Storm Prediction Center Mesoscale Discussion 344

   Mesoscale Discussion 0344
   NWS Storm Prediction Center Norman OK
   0459 PM CDT Fri Apr 03 2026

   Areas affected...Central portions of Illinois into central and
   northwest Indiana

   Concerning...Severe potential...Watch possible 

   Valid 032159Z - 040000Z

   Probability of Watch Issuance...60 percent

   SUMMARY...The severe threat may increase into the evening hours,
   though the overall intensity and coverage of storms remains
   uncertain at the moment.

   DISCUSSION...Multicells and transient supercells persist along an
   east-to-west oriented baroclinic zone across central IL/IN. These
   storms are developing amid a moist boundary layer, characterized by
   upper 60s F dewpoints amid small T/Td spreads, with over 1500 J/kg
   MLCAPE present. The upper trough is currently displaced relatively
   far to the west, so shorter term forcing mechanisms are
   predominantly from stronger surface heating, and the ILX/IND VADs
   currently depict short and modestly curved hodographs. The current
   thinking is that storms should remain at their current degree of
   organization and intensity for at least the next couple of hours.
   Transient circulations potentially supporting isolated, brief
   tornadoes is the most immediate threat. 

   A few hours from now, into the evening hours, the gradual approach
   of the upper trough will support a substantial strengthening of the
   850 mb flow (i.e. southerly low-level jet), especially in the 00-06Z
   time frame. Should discrete, surface based storms persist in this
   time frame, it is plausible that appreciable strengthening and
   organization of supercell structures with sustained low-level
   mesocyclones may be achieved. Such storms may pose a locally greater
   tornado threat in addition to severe wind/hail. However, such a
   threat is dependent on storms remaining surface based, with boundary
   layer stabilization only gradually taking place. As such,
   uncertainty remains. However, convective trends will continue to be
   monitored through the evening hours as the low-level jet
   intensifies.

   ..Squitieri/Smith.. 04/03/2026

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

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

   LAT...LON   41219007 41558879 41278654 40818576 40368573 39968598
               39798676 39768817 39708945 39729011 39979053 40909034
               41219007 

   MOST PROBABLE PEAK TORNADO INTENSITY...85-115 MPH
   MOST PROBABLE PEAK WIND GUST...55-70 MPH
   MOST PROBABLE PEAK HAIL SIZE...1.00-1.75 IN