Iowa and Northern Missouri in the Convective Crosshairs

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I had reconciled myself with the thought that this autumn’s storm season would be a no-show in the Great Lakes and Corn Belt. Leave it to the atmosphere to prove me wrong, but I’m not complaining. How’s this for a NAM forecast sounding for October 23 in Des Moines, Iowa (click on image to enlarge)?

Maybe not the sexiest hodograph, but I won’t kick it out of bed for eating crackers, and you’ve got to love that 1,811 J/kg SBCAPE. Storm-relative helicity could be better, but still, you got yer 0-2 km EHI of 2.1, yer -6.4 LI, 4 km VGP of .3, nice influx of moisture, good upper level support…what more do you want this time of year? Eggs in your beer?

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Sixty-five miles southeast of Des Moines in Moravia, the sounding for 21Z looks even better with slightly bigger CAPE, -6.8 LI, a curvier hodograph, a southwesterly H5 cruising along at a stout 50 knots, BRN of 26, and better 0-6 km shear. Bulk shear is actually a bit of a concern–the NAM sounding gives a less optimistic view of it than does the map–but we’ll see how that plays out in future runs. I have a hard time believing that shear won’t be adequate.

I’m seriously contemplating going after this scenario. And it’s just a forerunner; another, stronger system looks to be moving through the Great Lakes in the Monday/Tuesday time frame, with backing surface winds pumping a nice plume of moisture into the region.

All in all, those of us up here in the great north woods may get one or two last whacks at some decent storm chasing and maybe even a few tornadoes before the snows fly. I’m keeping a close eye on this setup and crossing my fingers.

October 22, 2010 by
Filed Under: Storm Chasing, Tornadoes, Weather Tagged With: , , , , , , , , ,

Midwest Storm Chase Shaping Up for Monday

Monday is shaping up to be one of those days that will tear me in two: the first really decent storm chasing setup in the Midwest, beautifully accessible, but my finances are too meager right now for me to do anything about it. Aaargh!

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Just look at this TwisterData 12Z NAM forecast sounding for April 5, 00Z, in extreme northeastern Missouri, up near Cantril, Iowa (click to enlarge). It’s near a nice 1 km EHI bullseye. Nice CAPE, nice veering with height, just a dab of CINH–what more could you ask for? The hodograph, not shown, curves beautifully.

However the exact mesoscale details shake out come Monday, the models have lately been coming together nicely to paint a compelling warm-front picture in southeast Iowa, northeast Missouri, and western Illinois.  Somewhere in that vicinity, tornadoes look likely. Maybe farther west, too, though capping may be an issue. Right now, though, I’m not current on the  dryline/triple point play; my attention is focused on my own back yard.

This promises to be a sweet setup for Great Lakes chasers. Maybe there’ll be some fortuitous way I can seize the opportunity, but I have an idea that I’ll be armchair chasing Monday afternoon and eating my heart out. As for Tuesday, well, there’s been talk about that, but right now I’m not as excited about it. Monday’s the day. Oh, man. So near and yet so far–gotta get to it some kinda way.

April 3, 2010 by
Filed Under: Storm Chasing, Tornadoes, Weather Tagged With: , , , , , ,