10/18/07 FCST: WI/MI/IA/MO/IL/IN/OH/KY/TN

[Joel Wright]

Wow. Latest models are really speeding this system up now. Damn near six hours faster in fact. Possibly an early show back in Illinois into Indiana and southern Wisconsin. The best area may in fact be in the western half of lower Michigan now...

 

[Scott Weberpal]

From what I see, the 00z WRF has actually slowed things down a bit from the previous run. The warm sector is still amply anchored in E. IL at 00z, where as previous runs had the warm sector pushed into IN by 21z.

I am much more excited about the vertical shear profile at this point, it is much less unidirection from sfc to H7. It wont take a lot of veering with height to get deep convection to rotate tomorrow, especially in the lowest 3 KM. I am, however, worried about strong linear forcing. May be chasing a broken line with embedded supercells when all is said and done.

Regardless, I'm much more optimistic strictly based on the 00z WRF. Nothing will be more useful and visibe, and WV satellite tomorrow. Once the dry slot begins to erode the deck, it won't be long until convective bliss begins.

 

[Brandon Sullivan]

ok Scott.. Thats what I was seeing too.. Still looks to be lots of parameters coming into place.. Just a game of sit and wait now.. Well have to see what happens.. And wait for new SPC day one outlook..

Based on 00z. Im thinking more east than north. I will head into central IL and see where I need to go from there..

 

[Robert Dewey]

Latest 00Z NAM initiates things around 03Z/FRI across E IL into SW MI. Shear still looks very healthy (0-6km 50-80knts, 0-1km SRH +250m2/s2)... and instability lingers well into the evening and night hours with LI of -6C and MLCAPE of 1000J/KG (with no CINH) through 06Z/FRI from MI southward.

I could also foresee some action along and just south of the warm front, where there will be a pretty tight instability gradient and very strong directional shear.

Of interest: http://w1.spc.woc.noaa.gov/exper/archive/events/011024/index.html

 

[Andrew Pritchard]

I agree, it has certainly slowed down as I kind of thought it might in the back of my mind. Such a big system, they always seem to slow down slightly the day before on the models. Preliminary thinking had things hauling into Indiana by mid afternoon, but by the looks of things now Indiana might not see a big threat until dark. I think surface winds are as good as we are going to get right now being prog'd at southerly. Fast storm motions will actually help offset that somewhat in the storm relative flow side of things. Without going too far into things right now if I had to pick a general area I'd probably adjust my earlier target south to anywhere between Bloomington and St. Louis early in the day, and then areas north and east of there through the afternoon. Naming towns now is probably stupid now before seeing everything, but I don't really plan to stay up terribly late tonite. But, after taking a quick look, it does look like things have slowed and maybe adjusted a hair south to south central Illinois (good news for Mr. Farley!).

 

[John Farley]

(good news for Mr. Farley!).

Mr. Farley agrees! It looks like both the WRF and the GFS have slowed down the eastward progress of the front, keeping much of southern and eastern IL in the warm sector, with good instability and shear. Not too much precip showing on the WRF in this area, but if storms get going they should have a good chance of rotation. I'd like to see a little more directional shear, but there is some, and the EHI values predicted by the WRF in southern and eastern IL and nearby parts of IN are pretty decent - 2.7 in Terre Haute, 3.0 in Mt. Vernon, and 3.6 in Evansville. So, if it looks in the morning like this is going to verify, I will likely be heading out. Good luck to all who do!

 

[Fabian Guerra]

I'm glad to see someone on the same page as I am. My target tomorrow is Bloomington, IL just before noon. I'm thinking the best storms will follow a BMI-Joliet-Chicago line from 1-5pm. I would like to see backed surface winds and I am a little concerned about heavy cloud cover early on. That being said, with a little instability I think there should be a good chance for a few fast moving tornadoes or at least some low topped supercells to be found...

Bloomington, IL forecast sounding for 18Z tomorrow: http://beta.wxcaster.com/cgi-bin/parse_skewt_trace.cgi?model=NAM&fcsthr=018&STATIONID=kbmi

Fabian

 

[J West]

I'm glad to see someone on the same page as I am. My target tomorrow is Bloomington, IL just before noon. I'm thinking the best storms will follow a BMI-Joliet-Chicago line from 1-5pm. I would like to see backed surface winds and I am a little concerned about heavy cloud cover early on. That being said, with a little instability I think there should be a good chance for a few fast moving tornadoes or at least some low topped supercells to be found...

Bloomington, IL forecast sounding for 18Z tomorrow: http://beta.wxcaster.com/cgi-bin/parse_skewt_trace.cgi?model=NAM&fcsthr=018&STATIONID=kbmi

Fabian

That is showing MLCAPE at 2000+J/KG...must be nice. There's no way it's making up this far north. GFS and RUC are putting upi ~1500J/KG and the WRF doesn't even get MLCAPE close to southern WI. I think we may get cut out of the moisture too early due to the speed of the system.

I think the IL/IN/MI guys are gonna get the show, as models are putting the best conditions to the immediate SE of WI.

