SPC AC 271711

   Day 2 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1211 PM CDT Mon Jun 27 2022

   Valid 281200Z - 291200Z

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FOR PARTS OF THE
   UPPER MIDWEST/GREAT LAKES...AND ALSO FOR PARTS OF MONTANA...

   ...SUMMARY...
   Strong thunderstorms may impact parts of the Upper Midwest and Great
   Lakes Tuesday afternoon and evening, accompanied by at least some
   risk for severe hail and wind. Thunderstorms capable of isolated
   severe wind gusts will also be possible Tuesday afternoon and
   evening across parts of Montana.

   ...Synopsis...
   A mid/upper-level trough is forecast to amplify over the Great Lakes
   region on Tuesday, while to the west, another trough will move from
   the Pacific Northwest towards the northern Rockies. A cold front
   associated with the Great Lakes trough will move through parts of
   MN/WI, while a weak cold front attendant to the western trough
   begins to move through MT. Relatively dry and stable conditions are
   expected across much of the CONUS in the wake of an earlier cold
   frontal passage across the southern Plains and Southeast, though
   some severe thunderstorm potential may be associated with the
   passage of the mid/upper-level troughs noted above across parts of
   MT and the Upper Midwest/Great Lakes.

   ..Upper Great Lakes/Midwest...
   Diurnal heating and modest low-level moisture transport from the
   southwest will support weak to locally moderate destabilization
   across parts of WI/MN/IA and upper MI Tuesday afternoon. Scattered
   thunderstorm development is possible along/ahead of the cold front
   by late afternoon as an embedded shortwave within the larger-scale
   upper trough approaches from the northwest. Increasing midlevel
   northwesterly flow will support sufficient effective shear for
   organized storm potential. A couple of supercells and/or organized
   clusters will be possible, with an attendant risk of hail and
   locally damaging wind gusts as storms move southeastward across the
   region into early evening. The magnitude of the threat will depend
   on the extent of low-level moistening and destabilization that can
   occur across the region, which remains somewhat uncertain at this
   time. 

   ...Montana...
   High-based thunderstorms are expected to develop Tuesday afternoon
   across parts of western/central MT, as the mid/upper-level trough
   and associated surface trough/weak cold front move through the
   region. Instability will generally remain weak (MLCAPE less than 500
   J/kg) due to limited low-level moisture, but inverted-v profiles and
   increasing deep-layer shear will support outflow-dominant storm
   clusters capable of isolated severe wind gusts. This threat may
   spread as far as eastern MT Tuesday evening before storms weaken
   after sunset.

   ..Dean.. 06/27/2022

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