Mesoscale Discussion 0251
   NWS Storm Prediction Center Norman OK
   0133 PM CDT Sat Mar 28 2020

   Areas affected...Parts of central/northeast Missouri into southeast
   Iowa and portions of west central Illinois

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

   Valid 281833Z - 282030Z

   Probability of Watch Issuance...80 percent

   SUMMARY...The initiation of scattered supercells appears
   increasingly probable during the next few hours.  Tornadic
   potential, including the risk for strong tornadoes, seems likely to
   increase by 4-6 PM CDT.

   DISCUSSION...Rapid deepening of the surface cyclone now centered
   over southeastern Nebraska is ongoing, with an axis of 2-4 mb
   2-hourly surface pressure falls now pivoting northeastward, to the
   northeast of the lower Missouri Valley.  To the southeast of cyclone
   center, a dryline continues to sharpen across southwestern Iowa and
   western Missouri, and may maintain identity into late afternoon,
   advancing northeastward just ahead of a surging cold front.

   Strengthening and backing (to southerly) 850 mb flow ahead of these
   boundaries is forecast to contribute to enlarging clockwise curved
   low-level hodographs by late afternoon, beneath a very strong
   (90-110 kt) 500 mb jet.  As this occurs, the environment appears
   likely to become increasingly conducive to tornadic supercells given
   sufficient boundary-layer destabilization.

   Mid/high-level cloudiness and precipitation, to the south of the
   warm front near the Missouri/Iowa border, continues to slow boundary
   layer destabilization in the warm sector.  However, a tongue of mid
   60s+ surface dew points appears to be in the process of advecting
   north of the Missouri Ozarks, ahead of the dryline, in response to
   the strong surface pressure falls.

   As a vigorous upstream mid-level trough and embedded closed low
   accelerate northeast of the central Plains, broadly anticyclonic
   mid-level flow will increasingly transition to cyclonic across the
   region through 21-23Z.  The leading edge of stronger difluence aloft
   may already be aiding convective development near the dryline and
   warm front, southeast of Shenandoah IA.  A further increase in
   discrete storm development appears possible within the next couple
   of hours, along/ahead of the dryline to the south.  Further
   development, intensification and northeastward advection of storms
   now spreading across the Missouri Ozarks also appears possible
   within the warm sector.

   Regardless, storms interacting with the warm front probably will
   pose a risk for tornadoes, while strong deep-layer wind fields and
   shear within the destabilizing open warm sector will contribute to
   fast storm motions and potential for long-lived/long track
   supercells with increasing potential to produce strong tornadoes
   across northeast Missouri into southeast Iowa and adjacent west
   central Illinois by 21-23Z.

   ..Kerr/Goss.. 03/28/2020

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

   ATTN...WFO...ILX...LSX...DVN...SGF...DMX...EAX...

   LAT...LON   40889477 41639344 41829200 41689106 40139078 38779156
               38399282 39949318 40889477