Storm Prediction Center Mesoscale Discussion 905

   Mesoscale Discussion 0905
   NWS Storm Prediction Center Norman OK
   0136 PM CDT Tue May 20 2025

   Areas affected...much of central Illinois and adjacent west central
   Indiana

   Concerning...Severe potential...Watch likely 

   Valid 201836Z - 202030Z

   Probability of Watch Issuance...95 percent

   SUMMARY...Thunderstorm development will continue to gradually
   intensify through 2-4 PM CDT, posing increasing risk for severe
   weather.

   DISCUSSION...Low-level convergence and boundary-layer
   destabilization is becoming maximized across much of central
   Illinois, within the warm sector to the southeast of the primary
   surface low center now over southeastern Iowa.  This will continue
   to be aided by mid-level cooling and forcing for ascent associated
   with a still well-defined cyclonic vorticity center to the
   west-northwest of Quincy IL, which is forecast to continue a slow
   northeastward and eastward migration across the Midwest through late
   afternoon. 

   Thermodynamic profiles, particularly centered across and southeast
   of the Springfield area, appear characterized by rather steep
   lower/mid-tropospheric lapse rates, with mixed-layer CAPE increasing
   in excess of 1000 J/kg. As residual inhibition associated with the
   remnants of elevated mixed-layer air continues to erode, the
   environment is becoming supportive of organized convection
   near/beneath the exit region of a strong mid/upper jet.  This may
   include discrete a few discrete supercells and perhaps an organizing
   cluster with potential to produce severe hail and damaging wind
   gusts.  

   Modest clockwise-curved low-level hodographs may also support a risk
   for tornadoes, particularly with the more discrete storms.

   ..Kerr/Hart.. 05/20/2025

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

   ATTN...WFO...IND...LOT...ILX...LSX...DVN...

   LAT...LON   41188923 40728835 38858721 38988952 39868947 40358973
               41188923 

   MOST PROBABLE PEAK TORNADO INTENSITY...100-130 MPH
   MOST PROBABLE PEAK WIND GUST...55-70 MPH