SPC AC 130546

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1246 AM CDT Sun Oct 13 2024

   Valid 131200Z - 141200Z

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM
   CENTRAL/EASTERN WV TO MIDDLE/EASTERN TN...

   ...SUMMARY...
   Strong to locally severe thunderstorms are possible, mainly this
   evening, across parts of the central/southern Appalachians and
   Tennessee Valley. Isolated wind damage and marginally severe hail
   are the expected hazards.

   ...Central/southern Appalachians and the TN Valley...
   A vigorous shortwave impulse will dig through the basal portion of a
   mid/upper trough and yield amplification of this trough southward
   across the Great Lakes through Monday morning. Appreciable mid-level
   height falls will overspread the central/southern Appalachians into
   the TN Valley, mainly during the evening and overnight. A leading
   and weaker mid-level impulse should yield the primary surface
   cyclone moving east across PA during the afternoon to early evening.
   A surface cold front will extend southwest of this low into the TN
   Valley. Convective development along the front appears likely to be
   delayed until early evening, as the strengthening large-scale ascent
   aids in increasing low-level convergence along the boundary amid
   pervasive veered flow within the warm sector. Surface dew points
   should largely range from the mid 50s in WV to a narrow corridor of
   low 60s in Middle TN, yielding a plume of modest buoyancy between
   500-1500 J/kg amid initially steep mid-level lapse rates. 

   Guidance differs greatly in the degree of storm coverage, from nil
   to scattered, perhaps in response to the ascent strengthening after
   peak diurnal heating. The strongest 700-mb westerlies, in excess of
   50 kts, should be confined northeast of TN. Forecast hodographs
   above this level appear small, owing to weakening winds with height
   as fast mid/upper flow lags to the north-northwest. This suggests
   supercell structures may struggle to develop/be sustained. But the
   strong 700-mb flow could support localized damaging winds in any
   multicell clusters. Farther southwest, somewhat greater buoyancy
   could foster small to marginally severe hail as well. The overall
   severe threat appears likely to remain marginal and isolated.

   ..Grams/Halbert.. 10/13/2024

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