Mesoscale Discussion 0171
   NWS Storm Prediction Center Norman OK
   0231 PM CDT Thu Mar 12 2020

   Areas affected...Portions of southeast MO and northern AR

   Concerning...Severe potential...Tornado Watch likely 

   Valid 121931Z - 122100Z

   Probability of Watch Issuance...80 percent

   SUMMARY...Thunderstorms are expected to develop over the area and
   will be capable of severe hail, damaging winds, and a few tornadoes.
   A Tornado Watch is likely in the next 1-2 hours.

   DISCUSSION...Strong forcing for ascent associated with a mid-level
   speed max and a cold front will contribute to thunderstorm
   development over the MCD area in the next 1-2 hours. Storms are
   expected to develop first over southeast MO, then southwestward
   along/ahead of the cold front into northern AR.

   The airmass over southeast MO has been slow to destabilize because
   of abundant clouds, but temperatures warming into the mid 60s to low
   70s near the AR/MO border will quickly advect northward to near
   Farmington prior to storms developing. Steep mid-level lapse rates
   of 8.5 C/km sampled by the 18z SGF sounding, dewpoints in the low
   60s, and continued heating will contribute to a corridor of
   1000-1500 MLCAPE along/ahead of the front. Supercell modes will be
   supported by effective shear magnitudes of 50-60 kt, favorable
   angles between the deep-layer shear and the front, and storm speeds
   that will be fast enough to remain ahead of the front. Although
   surface winds have veered to south-southwesterly, storm motions
   forecast to be 270-290 deg and strong 850-700-mb wind speeds should
   still result in 0-1-km SRH of 200-300 m2/s2 over the area,
   contributing to some tornado potential in the evening. Given the
   steep lapse rates and 50-kt winds in the 850-700-mb layer, severe
   hail and damaging wind gusts are also possible. A tornado Watch is
   likely to be issued.

   ..Coniglio/Hart.. 03/12/2020

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

   ATTN...WFO...PAH...MEG...LSX...LZK...SGF...TSA...

   LAT...LON   37889153 38069065 38059020 37928971 37108896 36408910
               35628997 35399067 35219108 35229148 35109250 35659338
               36499323 37039282 37749197 37889153