SPC AC 180547

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1147 PM CST Tue Dec 17 2024

   Valid 181200Z - 191200Z

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
   THE TENNESSEE VALLEY...

   ...SUMMARY...
   Isolated damaging wind gusts and a brief tornado are possible
   through mid-day across parts of the Tennessee Valley.

   ...Tennessee Valley...
   A mid-level trough will move into the mid Mississippi Valley today,
   as an associated cold front advances southeastward through the Ohio
   and Tennessee Valleys. At the start of the period, a line of
   thunderstorms is expected to be located from central Kentucky
   southwestward across western Tennessee into eastern Arkansas. This
   line will move eastward toward the southern Appalachians this
   morning. Although instability is forecast to weaken ahead of the
   line during the morning, the southern edge of the low-level jet is
   expected to be over Tennessee where surface dewpoints will be in the
   mid to upper 50s F. This should be enough to maintain a marginal
   severe threat this morning. RAP forecast soundings in middle
   Tennessee at 15Z have curved hodograhps, with storm-relative
   helicity near 300 ms/s2 and 0-6 km shear around 40 knots. This
   environment should support isolated severe storms along the more
   organized parts of the line. The stronger cells embedded in the line
   could produce isolated severe gusts and potentially a brief tornado.
   This line, along with the severe threat, is expected to weaken by
   midday as the stronger low-level flow moves northeastward away from
   the region.

   ..Broyles/Lyons.. 12/18/2024

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