer
   low-level moisture immediately north of the boundary, will result in
   a narrow corridor of 2500-3500 J/kg MLCAPE and weaker convective
   inhibition by mid-late afternoon. The more probable areas for
   initiation this afternoon will be along/south of the Palmer Divide
   to the Raton Mesa vicinity in southeast Colorado. This area will be
   south of the stronger mid-level westerlies, but northeasterly
   low-level winds will contribute to sufficient deep-layer shear for a
   few organized storms/supercells within the first few hours after
   initiation. Thereafter, upscale growth into an MCS appears likely as
   storms spread eastward toward southwest Kansas and the
   Oklahoma/northern Texas Panhandles. Large hail will be the main
   threat initially, with a transition to damaging winds (some
   significant-caliber wind gusts possible) expected this evening as
   storms cluster.

   ...Southern New England...
   A closed mid-level low will continue to drift east-southeastward
   over the region today, with modest destabilization evident on its
   southern periphery. Isolated severe thunderstorms capable of
   localized wind damage is the primary hazard, particularly across
   parts of Massachusetts/Connecticut/Rhode Isolated where instability
   is somewhat stronger. Reference Mesoscale Discussion 1222 for
   additional short-term details.

   ...Mississippi...
   A weak/southeastward-moving mid-level wave may influence isolated
   strong/locally severe thunderstorm development within a hot/very
   moist airmass. A few wet microbursts could produce localized damage
   this afternoon.

   ...Northern High Plains...
   A belt of moderately strong cyclonic flow aloft will influence the
   region today, with isolated thunderstorm development expected across
   the region later this afternoon. Instability will be weak,
   particularly by summer standards, but semi-long/straight hodographs
   could support a supercell and a marginally severe storm or two
   presuming adequate destabilization.

   ..Guyer/Bentley.. 07/14/2020

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