SPC AC 261626

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1126 AM CDT Fri Mar 26 2021

   Valid 261630Z - 271200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON
   ACROSS UPSTATE NY AND VT...

   ...SUMMARY...
   Damaging winds will be possible this afternoon across upstate New
   York and Vermont.  Elsewhere, isolated strong to severe
   thunderstorms may occur today across parts of the Southeast today,
   and across the central Plains and lower Mississippi Valley late this
   afternoon into tonight.

   ...Upstate NY/VT this afternoon...
   A pronounced midlevel shortwave trough and associated 995 mb surface
   cyclone will move quickly east-northeastward across upstate NY and
   northern New England this afternoon/evening.  A narrow corridor of
   surface heating and cloud breaks will spread northward/northeastward
   into upstate NY and parts of VT this afternoon, immediately in
   advance of the zone of ascent with the shortwave trough/surface
   cyclone.  A band of storms with embedded bows and/or low-topped
   supercells is expected to evolve this afternoon across upstate NY,
   with an associated threat for damaging winds, given SBCAPE of
   500-1000 J/kg, effective bulk shear in excess of 50 kt, and 50 kt
   flow within a few thousand feet of the ground.  Low-level shear may
   also be strong enough for a brief tornado with embedded small-scale
   circulations.

   ...Southeast AL/GA/Carolinas today...
   A broken band of storms is ongoing from central GA into central SC
   and eastern NC, along and just ahead of a weak, slow-moving cold
   front.  The primary associated shortwave trough is passing well
   north of this region, and forcing for ascent appears to be near or
   past peak.  Still, lingering moderate buoyancy and deep-layer
   west-southwesterly shear could support the potential for isolated
   damaging gusts and marginally severe hail, prior to the storms
   weakening by this evening.

   ...Northern KS/southeastern NE this evening...
   A lead shortwave trough over the central High Plains will eject
   east-northeastward today into early tonight, which will help
   maintain weak surface cyclogenesis across western KS through this
   afternoon.  Moisture return in the warm sector will remain quite
   limited in the wake of a prior frontal passage, but strong surface
   heating and boundary-layer dewpoints of 48-50 F could support weak
   surface-based buoyancy by late afternoon into central KS.  Surface
   heating/mixing could be sufficient for thunderstorm development
   along the surface warm front to the east of the triple point by this
   evening, where profiles would favor low-topped supercells. 
   Otherwise, the more probable scenario is for elevated convection
   this evening into early tonight across northeast KS and vicinity, in
   the warm advection zone (north of the surface front) on the nose of
   a developing low-level jet.  

   ...Mid South late tonight...
   The stalling front near the northern Gulf coast will begin to return
   northward as a warm front tonight, in response to strengthening
   southerly low-level flow downstream from a southern Rockies midlevel
   trough.  The increase in low-level flow will likewise support
   strengthening warm advection, and an increasing potential for
   thunderstorm development north of the warm front overnight into the
   Mid South.  The returning moisture and lingering midlevel lapse
   rates greater than 7 C/km will contribute to MUCAPE of 1500-2000
   J/kg, and the potential for a few strong updrafts.  Cells/clusters
   overnight will have the potential to produce isolated large hail,
   especially if any elevated supercells form given effective bulk
   shear of 35-40 kt.

   ..Thompson/Lyons.. 03/26/2021

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