SPC AC 011937

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0237 PM CDT Sun Aug 01 2021

   Valid 012000Z - 021200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS LATE THIS
   AFTERNOON ACROSS PARTS OF THE CAROLINA COASTAL PLAIN...

   ...SUMMARY...
   Thunderstorm activity may continue to develop and organize across
   the  North Carolina coastal plain late this afternoon and pose a
   risk for damaging wind gusts.

   ...20Z Outlook Update...
   Adjustments have been made to the categorical and probabilistic
   outlook lines, mostly to the account for the progression of a number
   of synoptic and sub-synoptic perturbations and associated surface
   boundaries.

   Seasonably modest low-level moisture and boundary-layer warming are
   limiting destabilization across the Northeast, as a vigorous short
   wave trough gradually begins to turn east of the lower Great Lakes
   region.  However, there does still appear at least a window of
   opportunity for some intensification of ongoing convective
   development late this afternoon and evening, particularly across
   parts of southwestern into central Pennsylvania, as a 50 kt 500 mb
   jet streak propagates eastward out of central Ohio.

   Across Texas, vigorous thunderstorm development is ongoing along a
   weak southward advancing outflow boundary across the Edwards Plateau
   and Hill Country vicinity.  However, this is far removed from even
   the weak to modest (10-20 kt) west-northwesterly mid-level flow on
   the southern fringe of upper troughing across the Ark-La-Tex
   vicinity into the Gulf Coast states.  With thermodynamic profiles
   not much, if any, more conducive to downburst potential, severe
   weather probabilities appear comparatively weaker, and generally
   less than 5 percent.

   ..Kerr.. 08/01/2021

   .PREV DISCUSSION... /ISSUED 1120 AM CDT Sun Aug 01 2021/

   ...Carolinas...
   A few supercells have evolved into a small cluster along the surface
   front across northeast NC. Additional convective development is
   expected farther southwest near the surface cyclone across central
   NC. Air mass ahead of the front/cyclone continues to destabilize in
   the presence of mid to upper 70s surface dew points. While low-level
   SRH should remain modest, slightly backed surface winds across far
   eastern NC may support the threat for a tornado or two. The primary
   hazard will likely be scattered damaging winds as the upstream
   convection develops and evolves into an eastward-moving cluster
   across eastern NC through this afternoon.

   ...NY/PA...
   Lower-topped thunderstorms have developed along and just ahead of an
   eastward-progressing cold front in the lee of the Lower Great Lakes.
   More pronounced boundary-layer heating is underway across western to
   northeast PA into southeast/east-central NY, which should aid in
   some intensification of convection this afternoon. However,
   boundary-layer temperatures and dew points will be seasonally subpar
   with the bulk of destabilization occurring through steepening of
   mid-level lapse rates with approach of the shortwave trough. In
   addition, lower-level flow will remain relatively modest with faster
   mid-level flow largely confined to the upper portion of the weak
   buoyancy profile. As such, convection may struggle to become
   substantially deep and organized, which may result in only sporadic
   bouts of damaging winds and isolated marginally severe hail.

   ...Deep South...
   Scattered thunderstorms are expected along a trailing cold front
   that will slowly slide south across the region this afternoon. Weak
   deep-layer shear but large buoyancy will favor pulse to loosely
   organized multicells. Wet microbursts capable of producing locally
   damaging wind gusts will be the main hazard.

   ...West...
   In what is otherwise a weak meridional flow pattern across the West,
   a pair of MCVs, one over southeast NV and the other near the
   OR/ID/WA border area, may help focus weakly organized severe
   potential this afternoon. Relatively high PW values along with steep
   low-level lapse rates will support a threat for microbursts capable
   of isolated severe gusts.

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   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 0100Z