Mesoscale Discussion 0620
   NWS Storm Prediction Center Norman OK
   0144 PM CDT Sun May 17 2020

   Areas affected...Eastern/Southern IL...Western IN

   Concerning...Severe potential...Watch possible 

   Valid 171844Z - 172045Z

   Probability of Watch Issuance...60 percent

   SUMMARY...Gradually increasing thunderstorm coverage is anticipated.
   Primary severe hazard with any stronger storm is damaging wind gusts
   although a brief tornado is also possible. Trends are being
   monitored for potential watch issuance.

   DISCUSSION...Recent surface analysis places a low over far northwest
   IL. A warm front extends from this low southeastward into northern
   IN (roughly along the 65 deg F isodrosotherm) and then eastward into
   northern OH. A cold front also arcs from this low into central IL
   and then back southwestward through south-central MO. Air mass
   between these two features over eastern/southern IL and
   central/southern IN is characterized by temperatures in the upper
   60s (near the warm front) to the mid 70s (across southern IL/IN) and
   dewpoints in the low to mid 60s. Diurnal heating has been limited by
   cloud cover thus far, limiting air mass destabilization. Some
   thinning of the clouds has been noted recently in visible satellite
   imagery across southern IL. 

   The warm front is expected to continue moving gradually northward
   while the cold front sweeps eastward. Highest thunderstorm coverage
   is anticipated along the front, where low-level convergence will be
   greatest. A mostly linear storm mode is anticipated along the front,
   with damaging wind gusts as the main severe hazards. Storm
   development is also possible in warm sector, but storm strength will
   likely be tempered somewhat by the limited instability. Even with
   the low-topped nature of these storms (both over the warm sector and
   along the front), recent KLOT VAD sampled a modestly strong and
   veering low-level wind profile. The resulting long low-level
   hodograph is indicated of a kinematic environment that could support
   brief tornadoes. Convective trends across the region are being
   monitored closely for potential watch issuance.

   ..Mosier/Guyer.. 05/17/2020

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

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

   LAT...LON   41768914 41928889 41938829 41728741 41378666 40488663
               39578683 38718719 37658819 37958974 38609006 40468950
               41068927 41768914