10-29-04 FCST: Midwest & Plains

Not sure what that adds to the discussion - but the HWO from Green Bay does mention severe...
Click to expand...

Chicago is mentioning severe now as well. They did not mention severe last Friday, and that verified. I've looked at skewT plots of various stations around the region for various hours of Friday. The ETA model is showing the best forecasts of CAPE/SWEAT/LI, etc. And those hodos are twisting and looping.

KLOT 33 hr ETA

CAPE > 2500
SWEAT > 350
LI < -5
Supercell potential > 70

Looking good?
 
Looking at the 12Z ETA, it looks like the best chances extend across southern MN into WI along the warm front/cold front intersection... I'm thinking the ETA maybe a bit overdone with mositure and instability across this region as well, having Td's new 70F... I would go closer to 65F.

Moderate low level forcing is evident via 850-700mb Vertical Velocites (I don't have access to SFC convergence fields). SFC winds are southerly, primarily across WI, veering to the WSW at the mid levels, allowing for helicities 200-300m2/s2 and higher near the warm front. A 500mb jet max of 70knts is also nosing into the region, which may also enhance lifting, and increase 0-6km shear further more...

What is concerning me is the ETA doesn't output any QPF into the unstable air, which may indicate that forcing isn't strong enough to even get things going...

It look's like initiation would occur in northeastern IA/southern MN, and advect into western WI... I still think the ETA maybe just a touch too fast, but 21Z looks good for things right now...
 
Well one thing we got going for us compared to last week's storm is there is FAR less southern Pacific grunge cloudiness in the way. It looks like the boundary layer is going to get full destabilization, which is a big plus to me. Also, already Td's are over 70 degrees as far north as central MO and southeast NE. I'm fairly confident we'll see some decent storms tomorrow across the southern third of MN and northern IA, translating into Wisconsin later in the day. Just how far south they build is the question.

As far as tornadoes. Well with small dewpoint depressions and decent shear, I am expecting tornadoes tomorrow, particularly in southeast MN....
 
After spending the last couple hours with the models, I think from a parameters perspective this is a pretty interesting setup. Still, as it was pointed out, the ETA is pushing instability to hard. Keeping in mind that ETA didn't verify to well overall for yesterdays temparture with a tendency to overheat. Intial chase target will be La Crosse Wisconsin / on border with SE Minnesota. Should be just partly cloudy allowing decent heating. Models show QPF in this area after 18z (GFS, WRF). 2000 JKG pegged in this area of clearing skies, therodynamics are good and get better. So im still waiting here in Eastern South Dakota trying to decide if I should take tommorow off.
 
http://www.geocities.com/ilxwx/oct29outlook.jpg

Made my own little graphical thing since I suck at explaining things. Thats my take on tomorrow so far this evening. The black...would be the equivalent of a slight risk...for just a general severe threat. The red area highlights my favorable area for supercells and tornadoes, with a hatched basically just being the highest threat area for tornadoes.

Things should get going decently early in the afternoon, right on the western edge of my hatched area. A good cluster of supercells is pretty likely, producing a few tornadoes. Further south, outside the hatched area, shear and cape are still pretty good down into Illinois, but a trigger is more of a question. Isolated storms are still possible though, and with the expected shear...moisture, anything that does go should be supercellular.

Then, later in the evening and overnite I think a squall line should develop along the front...this would threaten the areas outlined in black.

Just my take now, as things are becoming more clear now that its only a day away. I still wont be able to leave until 2 or 3 pm...so i cant go much outside central Illinois...If i could, I would target somewhere along the Minnesota/Wisconsin border...also near LaCrosse, as I heard someone mention earlier. But...as stated, ill just play the area further south, and hope I get lucky.
 
http://www.geocities.com/ilxwx/oct29outlook.jpg

Made my own little graphical thing since I suck at explaining things. Thats my take on tomorrow so far this evening. The black...would be the equivalent of a slight risk...for just a general severe threat. The red area highlights my favorable area for supercells and tornadoes, with a hatched basically just being the highest threat area for tornadoes.

Things should get going decently early in the afternoon, right on the western edge of my hatched area. A good cluster of supercells is pretty likely, producing a few tornadoes. Further south, outside the hatched area, shear and cape are still pretty good down into Illinois, but a trigger is more of a question. Isolated storms are still possible though, and with the expected shear...moisture, anything that does go should be supercellular.

Then, later in the evening and overnite I think a squall line should develop along the front...this would threaten the areas outlined in black.

