SPC 0100Z Day 1 Outlook
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
