Clearpost.online It's your post, so post it!

Mesoscale Discussion 0847
NWS Storm Prediction Center Norman OK
0710 PM CDT Fri May 20 2022

Areas affected...Northeast Missouri through northeast Illinois

Concerning...Severe potential...Watch unlikely 

Valid 210010Z - 210215Z

Probability of Watch Issuance...20 percent

SUMMARY...Isolated to scattered thunderstorms developing along and
behind a cold front may be capable of strong winds and severe hail.
However, the coverage of this threat appears limited, and watch
issuance is not anticipated.

DISCUSSION...A cold front continues to meander to the southeast
across IL and MO per recent surface observations and GOES visible
imagery. RAP mesoanalysis data shows the environment along and ahead
of the cold front remains largely capped, but features 2000-3000
J/kg MUCAPE due to steep mid-level lapse rates between 700-500 mb.
Despite recent analyses, recent ACARs soundings from Chicago, IL and
St. Louis, MO show weaker capping, and a few weak thunderstorms and
convective showers have initiated in both regions. This trend
suggests that the cap is breakable given sufficient forcing for
ascent along and/or behind the cold front. Lift along the frontal
zone may increase over the next 1-2 hours as broad ascent associated
with the upper-level trough (currently displaced to the west over
the Plains based on recent water-vapor imagery) overspreads the
Midwest. This may support isolated to scattered thunderstorm
development along and behind the front in the co*ing hours. This
convection may beco*e elevated in nature, but 30-45 knots of
effective bulk shear should allow for sufficient storm organization
to support a severe hail risk with sporadic strong/locally damaging
winds. Overall, the coverage of thunderstorms remains uncertain
given the heterogeneity in the regional cap strength, which
precludes watch issuance at this time.

..Moore/Guyer.. 05/21/2022

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

ATTN...WFO...LOT...ILX...MKX...LSX...DVN...EAX...

LAT...LON   39649272 40469200 41399058 42338905 42698774 42298769
            42048749 41798741 41798698 41268706 40758751 40138802
            39608881 39248950 38879041 38709123 38679176 38719216
            38839240 39649272