ZCZC SPCSWOMCD ALL
ACUS11 KWNS 112309 
SPC MCD 112309 
ILZ000-120045-

Mesoscale Discussion 1835
NWS Storm Prediction Center Norman OK
0609 PM CDT Mon Oct 11 2021

Areas affected...central through northeast Illinois

Concerning...Tornado Watch 521...

Valid 112309Z - 120045Z

The severe weather threat for Tornado Watch 521 continues.

SUMMARY...Threat for locally strong to severe gusts and a few brief
tornadoes will persist from central and northern IL through early
evening.

DISCUSSION...An arcing line storms with embedded bowing segments and
occasional meso-vortices continues moving northeast through central
and north central IL at 35-40 kt. The activity is moving through a
relatively narrow instability corridor with 500-1000 J/kg MLCAPE.
Despite the somewhat marginal thermodynamic environment, vertical
wind profiles continue to exhibit large low-level hodographs with
250-300 m2/s2 storm relative helicity as well as 50+ kt effective
bulk shear. The downstream environment across northeast IL will
remain favorable for occasional embedded organized structures
through early evening. Storms will eventually pose a severe threat
for the Chicago metro area near or shortly after 00Z.

..Dial.. 10/11/2021

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

ATTN...WFO...LOT...ILX...DVN...

LAT...LON   39348833 40068822 40648830 41218883 41598952 42388905
            42178750 39548763 39348833 

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