Just my take now, as things are becoming more clear now that its only a day away. I still wont be able to leave until 2 or 3 pm...so i cant go much outside central Illinois...If i could, I would target somewhere along the Minnesota/Wisconsin border...also near LaCrosse, as I heard someone mention earlier. But...as stated, ill just play the area further south, and hope I get lucky.
Click to expand...

That area might even need to be jogged to the west a little... The 18Z ETA and GFS really put the breaks on, and slowed the system by 3hrs. The system also appears much deeper on the 18Z, will have to wait and see what the 00Z data shows, but I am thinking it may be just a tad slower than the 18Z...
 
By my totally ignorant, seat-of-the-pants reckoning, the way the upper level low is tracking looks to me to produce a nice 3-point around where iowa, missouri, kansas, and nebraska all come together. Out of my range so I'll just sit here in SE Wisconsin & hope to get lucky.
 
ETA continued with the slowing trend with the 500mb center of vorticity... The event is still a good 24 hours away, and I still think it could slow down even further, possibly another 3 hours. 00Z RUC2 FH12 is stronger than the 00Z FH12 ETA, and a stronger solution would cause the system to slow. Other than that, the ETA is really crankin the low and mid level winds up with this system - 50knts at 850mb and 80knts at 500mb...

These winds increase as the system deepens, with a 500mb jet max of close to 100knts and 700mb winds of 70knts by 18Z TUE (and this is actually dropping into the mixing layer in the CAA!)...

VERY VERY interesting, this could be a bigger potential than what is currently being let on for the eastern half of the Midwest and Great Lakes (which will be a new thread tomorrow)...
 
Warm front passed through my area a little bit ago. Dewpoint's on the rise; currently at 63. Clouds are clearing up as well, so hopefully there won't be any tomorrow before the storms can fire up.
 
Foggy beyond belief here right now. APT obs has visibility under 1/16th of a mile right now...temp and dp even at 64. Not sure about cloud cover...little foggy to tell. Also narrowing down a target...likely go around Macomb or Quincy...would like to be further, but I still wont be able to leave my home until 2 or 3 pm...But I like what i see in western Illinois...around the IA/MO/IL intersection.
 
This system is moving slower than the previous forecast... I would target central and western IA and middle/southern MN (mini-supercells along the warm front)... Anywhere further east than that, and it will be getting dark by the time the storms arrive, and they will likely be linear by then. Instability looks good, as well as SRH of 200-300m2/s2, so a few tornadoes are certainly possible in the mentioned area...

For points further east... If the ETA has it's way, expect a line to roar through between 00Z and 06Z SAT... (Eastern IA around 00Z, and later points east)...

Also of GREAT concern is the ETAs' lack of QPF for the entire event across that area - That's how the last event portrayed things, and everyone discarded it... It still possible that forcing will be a little too difuse for the amount of shear...
 
I can't believe I'm actually going to say the following words in the exact sequence that I'm going to say them in: I hope that the severe weather for tonight is a bust, at least in SE Kansas. LOL.

The NWS in SGF is calling for some tornadic supercells to develop after 4 PM. If anything, I just hope they move out of Kansas by 10. Never in my chase career have I wished that severe weather wouldn't happen, but tonight we've had plans for two weeks now for tonight (it's outdoors) and now htey're calling for rain and storms.

LOL. Oh well, hope some of you get a chase or two in today.
 
AN UPGRADE TO MODERATE RISK MAY BE NEEDED IN LATER
OUTLOOKS.

The new Day 1 is out. The tornado threat 5% has been greatly expanded. Wisconsin and Illinois are now in a hatched area for significant damaging winds. I think today will be a far cry from last Friday. Skies over this risk area are going to be partly sunny. Plenty of insolation for a juiced up atmosphere! I would say probably no bust.
 
You must log in or register to reply here.

Similar threads

adlyons
2016-10-04 EVENT: TX, OK, KS.
2
Replies
24
Views
10K
Jeff Duda
Jeff Duda
Quincy Vagell
2017-02-28 EVENT AR/IL/IN/MO
Replies
2
Views
3K
Jeff Wright
10/18/04 FCST: Midwest
2
Replies
15
Views
3K
Bill Schintler
Robert Dewey
06/29/2005 FCST: MIDWEST
Replies
8
Views
3K
Mike Hollingshead
Ben Prusia
3/29/05 FCST : Plains
2
Replies
17
Views
6K
Philip Flory
Back
Top