SPC AC 270719

   Day 3 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0219 AM CDT Sat Jul 27 2024

   Valid 291200Z - 301200Z

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ALONG THE
   MISSISSIPPI RIVER FROM SOUTHEAST MINNESOTA AND WESTERN WISCONSIN TO
   THE MISSOURI BOOTHEEL...

   ...SUMMARY...
   Scattered strong to severe storms are possible in portions of the
   Midwest on Monday.

   ...Synopsis...
   On Monday, a broad, low-amplitude ridge will be centered across the
   High Plains with a trough axis near the Pacific Coast and a trough
   across the Ohio Valley and the East Coast. As the East Coast
   upper-level low continues to retrograde during the day, these
   features will phase into one larger trough across the eastern CONUS.
   Several embedded mid-level shortwave troughs will traverse the
   northern CONUS and Canadian Prairies into the northwest flow across
   the Midwest. 

   ...Midwest...
   Rich Gulf moisture will become well established across the Midwest
   by Monday with dewpoints in the mid 70s. This will result in a very
   unstable environment with MLCAPE 3000+ J/kg across portions of the
   Upper Mississippi River Basin. This strongly unstable environment
   will develop beneath 25 to 40 knots of mid-level flow which will
   provide ample shear for storm organization. However, despite a
   favorable severe weather parameter space that is expected within a
   broad zone across the Midwest, the details remain highly uncertain.
   Thunderstorms will be likely Monday morning given the strong
   low-level jet across Missouri and Iowa Sunday night. It is unclear
   whether this convection may simply stabilize portions of the risk
   area and lessen the severe weather threat, or if upscale growth can
   occur and persist into the late morning and if a severe MCS can
   develop from this activity and move southward along the Mississippi
   River vicinity. However, if this does not occur and substantial
   destabilization is able to occur farther north, the greatest severe
   weather threat may be focused near southeast Minnesota, southwest
   Wisconsin, eastern Iowa and northwest Illinois. The GFS favors this
   scenario with suppression of southern convection and a mid-level
   shortwave trough moving through southern Minnesota Monday afternoon.
   However, the ECMWF has a stronger southern-stream trough Monday
   morning which aids in greater storm maintenance across Missouri and
   southern Illinois. These inconsistencies are likely tied to
   Day2/Sunday convection across the Plains and therefore, it may not
   be clear where the greatest threat is until closer to the Day 1
   period. A broad marginal risk across the region with the most
   favorable environment seems like the most appropriate outlook until
   mesoscale details become more clear.

   ..Bentley.. 07/27/2024

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