2012-08-09 FCST: MI/IN/IL/Lake Michigan

[Skip Talbot]

Kind of a modest setup in the works here, especially if you're going for tubes, but I see a play for local Midwest chasers if you've got nothing going on tomorrow. NAM has a positively tilted trough and shortwave ejecting across northern IL into northern IN/southern MI Thursday evening. The bulk of the upper level energy looks to lag behind the warm sector during the most favorable hours, but some of it is nosing in there and should give us some lift and shear to sustain some severe storms. At the surface, a sloppy elongated area of low pressure is nosing into Michigan with a warm front draped across the IN/MI border. A plume of rich moisture (dews approaching 70) and moderate instability (1500-3000) is forecast across the warm sector bumping into that warm front. Directional shear is enhanced along this warm front, with nice helicity values north of the front, and more than enough instability for supercells south of the front. There's probably a sweet spot right between the two. Unfortunately, there looks to be ongoing convection across the entire warm sector all day long due to lack of capping and other sources of lift. That's going to throw a wrench in getting any decent instability or discrete activity and may make for a pretty crappy chase. If there is enough of a gap in the junkvection, I could see a supercell or even a tornado in the southern MI, northern IN region, and otherwise just some ugly MCS action elsewhere across the warm sector.

Also of interest is a waterspout setup across Lake Michigan. A closed 500 mb low is forecast to move across Michigan overnight Thursday into Friday morning. With it, temperature aloft look to be quite cold. 15C spreads between 850 mb and the lake surface make for very favorable low level lapse rates, and with deep convection developing under that closed low, the environment looks primed for spouts. Decent surface based cape is being plotted over the lake on Thursday afternoon and evening. Tall thunderstorms have a shot at producing spouts at the same time as the potential supercell chase noted above. I'm a little more interested in Friday morning, when temps aloft look coldest and lapse rates the steepest over the unusually warm lake waters. A northerly wind should push cells in a favorable parallel direction to the early AM land breeze, letting any updrafts tracking along the boundary tap the favorable vorticity. Hopefully the crapvection and rain from earlier Thursday activity doesn't cool the lake surface off too much.

I'll probably start off on the warmfront in northern IN/southern MI looking for supercells and if that busts due to junk in the warm sector, I'll quickly head over to the lakeshore and see if I can pick up a spout Thursday evening into Friday morning on Lake Michigan. A pretty modest tornado chase, but I had an absolute blast last September on my first waterspout chase, bagging two and enjoying the much more relaxed pace of watching convection lakeside with friends. I've been looking for another chance ever since, and tomorrow (into Friday) might be it.

 

[Bob Hartig]

A quick-n-dirty of the 18Z NAMM paints a nice EHI max (both 1 and 3 km) between Ft. Wayne and Muncie, IN, at 21Z--well south of the WF, but a glance at the forecast sounding shows a surprisingly nice hodo overlaying a blob of enhanced CAPE. However, the mid-level moisture profiles suck throughout the region--that old crapvection story you've amentioned. That's how it is in these parts: there's always something to squelch a potentially decent scenario. Still, you never know. Moths are flying from my wallet right now, but if a check comes in the mail tomorrow, I may head out. It's been way too long, and with a warm front to play with...

 

[Connor King]

Hey gentleman. I agree with the both of yall. I am not overly impressed with the strength of the mid and upper level winds however the directional shear along and just south of the warm front where that 0-1 EHI max is looks very interesting. I am curious to see how this CRAPvection tonight is going to pan out because so far, it has seemed very spotty. It will most likely ramp up though in the overnight hours with the theta-e focused in se ia ne mo. If even a small area can clear thought late tomorrow afternoon, I can definitely see a couple of brief tornadic supercells evolving in NC indiana. This will obviously be a nowcast situation, but I'll make up my mind in the early AM. Might head over that way from Peoria, IL after work. I like 21z in NC indiana right now along and just south of the northward retreating wf near Kokomo. Something to also keep in mind is that early morning convection could hamper the northward progression of the front.