Tonight’s severe weather expected to stay south of the Chicago Metro area

Weather Blog
 Mesoscale Discussion 1236
   NWS Storm Prediction Center Norman OK
   0535 PM CDT Wed Jul 15 2020

   Areas affected...Illinois and far eastern Missouri

   Concerning...Tornado Watch 373...374...

   Valid 152235Z - 160000Z

   The severe weather threat for Tornado Watch 373, 374 continues.

   SUMMARY...Severe weather will remain likely across WW373 and 374
   into this evening. All modes of severe weather including a few
   tornadoes will be possible. A small downstream watch may be needed
   for far eastern Illinois.

   DISCUSSION...22z surface analysis showed the center of an MCV was
   located across northwest Illinois. A broken band of storms with a
   few semi-discrete supercells were ongoing ahead of the MCV from
   north central Illinois, southwest into far eastern Missouri. These
   storms are expected to persist thanks to moist and unstable
   conditions with surface dewpoints in the low to mid 70s across much
   of Illinois. 0-1 km SRH of 150-300 J/kg, as sampled by the ILX VAD,
   supports low-level updraft rotation. Several supercells and line
   mesovortices have been observed suggesting all severe hazards,
   including a few tornadoes, remain possible. 

   There is some uncertainty on the longevity of severe convection
   across eastern portions of WW373/374. Drier surface conditions and
   weaker wind fields toward the Indiana border suggest that convection
   will gradually weaken as it encounters lesser instability and weaker
   low-level shear away from the MCV. However, a small downstream watch
   may be needed to cover any short-term threats that persist with
   storms this evening.

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