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