SPC MD 1810

MD 1810 CONCERNING SEVERE POTENTIAL...WATCH POSSIBLE FOR MOST OF INDIANA AND PORTIONS OF SOUTHERN ILLINOIS
MD 1810 Image


Mesoscale Discussion 1810
NWS Storm Prediction Center Norman OK
1212 PM CDT Tue Aug 20 2019

Areas affected...Most of Indiana and portions of southern Illinois

Concerning...Severe potential...Watch possible 

Valid 201712Z - 201915Z

Probability of Watch Issuance...40 percent

SUMMARY...Locally damaging winds remain possible with the
progression of an MCS southeast through the area.  A Severe
Thunderstorm Watch is possible.

DISCUSSION...A well-organized MCS with attendant MCV continues
moving southeast at 35-40 kt over Illinois with a slowly broadening
lead convective line arcing from Chicago to near St. Louis.  The
main limiting factor for a more widespread severe wind threat is
weak low-to-mid level wind shear present ahead of the MCS, which
should support a continuation of a significantly upshear-tilted
system and slowly weakening mesoscale rear inflow.  However, ample
instability owing to rich boundary-layer moisture and some daytime
heating (prior to the anvil spreading over the area), and minimal
convective inhibition, should support the continued generation of
some convection along the outflow through the afternoon.  In
addition, widely-scattered storms should continue to develop ahead
of the MCS, particularly in the vicinity of a mesoscale band of
confluence stretching northwest to southeast across southern
Indiana.  Although the MCS should continue south and eastward in a
somewhat disorganized state (compared to this morning), low-level
lapse rates will be sufficient to support locally damaging winds
with the stronger convective pulses.  The main uncertainty is
whether or not the coverage of the threat will be large enough to
warrant a Severe Thunderstorm Watch.

..Coniglio/Thompson.. 08/20/2019

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

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

LAT...LON   41198745 41458736 41658678 41638621 41318549 40588525
            39628538 38988573 38598633 38168717 37888793 37808833
            37678913 37828952 38098990 38378995 38578990 38938887
            39538786 40078755 40538748 41198745 

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