SPC AC 170100

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0800 PM CDT Tue Apr 16 2024

   Valid 170100Z - 171200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
   THE MID TO UPPER MISSISSIPPI VALLEY INTO THE SOUTHWESTERN GREAT
   LAKES AND LOWER OHIO VALLEY...

   ...SUMMARY...
   Several clusters of strong to severe storms will continue to impact
   the mid to upper Mississippi Valley this evening. The severe threat
   will affect the southwestern Great Lakes and lower Ohio Valley later
   tonight. Damaging wind gusts, isolated large hail, and a few
   tornadoes will be possible.

   ...Mid to Upper Mississippi Valley/Southwestern Great Lakes/Lower
   Ohio Valley...
   An upper-level low is evident on water vapor imagery over the mid
   Missouri Valley, with an associated 60 to 80 knot mid-level jet
   located in the mid Mississippi Valley. At the surface, a 989 mb low
   is located in far northwest Iowa, with a corridor of maximized
   low-level moisture (surface dewpoints in the 60s F) in the mid to
   upper Mississippi Valley. A line of strong to severe thunderstorms
   is ongoing along a zone of low-level convergence from northwest
   Illinois into southern Wisconsin. This line will likely be
   maintained, moving east-northeastward to the western shore of Lake
   Michigan by late this evening. Ahead of the line, the RAP has MLCAPE
   in the 1000 to 1500 J/kg range. WSR-88D VWPs in central and northern
   Illinois have 0-6 km shear around 60 knots suggesting the severe
   threat will continue this evening. Wind damage will be likely with
   the more intense parts of the line, especially with the faster
   moving bowing segments. WSR-88D VWPs across central and northern
   Illinois have 0-3 storm-relative helicity generally in the 500 to
   550 m2/s2 range. This will likely continue to support an isolated
   tornado threat with rotating storms that remain somewhat discrete,
   or with circulations within the line itself. Isolated large hail
   could also accompany the stronger rotating cells.

   Further south into the mid Mississippi Valley, the RAP is analyzing
   MLCAPE in the 1200 to 1500 J/kg range across much of eastern
   Missouri and Arkansas. The instability combined with 0-6 km shear in
   the 60 to 75 knot range will likely support a severe threat this
   evening. However, large-scale ascent is weaker this far south
   suggesting that storm coverage will be isolated. Any cell that can
   intensify near the instability axis this evening, could be
   associated with wind damage and hail. A marginal tornado threat will
   also be possible.

   ..Broyles.. 04/17/2024

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