SPC AC 071938

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0238 PM CDT Sat Sep 07 2024

   Valid 072000Z - 081200Z

   ...NO SEVERE THUNDERSTORM AREAS FORECAST...

   ...SUMMARY...
   Organized severe thunderstorms are not forecast today, though a few
   strong gusts could accompany the more robust storms.

   ...20Z Update...
   The forecast remains on track, and only minor changes were made to
   the outlook with this update. In particular, the General Thunder
   line was trimmed behind the frontal rain band and associated wind
   shift in the Northeast, where cool post-frontal conditions have
   generally depleted instability. Updrafts within this band have
   remained too shallow/weak for an appreciable lightning risk thus
   far. However, an isolated strike still cannot be ruled out,
   especially over portions of eastern NJ and far southeastern NY/Long
   Island -- where filtered boundary-layer heating has occurred amid
   middle 60s dewpoints. Isolated/embedded strong gusts also remain
   possible (earlier 44 mph gust in eastern PA), though the
   weak/shallow updrafts (and associated downdrafts) should continue to
   limit the severe risk.

   Elsewhere, severe potential still appears too localized and/or
   marginal for severe probabilities. See the previous discussion below
   for details.

   ..Weinman.. 09/07/2024

   .PREV DISCUSSION... /ISSUED 1131 AM CDT Sat Sep 07 2024/

   ...Northeast...
   A cold front will move steadily east across the northeast today,
   accompanied by showers and thunderstorms.  Extensive cloud cover in
   advance of the front will tend to limit heating/destabilization,
   however modest MLCAPE (on the order of 250-500 J/kg) may develop
   from the northern Delmarva Peninsula north into southeast NY this
   afternoon.  Ascent with an upper-level trough will continue to move
   east in tandem with the front, and scattered thunderstorms may
   develop this afternoon with some potential for locally gusty winds. 
   Weak instability and poor low-level lapse rates should limit severe
   potential.

   ...Central High Plains...
   Low-level moisture will be generally modest east of a surface trough
   that will extend north-south across eastern portions of WY/CO this
   afternoon.  Still, lower 50s surface dew points and steep mid-level
   lapse rates should contribute to MLCAPE of 750-locally near 1000
   J/kg.  Isolated thunderstorms may form and move southeast within a
   northwest mid-level flow environment late this afternoon/evening,
   and a deep/well-mixed boundary layer suggests some potential for
   localized strong wind gusts.  Thunderstorm potential may extend
   eastward into western portions of NE/KS this evening as a low-level
   jet strengthens.  The overall coverage of any severe potential
   remains too low to introduce severe probabilities. 

   ...Interior Northwest...
   The potential for isolated thunderstorms, already ongoing this
   morning over south-central OR, will continue today as modest
   large-scale ascent associated with a mid-level trough overspreads
   inland areas of the Pacific Northwest. These storms may produce
   limited rainfall, exacerbating fire weather concerns.  

   ...Lower Colorado River Valley and Vicinity...
   Strong heating will contribute to scattered thunderstorm development
   this afternoon, and 12z hi-res guidance suggests that a couple of
   stronger storms or small clusters may have the potential for gusty
   outflow winds within a hot/well-mixed boundary layer.

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