SPC AC 140537

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1237 AM CDT Tue Jul 14 2020

   Valid 141200Z - 151200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE
   SOUTH-CENTRAL HIGH PLAINS TO THE UPPER MIDWEST...

   ...SUMMARY...
   Strong to severe storms are expected Tuesday from the south-central
   High Plains to the Upper Midwest.

   ...Upper Midwest...

   Weak height falls will spread across the upper MS Valley region
   during the day ahead of a short-wave trough that should extend from
   the MB/ON border into the eastern Dakotas by 15/00z. Models are in
   general agreement that a surface front should precede the short
   wave, advancing into northwestern WI - southeast MN - western IA by
   early afternoon. This boundary should serve as the focus for strong
   to severe thunderstorm development during the afternoon/evening
   hours. Prior to this development, substantial convection may be
   ongoing across portions of eastern SD into southern MN. This
   activity will likely be the remnants of ongoing convection currently
   observed over western SD. Extensive cloud debris and decaying precip
   shield should limit boundary layer heating across much of this
   region. Even so, a narrow corridor of somewhat steeper low-level
   lapse rates should evolve within the near-frontal warm sector from
   southwest IA into west-central WI. This is expected to aid buoyancy
   for potentially more robust convection. With a 60kt 500mb speed max
   forecast to approach western WI by late afternoon, wind profiles
   should support organized rotating updrafts and isolated supercells
   are expected. While a few tornadoes can not be ruled out, the
   primary severe risks will be wind/hail.

   ...South-central High Plains...

   Surface pressures will rise across the northern/central High Plains
   early in the period in the wake of ejecting short wave. Extensive
   precipitation within the post-frontal environment across SD should
   enhance the frontal surge which should advance into central KS,
   arcing into southeast CO by mid afternoon. Intense surface heating
   south of the wind shift will result in surface temperatures soaring
   well above 100F across the OK/TX Panhandle region. Convective
   temperatures will be easily breached in these areas. Frontal/upslope
   convergence is expected to aid thunderstorm development across
   southeast CO into the northern TX Panhandle. CAMs are reasonably
   consistent in this scenario and one or more thunderstorm clusters
   should spread east-southeast into the evening hours. There is some
   concern that severe wind probs may need to be increased across this
   region to account for high-based convection maturing downstream into
   an environment that will be quite moist/unstable. This will be
   considered in future updates.

   ...Southern New England...

   Seasonally cool upper trough will shift east across New England
   during the day. Latest guidance suggests low-level lapse rates will
   steepen quickly beneath this trough from CT into southern VT/NH.
   Forecast soundings suggest convection will develop early then drift
   southeast within a weak-flow regime. While marginally severe hail
   could be noted, the primary risk with this diurnally driven activity
   will be locally gusty winds.

   ..Darrow/Lyons.. 07/14/2020

   CLICK TO GET WUUS01 PTSDY1 PRODUCT

   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1300Z