2015 05-17 EVENT: MN/WI/IA/IL/MO

[chrisbray]

I think Sunday has some real potential despite just a Day 2 slight at this point. I personally am busy until the evening so I won't be able to chase until 8pm or so, but I am at least hoping for some nice evening/night storms in central IL.

Best area might be western Wisconsin as the surface low sits over the Mn/Dakotas border and the winds are fairly backed. A line of 2000-3000 cape should form along the Mississippi River area combined with 40-55 kts shear.

Here is some 1km EHI

Sig Tor

Finally, NAM4KM shows a nice broken arc of storms for tomorrow

I have never chased in Wisconsin but I have to imagine it's pretty tree-filled from what I have seen of the state. Hoping there are a few storms that manage to go up in IL.

 

[Andy Wehrle]

Yeah, if that EHI bullseye remains consistent, looks like I'm headed up to somewhere around Sparta or Black River Falls. Will be watching trends closely tomorrow AM.

 

[kevin-palmer]

I will probably be chasing close to home tomorrow. Nearly all the ingredients are there to get some nice storms. But the dry layer of air at 500mb is concerning. This is a forecast sounding for the Galesburg, IL area (red bullseye on the above SigTor map)

Hopefully it's not quite that bad.

 

[Caleb Grunzke]

Debating where to go... The best chance for tornadoes is western/central Wisconsin but that has terrible terrain. So many hills and trees that seeing something will be nearly impossible. I'm thinking extreme southwestern Wisconsin as it still looks pretty decent according to both NAMs. The GFS doesn't look too terrible either... Storms will track northeast and hopefully stay in more favorable terrain. Below is a sounding from Dubuque, IA around the time of initiation.

 

[kevin-palmer]

Yesterday was a big cap bust. The instability was also a lot weaker than the models previously forecasted. There was one somewhat strong cell I was on that formed in Illinois and moved on to Milwaukee. But it couldn't quite tap into the wind shear. A line of storms tried to form in Iowa but they just couldn't break through the cap. All together there were only 3 severe reports in the Upper Midwest (all wind).

But it's hard to be too disappointed on a day that ended with this beautiful show of crepuscular rays over the Mississippi:

 

[Todd Lemery]

This isn't much of a report, but I was out on, as far as I know, the only tornado warned cell in the state of Wisconsin near Shawano and watched as it disappeared from the radar screen in less than an hour. I wish I could say that I ended up seeing some nice structure or something, but the truth is the only things I saw were hills and trees. All chases can't be so exciting that you hyperventilate and blow snot all over your windshield, but this one really sucked. I'm oddly especially excited about my next chase chance

 

[chrisbray]

I don't think it was a CAP issue honestly, I didn't see any CAP in place throughout the day on mesoanalysis. I thought it was poor midlevel lapse rates and lack of surface convergence.

 

[Nick L]

I second the poor midlevel lapse rates being a big reason. This was evident from what I saw in the SPC mesoanalysis, and I also read references about there being an elevated warm layer in the NWS forecast discussions. To my inexperienced eye, that's what I observed in the field. We were sitting near Monroe, WI and watched 5-6 cells fire within 5-10 miles of us. Every one of them reached a certain height, then couldn't go any higher as they (in my judgment) hit the warm layer.

 

[chrisbray]

Side note, anyone know why the images I copied didn't stay static? looks like they changed as the model runs changed, but I thought I copied just the image from COD site. hmmm