3/14/07 FCST: MO / IL / IN / OH / MI

I was about to give up on this potential until I saw todays SWODY 3 and the new WRF/GFS models.

Discussion: It now appears that instability may be somewhat stronger than previously anticipated. Rather strong warm air advection to take place in front of the boundary. Temps hitting near 65-70 degrees and LI's are pretty impressive.. Models vary pretty well on the amount of instability present at the time of the passage.. And this will be VITAL to the amount of severe weather. What interests me is the rather ominous wording in the SWODY 3 outlook, given the sub slight category. SPC notes the very true fact that increasing vertical shear ahead of the front could rotate updrafts.. With the greatest tornado threat over central IL. Wouldn't be surprised to SPC upgrade to a slight risk tomorrow.. Dont think that this will be any sort of big event.. But will bear watching.

http://www.weather.cod.edu/forecast/ETA/etaUS_0_mulcape_72.gif

http://wxcaster2.com/CENTRAL_ETA_SVR_CAPESRHSWEAT_72HR.gif

I will be gone all day. but I may try to post again later if time allows. If not I will be back tonight.
 
The shear is really weak on this setup. The areas of greatest instability have less than 30 knots 6km shear, which is going to inhibit organization. The elongated surface low is too weak to provide any good low level shear or backed winds. Shear is better right on the front but instability is going to be severely lacking here. Models are also showing a bit of a cap in this region too. I'm sitting this one out unless something changes. Sorry to be so negative but this setup looks very marginal.
 
Personally, im not too terribly worried about the shear. I think it should prove effecient enough for organized development, and will definitely be enhanced along the surface wave. Vertical shear should become increasingly better through the day. I agree with the SPC that a few tornados may be possible. Interesting.... The latest 12z models have shifted the area of concern slightly eastward though.

My only concern attm is moisutre and destabilization. Still 36 good hours to pick a chase target. That is if it still looks chaseworthy by then.
 
The GFS and WRF are both painting the severe event far to the north along the lakes, and more toward after dark. The models show Pwats on the high side over the entire area Wednesday-Friday, with persistent heavy precip. Could be more of a flood event 100 miles on either side of the Ohio River from Louisville to Wheeling.
 
I think Michigan should be added to the list as we're now part of the slight risk area. Looks like the better CAPE will stay south but we're still going to get around 500-750. The two main hindrances for SC development is the mid-level cap, which is forecasted to be somewhat strong, and the unidirectional shear.

I'll know by morning if I'll set up to chase this.
 
If I were going to chase today, I think I would head for the Champaign-Urbana or Danville, IL area, east into nearby portions of Indiana. Looks like some TCU starting to pop up there, and that is also the area that looks to have the best shear and instability parameters (but still marginal). Farther west and south, cloud debris from activity over southern MO and surrounding areas is spreading north and will likely limit instability. However, this looks like too marginal a situation for me to travel taht far, so I will just hang out and if anything pops closer to home, do a local chase. Right now, I don't expect much this far west/south, however.
 
Wind field gets good for some downbursts, but convergence pretty weak along the front with the best winds well south in central Indiana / Ohio... Not expecting MI to get any action. Front just passed through Lansing dropping temps back down through the fities.
 
From the looks of it SE Michigan still has a chance at some development towards the later part of the day. DPs are closing in on 60F with temps in the upper 60s. CAPE is weak but growing and we've had cloud cover all day to hinder any significant daytime heating. If something's going to pop it's going to be stictly SE Michigan and mostly just heavy rain with a chance at some hail. I don't see anything coming close to tornadic as unidirectional shear is strong and the lack of sufficient instability.
 
If I were going to chase today, I think I would head for the Champaign-Urbana or Danville, IL area, east into nearby portions of Indiana. Looks like some TCU starting to pop up there, and that is also the area that looks to have the best shear and instability parameters (but still marginal). Farther west and south, cloud debris from activity over southern MO and surrounding areas is spreading north and will likely limit instability. However, this looks like too marginal a situation for me to travel taht far, so I will just hang out and if anything pops closer to home, do a local chase. Right now, I don't expect much this far west/south, however.

I agree with you, which is why I'll be sitting here at home in Champaign. This area looks as good as any, and will have the "best" dynamics by the time the front starts pushing in. I think storms will develop anywhere from Missouri into Ohio along the front, but the best area for anything severe and even remotely tornadic (brief spin ups at best) should be in central/eastern Illinois and maybe western Indiana. I'll be heading out, but locally, and without hopes of seeing a lot.
 
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