SPC AC 131932

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0232 PM CDT Sun Oct 13 2024

   Valid 132000Z - 141200Z

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE
   NORTHERN APPALACHIANS INTO PARTS OF THE TENNESSEE VALLEY...

   ...SUMMARY...
   Strong to locally severe thunderstorms are possible, mainly this
   evening, from Pennsylvania southward to the Tennessee Valley.
   Isolated wind damage should be the main threat.

   ...20z Update...
   The previous forecast largely remains on track with only minor
   adjustments made. The 5% wind/Marginal risk area was expanded
   slightly across portions of central to northeast PA where morning
   cloud cover has cleared and allowed for stronger daytime
   heating/destabilization (denoted by temperatures in the upper 70s to
   low 80s). These observations appear to be well assimilated into
   recent HRRR/RRFS runs, which have trended towards a slightly
   stronger UH/convective signal compared to early-morning solutions.
   The risk lines have been adjusted to account for these recent
   trends.

   ..Moore.. 10/13/2024

   .PREV DISCUSSION... /ISSUED 1116 AM CDT Sun Oct 13 2024/

   ...Central/Southern Appalachians into the Tennessee Valley...
   Water vapor loop shows a fast-moving and deepening shortwave trough
   over WI.  This feature will dig southeastward across the Great Lakes
   region through the day, with fast flow aloft extending eastward
   across the central Appalachians.  A surface low currently over
   northern OH will track eastward across PA along a warm front, while
   an associated cold front sweeps southeastward across OH/WV/KY/TN. 
   Low-level moisture is quite limited ahead of this system, which will
   limit coverage and overall intensity of convection.  However, over
   half of morning CAM solutions suggest thunderstorm development along
   the front this afternoon and evening, where winds aloft and steep
   low-level lapse rates will promote a risk of locally gusty/damaging
   winds.  

   The MRGL risk area has been extended northeastward into parts of
   central/northeast PA, ahead of the surface low and along the warm
   front.  CAPE will be very weak in this area, but forecast soundings
   and some CAM guidance suggest the potential for 1 or 2 rotating
   storms capable of gusty wind or perhaps a brief spin-up around peak
   heating.

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