9/19/05 NOW: MI/IN/IL

[nickgrillo]

SPC just issued a blue box...

Inhibitation is slowly weakening invof the warm front located across western IN - with a very moist and unstable boundary layer in place. Strong southwesterly SFC winds and widespread insolation has aided to the development of strong SFC-based instability ranging between 2000-3000J/KG along the IN/IL border - with 1000J/KG creeping into southwest MI. Low-level shear is substantially stronger near the warm front (350-500M2/S2 0-1KM SRH) along with 50KNT-60KNT deep-layer shear which could enhance the threat for a couple isolated tornadoes / supercells in northeast IL/northwest IN within the next few hours.

 

[Andrew Khan]

Huge storms coming across the IL area as of 10-20 minutes ago. This storm is giving off an impressive outflow boundary into central IL, and I would assume, storms will be developing along this. I think it's safe to assume that western and central IL, are getting hail at this time. There is also a meso rotation, about 3.5 NM in size, in the lower severe warned cell. Tornado Warning JUST issued for IL.

 

[Andrew Khan]

There are now four meso rings out for the severe warned cell, greatest rotation still being 3.8 nm in diameter. Rotation is very obvious in the southern part of this cell, and there are about 4 Hail reports, all being from Trained Spottersm greatest hail size being, 1.00 in.

 

[nickgrillo]

The storms that are developing and moving over the warm front ( http://www.crh.noaa.gov/radar/images/DS.p1...kiwx/latest.gif ) probably have the greatest risk at producing tornadoes right now...

Let's see how they mature...

 

[Andrew Khan]

Nick, why do you thin those have the greatest risk? Are you still expecting anything in MI?

 

[Robert Dewey]

I'm having serious doubts about convective chances here in MI. Unless some towers blow up from the Cu field over SE WI, I would have to say our chances are rather slim.

SPC does show some decent MLCAPE advecting into the region with significant shear, and there is a band of SFC moisture convergence developing across SE WI, and this is on the west side of the 700MB thermal axis... So all hope isn't lost just yet.

 

[nickgrillo]

Originally posted by rdewey
I'm having serious doubts about convective chances here in MI. Unless some towers blow up from the Cu field over SE WI, I would have to say our chances are rather slim.

SPC does show some decent MLCAPE advecting into the region with significant shear, and there is a band of SFC moisture convergence developing across SE WI, and this is on the west side of the 700MB thermal axis... So all hope isn't lost just yet.

I'll tend to agree with most of your thoughts there...

I still think MI could get a few storms to pop later this evening (the RUC shows some precip breaking out by 0Z)... SPC just released an MD on MI discussing potential later: http://www.spc.noaa.gov/products/md/md2235.html

 

[David Draun]

I think Nick Grillo hit his forecast pretty good. The latest SPC MD threatens a WW for all of Lower Michigan. Looks like the storms are over for Chicago though. The storms to the south will most likely inhibit development here. It probably would have been great too. It's clear, warm, and humid here. However the front is still to the west. Mesoanalysis shows MLCAPE is still near 3000 J/kg. There is a line of Cu along the coldfront, as the visible satellite imagery displays

 

[nickgrillo]

The warm front is now pressing into southwest MI - with the cold front pushing across the lake...

It's already 6 PM, and SFC-based instability is still only about 1000-2000J/KG across most of southwest/southcentral Michigan... However, MUCAPE is a solid >2500J/KG across that area - with Td's ranging from 62-70F invof the warm front. There is some good SFC moisture convergance developing along the MI/IN border. It could always pull the 5/6/04 type thing... With convection exploding all over the MI/IN border region shortly afterdark, so I wouldn't let my guard down with this type of a setup.

I really wish we'd see some stronger instability advecting in...

I know this sounds ridiculous... But, if nothing happens closer to here - and the convection across IN remains strong (RUC/NAM brings in strong instability across ne IN/nw OH after 0Z) then I'll shoot down I-75 to shoot some lightning :lol:

 

[Andrew Khan]

TVS just tripped in the cell in IL. I think there is still a threat for supercells across the MI region, mainly the west side, however. I think that there could also be an isolated tornado or two in western MI, given the shear, helicity, LCL values. Mesoanalysis shows SBCAPE in MI of 3000 J/KG.

 

[Robert Dewey]

The cold front is clearly visible on the VIS imagery across SE WI. It's pretty much a solid band of Cu, which has been getting somewhat broader/more convective looking. I doubt much initiation will occur over Lake MI, where SBCAPES drop off significantly, but the western side of MI is prime. Even with initiation, though... My main concern is that shear (70KNTS of it in the 0-6KM layer) will simply be too strong.

 

[Andrew Khan]

Two tornado warnings have just been issued for the cell in NE IL. Rotation is still very strong in this cell, and has a meso on it. Have there been any confirmed touch downs today? Rdewey, where do you get the VIS images?

 

[nickgrillo]

Originally posted by Andrew Khan
Two tornado warnings have just been issued for the cell in NE IL. Rotation is still very strong in this cell, and has a meso on it. Have there been any confirmed touch downs today? Rdewey, where do you get the VIS images?

Rob is likely using the GEMPAK software to obtain the VIS imagery... Yet, you can get simuler images right here: http://www.rap.ucar.edu/weather/satellite/...e=-1&duration=0

 

[Andrew Khan]

He is using the link you just posted. I recently recieved a PM from him. Thank you. The cell in IL, look to begin breaking away from the cell entering IN.

 

[Andrew Khan]

There is one warning still in IL, and one was just issued for MO. There WAS a confirmed touch down in extreme west central IL, damaging one structure.