9/15/04 FCST Midwest/Great Lakes

Mar 3, 2004
Mt Prospect, IL
There is a severe weather risk over this area tomorrow. It may not be much due to warm air aloft, but with a warm humid air mass at the surface and the jet stream blowing overhead, there should be substantial lift along the cold front to at least brew a few severe storms. It appears damaging winds will be the main threat due to deep layer unidirectional shear, however SPC does include the threat of hail and/or tornadoes. Any Great Lakes chasers interested??
I will probably be out tomorrow afternoon. I am in SE wisconsin near Milwaukee. Hopefully will get to see something before years end.
I'll be keeping my eyes open to further developments and taking an opportunistic approach. Right now. the unidirectional wind field doesn't get my hopes up.
If tonight's convection is any indication of what tomorrow could be like, it could get interesting. Outflow boundaries anyone? On the other hand, there could be extensive residual cloudiness preventing too much heating. Gotta see what happens to the thunderstorms overnight as they continue to feed on this July-like airmass.
The air is already looking unstable this morning. I see ACCAS clouds filling the sky with towering Cu off to the west. The low this morning only dropped to about 70 degrees and it is on it's way up. The 100 mb CAPE is forecast to be around 500 J/kg this afternoon. LCL should be under 900 mb. LFC is about 750 mb. Looks like some deep surfaced based convection should get going this afternoon. Bring on the storms!
Dew points in 60s ok, there may be enough moisture to get interesting. Looks to me like tornado possibilities will again take a split path, one band to the south around NW IL/SW WI/E IA and the other band to the north around LaCrosse area. I'll be out later this afternoon.
SPC has scaled back TOR probabilities in IL and increased them in WI to 5% It is getting quite warm here in Dekalb. 81/66 at about noon. Lots of bright sunshine to warm us up to the initiation temperature of about 85-86 degrees. I think there is just as good a severe weather threat farther south into IL. Still a good wind damage risk of 15% into Chicago area. I am seeing towering Cu and Cb to my west. Unless the uber-cap forms, I say it won't be long now.