ZCZC SPCSWOMCD ALL
ACUS11 KWNS 150215 
SPC MCD 150215 
WIZ000-ILZ000-IAZ000-MNZ000-150345-

Mesoscale Discussion 1290
NWS Storm Prediction Center Norman OK
0915 PM CDT Wed Jul 14 2021

Areas affected...Eastern IA...Southern WI...Northwest IL

Concerning...Tornado Watch 379...

Valid 150215Z - 150345Z

The severe weather threat for Tornado Watch 379 continues.

SUMMARY...Severe threat will gradually shift southeast across ww379
this evening.

DISCUSSION...LLJ has strengthened considerably across eastern IA
into southeastern WI this evening, where 40kt is currently observed
at 1km AGL. This has aided the northward advancement of the surface
front  which is now draped from Lake County IL-north of RYV-north of
MSN. Overall, convective trends have become more multi-clustered
with an expanding corridor of thunderstorms extending
southwest-northeast along the LLJ axis. A few supercells remain
along the southwestern flank of this activity, especially just north
of Cedar Rapids. This southern activity remains concentrated in the
greater buoyancy air mass, and latest diagnostic data suggests the
immediate downstream environment remains favorable for surface-based
supercells (temperatures holding near 80F at DVN). Latest trends
suggest the SW/NE-oriented band of storms will gradually sag
southeast across the remainder of ww379 later this evening,
eventually spreading across the remainder of northern IL later
tonight as LLJ translates downstream. Greatest short-term severe
threat appears to be in the CID-DBQ corridor where surface-based
supercells continue.

..Darrow.. 07/15/2021

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

ATTN...WFO...LOT...MKX...DVN...ARX...

LAT...LON   41749171 43469172 43628902 41908901 41749171 

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