5/15/07 FCST: MI/IN/IL/OH/KY

[rdale]

All things coming together for a nice squall line ahead of a cold front moving through the Great Lakes on Tuesday. NAM/GEM were first with holding off fropa a little more, now all models pretty much warming up the region through the day with the front sliding through MI/IL by 00Z. Even MLCAPE is > 2000, there's not much directional shear but plenty of strong winds throughout the profile.

 

[Robert Dewey]

I agree... The 12Z and 18Z NAM are looking pretty favorable for squall line development. Nice Td pooling - mid-upper 60's on NAM - combined with some SFC heating should provide for some decent instability. Wind fields are looking pretty nice as well, with a 500MB jet organizing overhead. VV fields are looking pretty explosive from mid MI southward, with a blowup of QPF... With the parameters in place, this most likely suggests a lengthy and quite intense squall line.

We'll have to see what happens on the next several model runs.

 

[Brandon Sullivan]

Yup. Nice squall line setup looks to be coming. Timing looks pretty favorable attm. Nice cape, just really a lack of any shear for any rotating updrafts..

 

[Marcus Opitz]

Target:

Maybee Southern Indiana.

Models (eta) shows small tounge of relativley richer dewpoints and CAPE near the Ohio river. The upper winds look week and unidirectional from what I can see...I will toy with the idea of going out there as I am only 1-2 hours from here. Does anybody know what the chase terrain is like??? I will check things tommarow to see if it is justified to send more of my gas money to the oil cartels, LOL. I will be in a Black lexus if anybody is out there.

 

[Andrew Pritchard]

I kind of like the setup tomorrow afternoon and evening. Maybe it's because I haven't chased since Nickerson...

Either way, it looks fairly local so I'll hang around home most of the day and see what unfolds in real-time, but based on the models which have been almost totally consistant in their placement of things (but have actually increased the shear) I will likely head closer to the Illinois and Indiana border, and maybe slightly further east based on where initiation will occur. If we can get an outflow boundary to push ahead of the actual cold front we may see a better chance at supercellular structures and a tornado or two. Otherwise, if things go along the cold front we'll likely see an intense squall line. While I'll take any convection, I'd rather the first scenario play out and we get a couple storms ahead of the strong forcing of the front. Instability will be moderate, and helicity values ahead of the front push 250 in central Indiana by 0z. There isn't a ton of veering between 500 and 850mb but there is some, and speed shear is not an issue with streaks of 40-60 knots at each.

As of now somewhere in the Danville, IL - Crawfordsville, IN and Lafeyette, IN area looks like a good starting point.

 

[Jeremy Lemanski]

It would be nice to get a decent SVR threat, even if it is only a squall line as long as it offers some photo ops.

However, I'm worried, at least my area since i'm not willing to drive for such a setup, that there will be morning rain/thunder around, that will limit heating and thus kill any threat of storms firing on the cold front.

I do think southern mich into ohio and indiana should see a nice wind event tomorrow with good cape and dry adiabatic laspe rates among other factors.

 

[John Bowles]

Target:

Maybee Southern Indiana.

Models (eta) shows small tounge of relativley richer dewpoints and CAPE near the Ohio river. The upper winds look week and unidirectional from what I can see...I will toy with the idea of going out there as I am only 1-2 hours from here. Does anybody know what the chase terrain is like??? I will check things tommarow to see if it is justified to send more of my gas money to the oil cartels, LOL. I will be in a Black lexus if anybody is out there.

Aside from the occasional hill with a decent horizon, the terrain here is horrible. You'll be lucky to even see an occasional glimpse of a clear horizon.

I live in Southern Indiana, so I will be spotting - aka looking out my window.

 

[Marcus Opitz]

Thanks John,
I may head out west to the IL border just north of I-64, But I figured that was the case since I last flew over it from Chicago to Louisville. Looks like pretty country though....I will see how things play out early in the morning....

 

[Johnathan Brouwer]

I stay away from southern Indiana...its beautiful but not for chasing! Too many hills...its like southern Missouri...

Pritchard has a good idea, stay a bit more north and wait and see...

 

[Andrew Pritchard]

Well, looks like about the same thing as earlier this morning. Looks like it slowed down a little bit on this run though so I may be able to stay even closer to home. Looks like maybe two rounds, one possibly being a little ahead of the cold front which would lead to a little better chance at more discrete convection, though it would probably go linear as well. Then of course the solid line of convection along the cold front. Either way, after the spring Illinois has seen, I'm ready for dark clouds and lightning bolts close to home so I'm willing to settle tomorrow. If all else fails I'll just core punch the squall line.

Target still looks like somewhere in this area, probably on the Illinois side of the border now based on tonite's model run. I like my hometown of Champaign for a target.

On the southern Indiana target... I'll second or third or fourth the "stay away" suggestion. It's as bad an area you'll find. Illinois near Interstate 64 is okay, but any further south into the southern tip and you are in the woods. I don't think things look as good down there anyway, the speed shear really drops off a lot south of Interstate 70. If you get too close to the border down there you'll run into trouble with the Wabash River as well.

 

[Robert Dewey]

However, I'm worried, at least my area since i'm not willing to drive for such a setup, that there will be morning rain/thunder around, that will limit heating and thus kill any threat of storms firing on the cold front.

The 03Z RUC dries out the mid levels nicely, and the IR loop shows the higher cloud tops thinning out. While it probably won't be mostly sunny, I could envision several breaks through the day leading to temps of 80-85F.

I've run some of the data through BUFKIT [DTX sounding], and the storm mode is supercellular/multicellular hybrid. Shear is pretty good, with 0-2km shear running at 10-20m/s, with 0-6km shear running at 20-30m/s. Directional shear is lacking, but the speed shear suggests bow echoes. The sounding also shows a nice "inverted-v" with dry air aloft, leading me to believe that wind gusts could be quite strong in some of the storms.

Depending on the degree of forcing, this could actually end up being a pretty significant squall line event if instability can become strong enough. The shear values are strong enough to support significant squall line development when combined with the CAPE and DCAPE (as shown via an study written by Doswell/Evans regarding derechos and bow echoes)... The only question is forcing. If the NAM is correct in showing "off-the-charts" forcing in the low/mid levels, then I would say we're looking at a pretty sizeable event from MI southward.

Any other thoughts?

 

[rdale]

I think these setups call for development of a model that only does MCS's and can be run like the hurricane model on-call ;> As we've seen, no model has any idea what is really happening over the past 24 hours. So in general, it looks like a nice squall line setup is in place over MI/IN/OH later today. Still some dry air overhead in MI but don't expect that to last long. Good news is that plenty of sunshine in place already and nothing interrupting a good warmup today. So no big changes on my forecast, I'll probably drift around Marshall MI after lunch.

 

[Eric Graham]

I like the setup for today, even though it looks more of a squall line event. Plus its close since I'm up here in Lafayette, IN. So I'm going to chill and see what happens this afternoon. Be safe for those who venture out today and happy chasing.

 

[Brandon Sullivan]

I will be looking for development along the front. If I can get out of town before things get past me here, I will probably go into central IL. Just watching the vis sat and hoping the stuff in NE mo dies out for some nice insolation.

 

[Jim Hunt]

Well, 15 hours of no Internet and I see things have not changed much in the forecast for today. I will remain close to Howard County/Home and hope things work out right for some good photogrpahy. I hope out no hope for any tornadoes.