SPC AC 091724

   Day 2 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1224 PM CDT Tue Jul 09 2024

   Valid 101200Z - 111200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM NORTHERN PA
   AND MUCH OF CENTRAL AND SOUTHERN NY INTO SOUTHERN NH/VT AND WESTERN
   MA....

   ...SUMMARY...
   Damaging gusts and a few tornadoes are possible mainly from northern
   Pennsylvania and much of central and southern New York into southern
   New Hampshire/Vermont and western Massachusetts.

   ...Synopsis...
   Upper troughing is expected to persist across the central and
   eastern CONUS on Wednesday, supported by a pair of shortwave troughs
   moving through the cyclonic flow aloft. Most prominent of these
   shortwaves is associated with the remnants of TC Beryl and is
   forecast to move quickly northeastward from its early period
   position over the Middle OH Valley and Lower MI through the Lower
   Great Lakes region and eastern Ontario. An associated surface low is
   expected to progress northeastward just ahead of its parent
   shortwave trough, moving from central IN/OH into the St. Lawrence
   Valley while occluding. Cold front attendant to this system will
   move eastward across the OH Valley and into the Mid-Atlantic.
   Secondary surface cyclogenesis is possible Wednesday afternoon at
   the triple point (which will likely be in the southwestern NY/Finger
   Lakes vicinity), with the resulting low tracking northeastward into
   northern NY.

   Farther west, upper ridging centered over southern NV is expected to
   build throughout the day, covering much of the western CONUS by
   early Thursday morning. Modest northwesterly flow aloft is
   anticipated between these two features over the High Plains, with
   associated lee surface troughing.

   ...Northern Mid-Atlantic into Upper OH Valley and Northeast...
   A occluded front will likely extend from the primary surface low
   near the northern/central IN/OH border east-northeastward to the
   triple point in the northeast OH/northwest PA vicinity early
   Wednesday morning, with a warm front continuing eastward from the
   triple point across southwest/south-central NY into MA. The
   associated warm sector is expected to be characterized by dewpoints
   in the upper 60s to low 70s, which are forecast to advect northward
   as the surface low pushes east and the warm front lifts north.
   Strong heating is anticipated within this warm sector as well, with
   afternoon temperatures in the upper 80s and low 90s. These
   thermodynamic conditions will support moderate to strong buoyancy
   throughout the warm sector, with MLCAPE around 2000 J/kg.

   Thunderstorm development is anticipated along the cold front, with
   some pre-frontal development within areas of low-level confluence
   possible as well. Deep-layer vertical shear across the warm sector
   will be moderate (i.e. around 30-40 kt from 0-6 km bulk shear),
   supporting the potential for organized storm structures and a few
   supercells. Warm temperatures aloft will likely mitigate the hail
   threat, but strong heating and resulting steep low-level lapse rates
   will support damaging gusts. Additionally, some backing of the
   surface winds (particularly near the warm front), could also result
   in enough low-level veering with height to result in some tornado
   potential. Greatest severe coverage is anticipated from southwest
   NY/northwest PA northeastward across much of central and southern NY
   into southern NH/VT and western MA.

   ...Portions of NM and west TX...
   Afternoon and evening thunderstorms development is possible across
   the region, beginning over the higher terrain, as the airmass
   destabilizes amid strong heating and a low-amplitude shortwave
   trough rounds the eastern periphery of the upper ridge. Buoyancy
   will be modest, but high cloud bases and steep low-level lapse rates
   will still support the potential for strong outflow capable of
   damaging wind gusts. A few small clusters could aggregate outflow
   for a couple hours to locally enhance the convective wind potential.
   The threat should wane quickly during the evening as the boundary
   layer stabilizes.

   ..Mosier.. 07/09/2024

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