3/11/06 FCST: Great Lakes to Western Gulf Coast

I've been watching this setup for the past few days, and the models continue to indicate strong warm air advection via a low moving through MN. Temperatures forecast to breach 70 with dewpoints approaching 65 acorss central IL into IN. SPC mentioned the cap being an issue, especially on the GFS. However, the nam indicates a relatively little cinh over the main instability axis. Cape is actually forecast to exceed 2000 JKg in eastern IL by 21z with speed shear over 50 knots. Directional shear looks adequate with a nice veering from the surface to 850mb, and 1km SRH values over 150 on the IN border. Saturday could turn out to be a nice chase setup, and a good first run for us midwest chasers.
 
I'm really liking Saturday around the Champaign/Urbana area... going to wait on later model runs in order to fine tune that decision. If Saturday looks good, anyone in the midwest want to chase together? I'm near Milwaukee, WI. Let me know.
 
Well I have to say I'm a little perplexed. The NAM and GFS give SE WI about -4 to -6 best LI values with a considerable band of moisture convergence passing through peak heating but don't generate ANY convection! They do however generate some convection south of us in NE IL. Now I am considering a chase at the moment but the sprawling Chicago Metro area has me concerned. NAM goes highs 65-70 in far SE WI with dewpoints approaching 60 F...its just so frustrating that they don't have any precipitation.

That being said a few models do show some precip showing up in SE WI. Best shot for us looks to actually be Friday Night with best LI's on the order of -2 to -4 and some warm advection precip spreading across. Liking the possibility of elevated hailers here.

If I could see a reasonable chase target outside of Chicago metro I might consider heading out.

Thoughts on N IL/S WI?
 
The 0000z NAM concerns me. It predicts 500-1000 J/kg MLCAPE all the way up to my area :shock:, with localized areas of 3000+ J/kg MLCAPE:
http://www.rap.ucar.edu/weather/model/eta4...hr_sfc_cape.gif

Even though it does not depict much, if any, CINH, it does not depict any development...
http://www.rap.ucar.edu/weather/model/eta4...hr_sfc_prcp.gif

The LI's are depicted to be -4 to -6 over a very expansive area:
http://www.rap.ucar.edu/weather/model/eta4...hr_sfc_pwat.gif

There should be good backing of the winds at 700mb and 850mb across IL/IN:
http://www.rap.ucar.edu/weather/model/eta4...8hr_700_wnd.gif
http://www.rap.ucar.edu/weather/model/eta4...8hr_850_wnd.gif

There will be a strong system at the 500mb level (up to about 110kt):
http://www.rap.ucar.edu/weather/model/eta4...8hr_500_wnd.gif

A very intense jet stream disturbance of up to 150kt will be entering the area:
http://www.rap.ucar.edu/weather/model/eta4...8hr_250_wnd.gif

This may seem like a bit of wishcasting, but I really think that Saturday could get quite rough across many of the areas hit hard today (3/9), only a bit farther north. I think any tornado threat should be maximized over a good portion of Illinois and Indiana due to the good backing of the 850mb and 700mb winds. Now, we wait and see...[/url]

BTW Alex, if I were planning a chase based on this model run, I would go to north central or east central Illinois or western Indiana. Just stay away from Chicago and stay out of the Illinois River Valley (try to cross on really major routes ala I-39). Then again, I wouldn't plan anything for final until tomorrow night.
 
Well, I spent some time on the 0z run. There look like two areas of potential initation. One is the cold front draping southwest through MO, off the surface low in Iowa/MN. That cold front is going to push through into IL later in the evening. If that is the only show in town, I think our chase chances are shot. With the extreme amount of shear, a nasty squall is inevitable and it will be booking.

The second area, and the one that I'm rooting for is the sector behind the warm front extending east southeast across central IL. There is a big hole in the CINH over the instability axis at 18z over central IL, and thus I think this would be a good starting point. However, vertical velocities are silent in the vicinity, only popping up on the cold front later that evening. The 2000+ cape bullseye is still stuck on Champaign at 21z. With the speed shear around 60 knots, we'll need a source of lift (the warm front?) and we are set.

Right now I'm eyeballing an area from Peoria to Lincoln around noon, and I'll move east with the instability until the storms fire, which should be in the early afternoon. I think its important to stay on the nose of that jet. If the warm sector doesn't pan out though I think the day is going to bust with a nighttime squall. I hope SPC is right about scattered to isolated storms developing across IL in the afternoon.
 
WI is out of play at this point, unless something drastic happens in the next 24 hrs. That's ok by me, since chasing around here with trees and traffic is nerve-racking at best.

IMHO, the I-39 cooridor from the Rockford metro area south will be in play and I think Skip is on track with Central IL. If past history means anything, I think you guys could camp out in the Lincoln NWS parking lot and let the storms come to you then move east with them. It appears that region of IL is it's own little convective hotspot.

I'll be in DuPage county all day, but if something pops to the SW of there I might head down and play it. Any storms that form will be hauling butt so without an ISP escort, I'm guessing we will have to pick and choose carefully. I'd think that Tony will either get some discrete cells forming around 1400 local time, or he'll get stuck with the convective trash that formed into a squall line around sundown.
 
I think that, after almost going out and chasing the last system across OK but deciding against it at the last minute......I'd lean more towards sticking someplace with the best shot at some decent, deep moisture.

