7/17/07 FCST: IA / MN / WI / IL / SD

[Brian Stertz]

The latest RUC shows that there is a very nice bulls-eye on the boundary across NE Iowa later this afternoon & evening....and possibly including adjacent areas of SE Minnesota, SW Wisconsin, and extreme NW Illinois. The EHI, VGP, decently low LCLs on the boundary, and 0-6km shears of 45-55 kts. should support several tornadic supercells particularly across NE/EC Iowa. The conditions appear to be pretty ripe today for more mammoth sized hail today as well with the more intense supercells.

 

[Derek Weston]

IMO, RUC is showing today's threat as being better than yesterday, thus far.

Central IA through E. Central through NE IA into SE MN, SW Wisc and NW Ill.
(SPC mesoanalysis showing C. Iowa to be looking good right now)

The 850 flow might be a little weak up past the IA border region, though. (lower level flows a little weak in S. Iowa)

In my opinion: Waterloo Iowa looks rather ideally situated today for some strong action. The rectangular region created between Des Moines, Mason City, Dubuque and Iowa City looks to have the best combo of CAPE and shear.

 

[Andrew Pritchard]

Had I not spent all my money on chasing yesterday I'd also likely be chasing today. Looks like the same exact areas more or less that got hit yesterday. I think the shear is slightly greater today however, but not by much. I think again we'll probably see large HP supercells with very large hail, and maybe some rain hidden tornado reports primarily in the eastern 1/3rd of Iowa. After sunset the low level jet kicks in even stronger, and we should see an upscale growth into a large and intense mcs across eastern Iowa, into northwest Illinois. With strong instability remaining, and strong effective shear I think we stand a chance to see a more intense damaging wind event than last night across northwestern Illinois into central Illinois, and possibly even into western Indiana. I would not be surprised to see a few significant wind reports after sunset across that general area as the threat transforms from a large hail, to a wind threat. I'd expect the biggest damaging wind threats to carry along a line from eastern Iowa to the Quad Cities to Peoria, IL.

Only real concern with today would be the cap. It should remain fairly robust across much of Iowa for a good chunk of the afternoon. However with the intense surface heating the area is seeing right now the cap should be breached by around 5 or 6 PM.

If I were chasing today, I would have the same general target as yesterday right around Iowa City.