Storm Prediction Center Mesoscale Discussion 502

   Mesoscale Discussion 0502
   NWS Storm Prediction Center Norman OK
   0220 PM CDT Sun Apr 20 2025

   Areas affected...Eastern Missouri into western Illinois and far
   southeastern Iowa

   Concerning...Severe potential...Watch likely 

   Valid 201920Z - 202115Z

   Probability of Watch Issuance...80 percent

   SUMMARY...A tornado watch will be forthcoming for portions of
   eastern Missouri into western Illinois and far southeastern Iowa, as
   a warm frontal boundary continues to lift northward out of central
   Missouri.

   DISCUSSION...Breaks in cloud cover, along with a northward-lifting
   surface warm frontal boundary, have resulted in continued
   destabilization across eastern Missouri into western Illinois. With
   mixed-layer CAPE forecast to exceed 1000 J/kg in the presence of
   strong wind shear (and strong curvature of the low-level hodograph
   in the vicinity of the front), the tornado threat is expected to
   increase this afternoon into the evening hours. 

   Ongoing storms along the MO/KS/OK borders are forecast to continue
   north and east into the new watch area, with supercells embedded
   within a largely linear complex. Any embedded supercells (especially
   any within the vicinity of the warm front), as well as any
   pre-frontal storms, will have access to an environment characterized
   by strong low-level shear/streamwise vorticity supportive of tornado
   development. Current VAD wind profiles from KLSX show 200 m^2/s^2 of
   0-500m storm relative helicity -- nearly double what is shown in the
   current SPC Mesoanalysis. Given the environmental support for
   tornadoes, some of which may be strong, a tornado watch is
   anticipated within the next hour or two.

   ..Halbert/Goss.. 04/20/2025

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

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

   LAT...LON   41249043 41119012 40788991 40498976 39178955 38668947
               38138943 37538936 37258941 36988946 36868967 36749007
               36709052 36679128 36699176 36819216 36939224 37269227
               38759232 39489239 40199248 40619251 41139238 41309216
               41289125 41249043 

   MOST PROBABLE PEAK TORNADO INTENSITY...120-150 MPH
   MOST PROBABLE PEAK WIND GUST...65-80 MPH
   MOST PROBABLE PEAK HAIL SIZE...1.00-1.75 IN