SPC AC 170728

   Day 3 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0228 AM CDT Tue Sep 17 2024

   Valid 191200Z - 201200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS IN A PART OF THE
   UPPER MIDWEST...

   ...SUMMARY...
   Scattered severe thunderstorms are possible from mid-afternoon to
   early evening on Thursday across central to eastern Minnesota and
   north-central Iowa.

   ...Upper Midwest...
   A vertically stacked cyclone near the ND/SK/MB border should move
   northeast over MB through the period. Predictability has increased
   with the placement of the trailing cold front arcing south on
   Thursday afternoon. In the mid-levels, modestly steepened lapse
   rates should overspread this boundary within a belt of moderately
   enhanced west-southwesterly flow. Given a confined plume of rich
   boundary-layer moisture, a corridor of MLCAPE from 1500-2500 J/kg
   should develop by mid-afternoon. Guidance consensus suggests
   scattered thunderstorms should form along the MN portion of the cold
   front towards mid to late afternoon amid an upper-level difluent
   flow regime. More isolated activity may occur southward into the Mid
   to Lower MO Valley. 

   A vertically veering wind profile with height should support
   supercells with a primary initial risk of large hail. With
   relatively modest upper-level winds and the expected coverage of
   storms along the front, upscale growth into linear clusters will be
   possible with a corresponding increase in damaging winds. A couple
   tornadoes may occur given adequate low-level hodograph curvature and
   the moist boundary layer. 

   The overall severe threat may diminish relatively rapidly after
   sunset. With neutral mid-level height change as the MB cyclone pulls
   away, in conjunction with progged weakening of 700-mb wind fields
   after 00Z, convective intensity should wane. This will likely be
   further aided by the confined buoyancy plume and drier airmass east.

   ..Grams.. 09/17/2024

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   NOTE: THE NEXT DAY 3 OUTLOOK IS SCHEDULED BY 1930Z