SPC AC 280727

   Day 3 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0227 AM CDT Sat Aug 28 2021

   Valid 301200Z - 311200Z

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS
   OF THE LOWER MS VALLEY AND SOUTHEAST AS WELL AS OVER PORTIONS OF THE
   MID MO RIVER VALLEY...

   ...SUMMARY...
   Tornadoes are possible within the right-front quadrant of tropical
   cyclone Ida across portions of the Lower Mississippi Valley and
   Southeast on Monday. Isolated severe storms are also possible across
   the Middle Missouri River Valley.

   ...Synopsis and Discussion...
   A remnant frontal zone should extend across the central Plains
   through the mid MS and OH Valleys and into the Northeast early
   Monday morning. Portion of this front over the Northeast should
   remain progressive, with thunderstorms expected along the boundary
   as it moves eastward. This region will likely be on the southern
   extent of the stronger flow aloft, and a few storms may become
   robust enough to produce damaging wind gusts. However, uncertainty
   regarding frontal timing and buoyancy preclude introducing any
   probabilities with this outlook. 

   Thunderstorms are also anticipated along this boundary across the OH
   and Mid MS Valley. Limited shear should mitigate overall storm
   strength. Stronger vertical shear is anticipated across the northern
   and central Plains, where low-level southeasterly flow should exist
   beneath more westerly/northwesterly flow aloft. This increase shear
   coupled with moderate buoyancy results in an environment favorable
   for strong to severe storms. Zonal flow is anticipated across the
   region, but guidance indicates a subtle, low-amplitude wave could
   move into the region and provide the ascent needed for storm
   initiation. 

   Farther south, guidance indicates that Hurricane Ida will still be
   impacting the Lower MS Valley and Southeast. Uncertainty exists
   regarding the extent and strength of destabilization within the
   front-right quadrant of the storm. However, strong low to mid-level
   flow will still exist throughout this portion of the storm and
   tornadoes will remain possible. Refinements to this risk area,
   including potentially higher probabilities, will likely be needed in
   later outlooks as mesoscale details become more predictable.

   ..Mosier.. 08/28/2021

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