SPC AC 101624

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1124 AM CDT Sat Oct 10 2020

   Valid 101630Z - 111200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON
   INTO THIS EVENING FOR PARTS OF AL/WESTERN GA/FL PANHANDLE...AS WELL
   AS UPSTATE NY INTO NORTHERN NEW ENGLAND...

   ...SUMMARY...
   A few tornadoes are possible into this evening across parts of
   Alabama, western Georgia, and the Florida Panhandle. Damaging
   thunderstorm winds are possible across parts of northern New York
   and northern New England from mid afternoon into this evening.

   ...AL/FL Panhandle/western GA through late evening...
   The weakening remnants of tropical cyclone Delta will move generally
   eastward across northern MS today to northern AL tonight.  The
   system has a more baroclinic structure now with a warm front
   extending eastward from roughly Birmingham to Atlanta, and the
   primary surface trough near the MS/AL border.  Most of the
   convection is focused in a north-south band across central/southern
   AL and the western FL Panhandle in the zone of strongest low-level
   confluence/convergence.  Expect the main threat for embedded
   rotating storms to be focused within this band this afternoon as the
   stronger forcing for ascent spreads northeastward, and along the
   warm front as more isolated storms form in response to daytime
   heating in cloud breaks.  The combination of boundary-layer
   dewpoints in the low-mid 70s, weak buoyancy (MLCAPE of 500-1000
   J/kg), and sufficiently strong flow/shear east of the center of
   Delta will support a threat for occasional supercells and tornadoes
   this afternoon through late evening.

   ...Upstate NY into northern New England this afternoon/evening...
   A midlevel shortwave trough over the upper Great Lakes and ON will
   progress eastward over upstate NY and northern New England this
   afternoon through early tonight.  The midlevel trough will be
   accompanied by a surface cold front, with a narrow corridor of
   low-level moistening and modest destabilization expected along and
   just ahead of the front.  Though boundary-layer dewpoints will
   remain in the 50s, daytime heating and midlevel lapse rates of 7-8
   C/km will support MLCAPE of 500-1000 J/kg.  Deep-layer vertical
   shear will increase in this same corridor this afternoon, with
   effective bulk shear increasing to 50-60 kt with 50 kt flow within
   1-2 km of the ground.  Scattered thunderstorm development is
   expected along and just ahead of the front by mid afternoon across
   upstate NY, and storms will subsequently spread eastward across
   northern New England through this evening.  Storms will consist of a
   mix of supercells and line segments, with the primary threat for
   damaging winds.

   ..Thompson/Bentley.. 10/10/2020

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