Storm Prediction Center Mesoscale Discussion 2269

   Mesoscale Discussion 2269
   NWS Storm Prediction Center Norman OK
   1001 PM CST Sun Dec 15 2024

   Areas affected...parts of northeastern Oklahoma...northwestern
   Arkansas...southern Missouri

   Concerning...Severe potential...Watch unlikely 

   Valid 160401Z - 160630Z

   Probability of Watch Issuance...5 percent

   SUMMARY...A substantive increase in thunderstorm development appears
   likely across the Ozarks Plateau vicinity into adjacent lower Ohio
   Valley during the Midnight-3 AM CST time frame.  Initially this may
   include widely scattered strong storms posing a risk for marginally
   severe hail, particularly across parts of northeastern Oklahoma into
   southwestern Missouri and adjacent northwestern Arkansas.

   DISCUSSION...Seasonably moist low-level return flow is in the
   process of veering from a southwesterly to more of a westerly
   component in the 925-850 mb layer across eastern Oklahoma through
   southern Missouri.  However, as moisture quality continues to
   increase during the next few hours, this is still forecast to lead
   to substantive destabilization, as mid-level heights gradually begin
   to fall across the southern Great Plains through Ozark Plateau
   vicinity.  Large-scale ascent and cooling aloft appear likely to
   weaken inhibition sufficiently to support increasing thunderstorm
   development in a corridor as far east as southern Illinois and
   adjacent portions of the lower Ohio Valley by 08-09Z.

   Based on forecast soundings, destabilization across much of this
   swath will remain rooted above a generally cool and stable boundary
   layer.  However, modestly steep mid-level lapse rates might
   contribute to sufficient conditional and convective instability to
   support small to marginally severe hail in widely scattered stronger
   initial cells, before convection becomes more widespread.  Storms
   capable of producing severe hail may be most concentrated (in a
   relative sense) across northeastern Oklahoma into southwestern
   Missouri and adjacent northwestern Arkansas, where surface dew
   points are increasing to around 60F.  Although destabilization may
   become rooted close to the surface across this area (in close
   proximity to the surface troughing), guidance suggests that this may
   coincide with low-level hodographs shrinking and trending more
   linear.

   ..Kerr/Smith.. 12/16/2024

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

   ATTN...WFO...LZK...SGF...TSA...

   LAT...LON   36909531 37979203 36299139 35469436 35769607 36909531