SPC AC 180730

   Day 3 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0230 AM CDT Sat Jul 18 2020

   Valid 201200Z - 211200Z

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
   SOUTHERN NEW ENGLAND INTO THE MID-ATLANTIC...AND FROM THE MID
   MISSISSIPPI VALLEY INTO THE NORTHERN/CENTRAL PLAINS...

   ...SUMMARY...
   Isolated strong to severe thunderstorms appear possible Monday
   across parts of southern New England into the Mid-Atlantic, and from
   the mid Mississippi Valley into the northern/central Plains.

   ...Southern New England into the Mid-Atlantic...
   An upper trough/low should continue ejecting northeastward across
   eastern Canada and the northeastern CONUS on Monday. A surface cold
   front is likewise forecast to advance across the Northeast through
   the day. There is some uncertainty regarding the forward progression
   and placement of this front by Monday afternoon. Even so, a very
   moist low-level airmass should be in place ahead of the front, which
   coupled with diurnal heating, will support at least moderate
   instability by Monday afternoon. This appears most probable across
   parts of southern New England into the Mid-Atlantic, and modestly
   enhanced mid-level winds may promote some storm organization.
   Isolated strong to damaging winds may occur with any storms that can
   form in this regime before moving offshore and weakening.

   ...Mid Mississippi Valley into the Northern/Central Plains...
   A weak boundary should be draped from the OH Valley westward into
   the mid MS Valley and central Plains on Monday. Large-scale forcing
   for ascent will remain weak over much of these regions. Still,
   strong heating of a moist low-level airmass south of the weak front,
   and localized enhancements to the mid-level flow from prior days'
   convection may allow for modest storm organization, given the
   forecast instability that should be present. There appears to be
   some potential for better storm organization and intensity across
   parts of the northern/central Plains as a low-amplitude shortwave
   trough advances southeastward across this region through the period.
   However, there is considerable uncertainty regarding the degree of
   low-level moisture return and related instability, as well as
   convective coverage. For now, will depict a fairly broad 5% severe
   area, with some potential for higher probabilities as mesoscale
   details become better resolved.

   ..Gleason.. 07/18/2020

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   NOTE: THE NEXT DAY 3 OUTLOOK IS SCHEDULED BY 0730Z