07/13/04 NOW: MIDWEST/GREAT LAKES/OHIO VALLEY

So far this is the only game in town. Nothing else of interest going on yet. The 5500 SBCAPE bullseye is over southeast IA but it's still very capped there.

I've noticed a weak appendage on the west side of the NW IL supercell.
 
Two watches posted

We have two watches posted this late a.m. today. NWS has issued a TORN watch for Northern half of IL and a SWW for the Upper Lake Michigan area between Wisconsin and Michigan.

NWS is showing a nice storm cell moving E-SE between Freeport and Sterling, IL. Looks like it may brush close to Chicago, Joliet and Gary if it holds its course.

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looks like that cell has developed a meso per the latest velocity imagery and as said before looks to be developing a hook...expect a tornado warning any minute now...Northern IL, look out!
 
The way the weather has been this year, I wouldn't be surprised a bit if that storm created a tornado or two near Chicago. Here in Madison it is expected to hit 87, before the storms hit in the afternoon. The atmosphere has a full tank of gas to run on and this day is just starting.

:shock:
 
"looks to be developing a hook"

Only about 1/3rd - 50% at best of hook echoes result in a tornado - you need to be doing a mesoanalysis to find any sort of surface boundary to kick it into TOR mode unless the meso is REALLY turning.

- Rob
 
"looks to be developing a hook"

Only about 1/3rd - 50% at best of hook echoes result in a tornado - you need to be doing a mesoanalysis to find any sort of surface boundary to kick it into TOR mode unless the meso is REALLY turning.

- Rob

ah, well, if that's the case, then it might not produce a tornado. I just looked over the SPC's meso analysis for that region and that cell appears to be moving out of favorable sheer and convergence, so perhaps no tornadoes yet. :oops:
 
"looks to be developing a hook"

Only about 1/3rd - 50% at best of hook echoes result in a tornado - you need to be doing a mesoanalysis to find any sort of surface boundary to kick it into TOR mode unless the meso is REALLY turning.

- Rob

ah, well, if that's the case, then it might not produce a tornado. I just looked over the SPC's meso analysis for that region and that cell appears to be moving out of favorable sheer and convergence, so perhaps no tornadoes yet. :oops:

I would really be concerned with the damaging wind threat later today, maybe a couple isolated tornadoes at best, but the real threat will be widespread damaging winds. At least thats how it looks now...
 
WOW!!

According to the SPC, cape has reached 7000 just southwest of the Quad Cities. LI are now down to -14 as well! *edit*:Dewpoints have pooled to near and just above 80 degrees right along the Mississippi River!!! Wow!!

New more agressive cumulus are developing in this area too.... :shock:
 
From the NWS Quad Cities:

AT 1241 PM CDT...TRAINED SPOTTERS REPORTED A TORNADO. THIS TORNADO
WAS LOCATED NEAR LA MOILLE...OR ABOUT 8 MILES WEST OF MENDOTA...
MOVING SOUTHEAST AT 30 MPH.
 
WOW!!

According to the SPC, cape has reached 7000 just southwest of the Quad Cities. LI are now down to -14 as well! *edit*:Dewpoints have pooled to near and just above 80 degrees right along the Mississippi River!!! Wow!!

New more agressive cumulus are developing in this area too.... :shock:

Sure are! Just to the west of Davenport in Walcott, the cumulus are definitely firing up! Too bad I do not have a drop of gas.... why does this happen the day before payday? :lol:
 
WOW!!

According to the SPC, cape has reached 7000 just southwest of the Quad Cities. LI are now down to -14 as well! *edit*:Dewpoints have pooled to near and just above 80 degrees right along the Mississippi River!!! Wow!!

New more agressive cumulus are developing in this area too.... :shock:

ILX reporting 82F TD!! That is the highest TD I have every seen...
 
ILX sounding (18Z observed) has CAPE 6700, LI -16, WBZ 13K (probably why hail isn't too large) and 0-3km hel of 100 (but most in the lowest 1km!)

DVN LI was -17, CAPE 4600 but sounding was cut short. GRB 2400 / -7.

DTX was rather wimpy but it's not very humid there - I increase dew's to 70*F and got CAPE 3300 LI -9 (still no helicity.)

- Rob
 
severe thunderstorm warning up for northeast nebraska, looks like cells are starting to fire there and become organized. spc mentions mainly linear convection (bow) but can't rule out the possible embedded supercell given the instability the storms are headed into.
 
Looks like they are elevated storms which don't produce tornadoes... Also a supercell is not formed from high instability, but rotation in the atmosphere.

I'm surprised S WI isn't under a box yet, those cells are right on the southern edge of the current one and moving SE!

Still AMAZED at the turn the IL supercell made since initiation and the cirrus shield extending into MI!
 
"Clearly the situation in Illinois today. "

Agreed - clearly _not_ in Nebraska.

"Some very healthy supercells."

More proof in the pudding that radar imagery is not the end-all in the tornado warning process!

"High CAPE situations always get me excited, ever since I was a kid near Plainfield, 1990"

Yep - I remember being ready to take PSST (Purdue Severe Storms Team) on a nice chase that day and seeing nothing develop other than that storm!

- Rob
 
Tornado Reports for Illinois:
0328 PM Roanoke in Woodford County
Tornado with debris on the west end of Roanoke

0252 PM 8 N Norrmal in Mc Lean County
Brief Tornado Touchdown at 1-30 and Lake Bloomington Road.

0243 PM 4W Roanoke in Woodford County
Large equipment plant destoryed.

0242 PM 1 S Eureka in Woodford
Tornado on the ground moving SE

1243 PM 3 W LA Moille in Bureau County
Birief Touchdown

Wisconsin Tornado Reports:
0346 PM Clarks Mills in Manitowoc County
0347 PM E Valders in Manitowoc County

Mike
http://mgweather.com
 
Things developing nicely in WI for a derecho event later this evening across northeast IL/IN/MI/OH.

Latest ZFP for the Detroit Metro area -
...THEN NUMEROUS THUNDERSTORMS WITH DAMAGING WINDS AND
LARGE HAIL DURING THE EVENING...
 
Air coming into the IL supercell has temps in the low-90's with dew points 76-80*! Ouch...

Can't wait for SPC to change their mode - the MI watch covers about the northern 3/4 of the LP when plotted, but the actual county list includes the entire LP! This isn't like debating counties on the line, the watch actually extended about 40 miles south of where the SPC line ends up!
 
Air coming into the IL supercell has temps in the low-90's with dew points 76-80*! Ouch...

Can't wait for SPC to change their mode - the MI watch covers about the northern 3/4 of the LP when plotted, but the actual county list includes the entire LP! This isn't like debating counties on the line, the watch actually extended about 40 miles south of where the SPC line ends up!

I noticed that as well. The actual watch line extends as far south as Detroit, yet the county list includeds includes counties not even touched by the watch line.

Also, what do you think about this activity in WI? It looks like it doesn't extend far enough SW to get into far southern lower MI... And WFO LOTs latest AFD doesn't look too promising... They say the threat is decreasing due to subsidence behind the supercells (which is visible on the VIS satellite image)... This may stop storms from backbuilding across northeastern IL.
 
If I lived in Benton Harbor I might be concerned, but anyone near a GRR - JXN - TTF line and north should be able to get some. Once the line gels it'll probably take more of a right turn along the theta gradient.

- Rob
 
Sounds like a tornado is on the ground in Manitowoc County in Wisconsin. Can anyone confirm this? Heard the storm is moving very slowly. Possible funnel cloud on Lake Winnebago in Wisconsin. Pretty active day around this part of the state.
 
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