7/20/06 FCST: WI / IL / MI / IN / OH

[Robert Dewey]

Looks like things could get a little active on THU. There appears to be decent instability, especially across northern IL (MLCAPE over 4000J/KG) ... Weakening towards MI (this will depend on leftover debris). However, MI still has 2500-3000J/KG of SBCAPE with 0-3KM SRH of almost 400m2/s2. Models output decent QPF across the area as well...

 

[Jeremy Lemanski]

I think tomorrow won't be much by the looks of things. Supercells should form a large MCS tonight across Southern Minn. into Iowa and that will move ESE toward Northern Ill by morning. Clouds will limit heating and moisture transport will be disrupted. Also, the Front looks to come in a little fast.

 

[Robert Dewey]

I think tomorrow won't be much by the looks of things. Supercells should form a large MCS tonight across Southern Minn. into Iowa and that will move ESE toward Northern Ill by morning. Clouds will limit heating and moisture transport will be disrupted. Also, the Front looks to come in a little fast.
[/b]

I think the MCS is already ongoing, check out the massive bow echo across MN. That things moving at over 60MPH... I'm just wondering where it will go, and when it will get there. If sfc moisture was better across the Great Lakes region (with associated instability), I'd be inclined to say we might be looking at a long lived / large scale bow echo / derecho. My guess is that it will dive ESE towards the more unstable air / along the 1000-500mb thickness.

If we can advect at least SOME instability in here, I'm wondering if the system might continue it's ESE course and track into MI?

 

[Jeremy Lemanski]

I think the MCS is already ongoing, check out the massive bow echo across MN.


I don't know, i think the supercells that develop later on will form MCS number two and that one will screw this state up tomorrow in terms of heating and moisture transport.

Now, if this keeps clouds socked in all day and no storms form today/tonight, then tomorrow gets a whole lot more interesting since there would be sun and a SW that would bring the 70 DPs back in. Since this current system wasn't really picked up well on the models, its gonna be a wait and see type of threat.

 

[Andrew Pritchard]

I'm keeping an eye on the middle part of Illinois tomorrow afternoon. It looks like the MCS will move through the northern half of the state during the early morning towards noon. Looks like another day with strong to extreme instability over much of Illinois south of the MCS. The surface low will move into west central Illinois during the afternoon as well. While not as strong as today, it will bring an area of backed winds to the central part of the state. 0-3km srh values of 200-250 overlapping the extreme instability with about 30 kts of deep layer shear should be sufficient for a few supercells along the southern flank of the mcs, and along its ofb near the surface low in central Illinois, and into south central Illinois during the evening.

It's a tough forecast to make trying to decipher what's real and what's being caused by convective feedback, but it does look like an active day across the state with damaging winds in the morning, and more severe storms dotting the area toward evening.

 

[Jeremy Lemanski]

well, i so far there isn't anything tonight to screw the heating and moisture transport up for this area tomorrow, i hope it stays that way. APX said a 80/67 gives 1,000 ML cape tomorrow, hoping to do better then that, maybe around 85/70.

 

[Robert Dewey]

well, i so far there isn't anything tonight to screw the heating and moisture transport up for this area tomorrow, i hope it stays that way. APX said a 80/67 gives 1,000 ML cape tomorrow, hoping to do better then that, maybe around 85/70.
[/b]

I hope so too... Td's across SW lower already near 72F, with more low to mid 70's just southwest of that. I'm hoping we can hit at least 73F with the td's, and mid to upper 80's. That's obviously a dream, which would only come true if we can keep a crappy MCS from firing tonight.

That CAP tonight is incredible (thermo-nuclear is the word), but that doesn't mean elevated junk can't develop.

EDIT: Well, unfortunately I see decent returns starting to show up on the MPX radar... Latest RUC and NAM (00Z stuff) shows this activity building into a rather healthy MCS.

 

[Robert Dewey]

Well, chalk this one up as another loss. I knew things were going bad when I Seen those cells popping up across MN last night. I really don't know it that made all the difference though, wind fields aren't really that impressive - but CAPE AOA 3500J/KG can go along way [read: could have].

I'm about ready to give up ... that means not checking another forecast model until September or October (to check for those nice autumn bombs).

 

[Andrew Pritchard]

I'm still watching portions of central IL. The mcs cleared out in time for the sun to come out and heat things back up. SBCape ranges from 3000 to even 5000 j/kg across western IL per the latest spc mesoanalysis. 0-3 km srh values are as high as 400, with 200 m2/s2 values common across central IL. The mcs left an ofb draped across western Illinois and eastern Iowa. That, along with the cold front dropping in from the north could prove to be another focus for surface based thunderstorms. Convergence isnt all that amazing along the cold front, so of the two I'd watch the ofb more closely. Surface winds are backed nicely out of the se across central IL so we do have some low level turning, and deep layer shear in the range of 30-40 knots. At this point things look quiet for now, but I'll be keeping an eye on a line from Quincy to Springfield to Decatur later this afternoon into the evening.

 

[beaudodson]

Storms really struggling this evening. CAPE readings are still 4000 or so across portions of MO and IL. The sun is about to set and it appears that whatever does fire will mainly wait for dark. Will be interested in seeing whether a line can form later this evening (similiar to last nights system). Tomorrow could be a more interesting day if we don't have to deal with a lot of debris in the morning.

A lot of boundaries across Missouri and Illinois. You can watch one of those moving southward just north of St Louis at this time. Another one helped form the storms west/southwest of St Louis that briefly went severe.



Nice AE loop of that storm
http://www.usawx.com/beausstlouisanimation2.gif

The hail core associated with that storm
http://www.usawx.com/beausstlouisanimationhail.gif