 

[J West]

I'm glad to see someone on the same page as I am. My target tomorrow is Bloomington, IL just before noon. I'm thinking the best storms will follow a BMI-Joliet-Chicago line from 1-5pm. I would like to see backed surface winds and I am a little concerned about heavy cloud cover early on. That being said, with a little instability I think there should be a good chance for a few fast moving tornadoes or at least some low topped supercells to be found...

Bloomington, IL forecast sounding for 18Z tomorrow: http://beta.wxcaster.com/cgi-bin/parse_skewt_trace.cgi?model=NAM&fcsthr=018&STATIONID=kbmi

Fabian

That is showing MLCAPE at 2000+J/KG...must be nice. There's no way it's making up this far north. GFS and RUC are showing 1500J/KG SBCAPE and MLCAPE and the WRF doesn't even get any CAPE close to southern WI. I think we may get cut out of the loop too early due to the speed of the system.

I think the IL/IN/MI guys are gonna get the show, as models are putting the best conditions to the immediate SE of WI. We'll have the shear, but not much else. I also think that we'll be socked with debris left over from this overnight convection.

 

[Andrew Pritchard]

Bloomington, IL forecast sounding for 18Z tomorrow: http://beta.wxcaster.com/cgi-bin/parse_skewt_trace.cgi?model=NAM&fcsthr=018&STATIONID=kbmi

Fabian

That's nice, but not quite as the soundings for 21z and 0z further south at Champaign and Mattoon.

http://beta.wxcaster.com/cgi-bin/parse_skewt_trace.cgi?model=NAM&fcsthr=024&STATIONID=kmto

 

[beaudodson]

Paducah, KY sounding is pretty intense. High Cape and high helicity. Supercell reading has a 92% risk. If storms can fire further south into KY/TN.MS/AL then there could be some strong tornadoes. NAM is bullish on severe. Has not been much discussion on here concerning that region.

 

[Justin Bailey]

wow! the 00z forcast runs really make E Ar, SE MO, S Ill, W Ky, W tn, and N Ms look like the place to be! frocasted CAPE ~2000 j/kg and helicity on the order of 300 m2/s2!!! im just praying these runs arent some random fluke. if any of this verify's then we will have another active day in store tomorrow...well actually today.

 

[Brandon Sullivan]

well wx radio keeping me up thus far... just waiting for the new swody 1 so i can get some z's and know if it is worth gettn up for!!

models all still look good, so just waiting for SPC to confirm our area's..

Well it has came out, and it shows the high probs for tor moved even more eastward now.. I will play off the 8 oclock and go from there.. if it moves any back west i am headn out.

 

[George Tincher]

I too find myself greatly interested in the SRN portion of the outlined area. SRN IL, the WRN portion of KY/TN and far ERN AR look like they will have very favorable parameters in place for severe weather by afternoon. I was actually a bit surprised by just how much CAPE the WRF is showing in this location by 18z. When you start talking CAPE in the 1500-2000 range or more this time of year, that's not too shabby at all. Soundings also look very impressive. And a quick glance at some sfc obs reveal that temps are already around 70 to the mid 70's over much of WRN TN and KY, with dewpoints ranging from about 68-70! This is at 5:51 AM CDT.

With just a slight break in the cloud cover taking place (I think we have a good chance to see at least some clearning), I think the whole outlooked area has the potential to erupt, and not just the moderate area farther N that most people seem to be focused on. Granted, that would largely be the most chaseable area due to terrain and trees. But there's just something drawing my attention to the area between Paducah and Memphis. The balance between good helicity and the best CAPE seems to be in that area and I'm having a hard time ignoring that. I don't know if we have anyone here on the forums who lives in or near Paducah and Memphis, but if I did, that area would not be a bad place to be today IMO (unless you DON'T want to see severe weather). I consider Memphis and surrounding area very flat and chaser friendly compared to where I dwell, so Plains people, please take that into consideration as to why I keep talking about that location.

I notice SPC elected to bring the hatched area farther S in the new Day 1 across WRN TN which I totally agree with. Though the probability is lower over this region (10% compared to 15% farther N), I think the best potential for an isolated big storm or two may be more likely over this area than farther N, where I expect more coverage but perhaps a bit more cluttered group of storms with all sorts of storm modes.

I know I am probably overlooking several things, as I just glanced at a few things in my morning rush (sfc map, helicity, forecast CAPE, and some soundings). But that's my feelings about what I did see as of right now. I'll look everything over carefully tonight when I have more time and see how the day developed (and most likely why I was wrong). LOL.

Good luck to those who venture out today. But above all, stay safe.

 

[David Draun]

YES! KLOT forecast discussion is holding off on initiation until 3pm or so. I sure hope this verifies. This means I can get out of my class and head toward my target of Joliet south to Kankakee in ample time. The later initiation isn't too farfetched of an idea, given the higher convT's on the forecast soundings. The 4.0km NMM/WRF hints at some discrete cells around north central IL earlier, then blows up a huge squall line from about Terra Haute southward later in the period. It will be interesting today for sure.