ZCZC SPCSWOD48 ALL
   ACUS48 KWNS 100850
   SPC AC 100850

   Day 4-8 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0350 AM CDT Wed Jul 10 2024

   Valid 131200Z - 181200Z

   ...DISCUSSION...
   An upper-level ridge will gradually shunt eastward from the southern
   Rockies into the southern Plains and Lower MS Valley areas this
   weekend into the middle of next week. Multiple pronounced mid-level
   shortwave troughs and associated 500 mb speed maxima will pivot
   around the upper ridge and traverse the Upper MS Valley into the
   Northeast this weekend through early to mid next week. With adequate
   low-level moisture and overall instability preceding the mid-level
   troughs, severe thunderstorms are possible from the Upper MS Valley
   to the Northeast at least this weekend, possibly into early next
   week.

   ...Days 4-5 (Saturday-Sunday) - Upper MS Valley...
   A 500 mb speed max will traverse the U.S./Canada border on Day 4
   (Saturday) as surface lee troughing advects dewpoints well into the
   70s F across the northern Plains into the Upper MS Valley. An EML
   will also precede the mid-level speed max and overspread the rich
   low-level moisture, contributing to 4000+ J/kg MUCAPE per latest
   medium-range guidance consensus. Forcing for ascent will be modest
   and capping will be present, though the approach of the speed max
   may support convective initiation across the northern Plains into
   the Great Lakes region. At the moment, too much disagreement exists
   between medium-range guidance members regarding the placement of
   convection to support the addition of severe probabilities for
   Saturday.

   Despite some timing issues, medium-range guidance is in better
   agreement in depicting a mid-level impulse and accompanying wave of
   deep-moist convection traversing the Upper MS Valley area on Day 5
   (Sunday). There is some concern that preceding convection from Day 4
   could promote stability over portions of the Upper MS Valley into
   the Great Lakes. Nonetheless, both the ECMWF and GFS agree that the
   EML will continue regenerate from the southwest, focusing strong to
   potentially extreme instability into portions of this region. At the
   moment, it appears the best chance for severe convection (including
   the possibility of an organized, sustained MCS) would be over
   central MN into WI Sunday afternoon or evening, warranting the
   introduction of 15 percent severe probabilities. However, these
   probabilities may need to be considerably adjusted based on
   timing/placement changes of key mesoscale features, or to account
   for any impacts from preceding convection in later outlooks.  

   ...Days 6-8 (Monday-Wednesday) - Northern Plains to the Northeast...

   The first mid-level impulse will eject into the Northeast on Day 6
   (Monday). Some instability will precede this impulse, and
   medium-range guidance suggests that convective precipitation is
   possible. However, given limited deep-layer shear and ascent,
   confidence is too low to provide severe probabilities. Meanwhile,
   medium-range guidance consensus hints at convective development over
   parts of the northern Plains toward the Great Lakes on Monday as a
   second mid-level impulse impinges on the region. Though guidance
   consensus shows adequate overlapping shear and instability to
   support severe storms, relatively weak forcing for ascent and
   convective signals in the guidance preclude severe probabilities. By
   Days 7-8 (Tuesday-Wednesday), the second approaching mid-level
   trough will amplify while overspreading the Great Lakes, supporting
   a southward-surging cold front from the MS Valley into the
   northeast. Forcing for ascent and accompanying buoyancy suggests
   severe thunderstorms are possible from the MS Valley to New England.
   However, details on frontal timing and placement this far in advance
   are too nebulous for severe probabilities at this time.

   ..Squitieri.. 07/10/2024

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