Storm Prediction Center Mesoscale Discussion 2272

   Mesoscale Discussion 2272
   NWS Storm Prediction Center Norman OK
   0554 AM CST Wed Dec 18 2024

   Areas affected...Tennessee Valley area

   Concerning...Severe potential...Watch unlikely 

   Valid 181154Z - 181430Z

   Probability of Watch Issuance...20 percent

   SUMMARY...A strong wind gust or two, or even a very brief/weak
   tornado, will be possible across the Tennessee Valley area this
   morning as a line of storms progresses across the region.  WW
   issuance is unlikely to be needed.

   DISCUSSION...Latest radar loop shows a semi-continuous band of
   thunderstorms advancing across western Kentucky/western Tennessee
   and the Arklatex region early this morning, near an advancing cold
   front.  The pre-frontal boundary layer is characterized by
   temperatures in the low 60s, and dewpoints in the mid to upper 50s
   (Kentucky and most of Tennessee) to the low 60s/northern
   Mississippi).  However, this degree of boundary-layer theta-e
   remains insufficient to allow truly surface-based convection, with a
   weak stable layer indicated in the 900 to 950mm layer. 

   Above the weak stable layer, modest elevated CAPE (around 500 J/kg)
   is indicated -- sufficient for widespread lightning and even
   vigorous/bowing segments within the line locally.  While the
   slightly elevated nature of the convection should continue to limit
   overall severe potential, the most organized segments within the
   line will be capable of producing gusty winds -- perhaps near severe
   levels locally.  Even a very brief/weak tornado cannot be ruled out,
   near one of the embedded bowing structures.  Still, with storms
   moving quickly through the Tennessee Valley area -- too soon to
   allow any appreciable pre-convective diurnal heating to occur -- it
   appears at this time that risk should remain too low to warrant WW
   consideration.

   ..Goss/Edwards.. 12/18/2024

   ...Please see www.spc.noaa.gov for graphic product...

   ATTN...WFO...LMK...OHX...HUN...MEG...

   LAT...LON   34799045 35888833 36718690 36808596 35998599 35508618
               34808817 34538948 34539050 34799045