SPC AC 040536

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1236 AM CDT Mon Jul 04 2022

   Valid 041200Z - 051200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE UPPER
   MIDWEST AND GREAT LAKES REGION AND ACROSS MT INTO THE NORTHERN HIGH
   PLAINS...

   ...SUMMARY...
   Isolated to scattered severe thunderstorms are expected from parts
   of the northern Rockies/Plains eastward into the Midwest and Great
   Lakes regions on Monday. Large hail and damaging winds should be the
   main threats.

   ...Midwest/Great Lakes Region...

   Early this morning, satellite imagery suggests two distinct
   short-wave troughs are progressing through the upper ridge across
   the northern/central Plains region. Each of these features will
   likely contribute to scattered robust convection that should spread
   across the upper Midwest into the Great Lakes region. Multiple
   thunderstorm clusters are ongoing across the Dakotas into eastern NE
   at 0530z. This activity will propagate into MN/IA early in the
   period as LLJ is drawn into this region in response to the
   progressive short waves. Flattening height field across MN/WI, and a
   strengthening LLJ across the Great Lakes during the latter half of
   the period, suggest multiple warm-advection thunderstorm clusters
   should advance downstream as air mass recovery contributes to
   buoyancy for robust updrafts. While deep-layer flow/shear would
   seemingly support supercell structures, storm mode will likely be
   larger clusters with the possibility for one or more MCSs. Damaging
   wind/hail are the primary threats if this scenario does unfold.

   ...MT into the northern High Plains...

   Upper ridge is forecast to build north across the Plains later today
   as upper troughing holds near the Pacific Coast. Latest model
   guidance continues to suggest seasonally strong southwesterly 500mb
   flow will extend across the northern Great Basin into central MT.
   While broad height rises are expected across the SLGT Risk region, a
   weak disturbance may approach western MT by peak heating. Strong
   surface heating across western MT should aid buoyancy within a moist
   boundary layer maintained by weak surface ridging over the western
   Dakotas. Isolated supercells should develop by mid-late afternoon
   over the higher terrain near HLN then spread/develop east toward the
   lower Plains region. Hail/wind should be noted with this activity as
   it propagates toward the western Dakotas. Some clustering is
   possible as convection spreads into eastern MT.

   ..Darrow/Karstens.. 07/04/2022

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