Severe storm potential SW of Chicago area this morning/early afternoon

Mesoscale Discussion 1831
   NWS Storm Prediction Center Norman OK
   0906 AM CDT Mon Oct 11 2021

   Areas affected...eastern MO...western and central IL

   Concerning...Severe potential...Watch possible 

   Valid 111406Z - 111630Z

   Probability of Watch Issuance...60 percent

   SUMMARY...Trends will be monitored this morning for surface-based
   thunderstorm development.  The initial area of concern will be over
   central MO and areas northeastward towards the MS River.  A tornado
   watch will likely be needed by midday for portions of eastern MO
   into western IL.  It is uncertain whether surface-based storms and a
   subsequent tornado risk will develop as far north as extreme eastern

   DISCUSSION...Visible-satellite imagery shows a compact/intense
   mid-level shortwave trough over the lower MO Valley.  Weak
   convection has been maintained this morning within the warm conveyer
   belt from southeast MO through the Saint Louis area and into western
   IL.  A surface trough/windshift is analyzed this morning arcing from
   near the low through central and south-central MO.  A small area of
   cloud breaks is noted in visible-satellite imagery over central MO
   where forcing is maximized and over the location of greatest concern
   this morning.

   Model forecast soundings show gradual destabilization this morning
   into the midday hours as temperatures slowly rise into the lower 70s
   with a moist boundary layer.  Very strong low-level flow noted at
   the Saint Louis 88D VAD is resulting in a large low-level hodograph
   (400+ m2/s2 0-1 km SRH).  Once sufficiently strong updrafts can
   develop/persist, a severe risk will likely ensue with an isolated
   risk for tornadoes and damaging winds being the primary concerns.

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