ATTM, this looks like AR, with the GFS advertising 65+ Tds by 0Z Sun. With that, it is not unreasonable to expect CAPE values exceeding 2000 somewhere. Paint that over a 50+kt deep layer shear value somewhere, and you've already got my ears pricked up. SPC also seem to agree, with another early-March-looking, horrendous 30% hatched area for severe probability blanketing the Arklatex and the whole of AR.

Maybe a lucky chase over the Bootheel/northeastern AR will be in order? Starting point Jonesboro, AR? Not bad chase country I understand.

That's my pigeon-hole-cast. Maybe more later. Good luck to anybody who gets the machettes out and chases.

K.

>>[insert witticism about the forecast date being my birthday here/]<<

:wink:
 
Resonding to Karen:

NE Arkansas is not a bad place to chase. A historical tornado maxima lies NE of Little Rock to the bootheel of Missouri and east of Batesville-Greers Ferry Lake. Roads are flat, outside of Crowley's Ridge, and extremely flat when east of the ridge in the Delta Valley farmlands. For spotting, a mixture of trees and fields covering up to a few hundred acres where you can find a good peek at storms. Avoid anything south of I-40. Jonesboro has a wi-fi hotspot at the Super 8 in town.
 
Yes, the thread title should be reflected to change the new target areas running from AR to TX.

As for IL, the 12z run still looks quite promising with 3000 JKg plotted west of Springfield at 21z and a 100 knot midlevel jet edging in. Right now I'm eyeballing an area from Springfield to St. Louis, right along the best instability and where the jet will catch up with it that afternoon. CINH looks weak so I'll be out there early.
 
I was skeptical at first but now that the GFS breaks out convection along the dryline in East Texas I do believe this is going to be a chase opportunity. Simon and I may just end up packing up our Stormgasm booth early at the TESSA convention. But the cap is going to be strong, but hopefully the dryline and large scale ascent associated with a curved upper jet streak will be enough to break it. We shall see.
 
Perhaps im being to biased to not wanting to drive 600 miles to IL or MO, but as of right now im planning a chase to eastern Iowa. GFS/NAM show the low in MN as rather weak but GEM Ensemble/RUC/UKMET show potiental for a much stronger low pressure system (SD/MN). Both NAM & NMM-WRF show show a 999mb low in C IA around 21z with another low in MN. Both also show convection breaking out around 21z about 60 miles E of Des Moines. NAM shows 300 j/kg 0-3km CAPE, which im highly skeptical of.

Also, 30-35kts 0-3km shear vector (not much shear above 3km) but not a very favorable orientation of deep shear vector (near parallel to cold front. The idea is the storm moving NE would move to the WF (near TP) and then ride along the boundary providing plenty of 0-1km SRH for tornadic possibility. Honestly, a long shot and central/south IL looks much better. If I actually followed through with this, storm motion which starts releatively reasonable 25-30kts gets a little fast 40kts. Im real skeptical of 60 degree dewpoints pushing into E IA tommorow. If distance wasn't a factor I would be in S IL or SE MO.

-Scott Olson
 
Definitely a window of favorable parameters in eastern Iowa, not so much for tornadoes, but severe in general. I was surprised to see my BUFKIT lit up with numbers!

Problem is that window ends right around early afternoon. Something to watch, but its kinda a long shot.
 
Based on the 12Z Eta, there are two places that I believe hold real promise for tornadic supercells tomorrow. First, the warm front could be a significant player if instability can develop along and slightly north of the front. Places that will be primed in this first area include the MN/IA/WI border region southeast to C/N IL to S/C IN. Tremendous shear will exist (as usual) on the north side of this boundary. Should storms form and be relatively discrete, I would expect at least a few tornadoes.

The second area to be considered will be N AR into S MO. High octane moisture is in place along the Gulf Coast and should advect nicely into this region by 00z tomorrow (according to the Eta). As a result of this and cooling aloft, significant CAPE should develop tomorrow. Though shear is certainly lesser than areas northward, sufficient shear should be in place for supercells. What intrigues me now is the spotty lack of CIN (according to the Eta) along the border region of AR/MO. This suggests to me that several supercells should be able to form in this region. With the high degree of CAPE and the increasing magnitude of the ll shear toward dark, a few strong tornadoes appear possible.

Gabe
 

Simon and I may just end up packing up our Stormgasm booth early at the TESSA convention.

Anyone else planning on going to TESSA, and now having thoughts about chasing instead? I am torn right now.

TonyC
 
For those thinking of SE MO, NE AR, and S IL, study up on your topo maps, bridge crossing and forest areas. In Missouri, don't even think of crossing west of Highway 67 no matter what the models have (and that is still too hilly). Don't forget where you are in SE MO as well, since there are only a few bridges across the Miss into S IL. Southern Illinois is a boatload of forests, and Arkansas has its good spots as I mentioned earlier. Good luck for those chasing tomorrow, I think just east of STL metro and to the south and east will be prime tomorrow during the late afternoon and early evening.
 
Tomorrow would probably be my first chase, but I have company coming over, so I'll be relegated to storm spotting tomorrow. I'll be sure to post any reports.

BTW, if the 18z GFS and NAM are to be any indication, tomorrow could get really wild up this way...
 
It will be interesting to see if anything "pops up" in southern Wisconsin tomorrow afternoon. This area is usually a bit too far north this time of year, but time will tell :)

Pat
 
I'm actually liking the chances for tomorrow. Right now I'm aiming on N/C Illinois area. I hope that we don't get too much precip overnight in that area or S WI. If the Cape can get into the 500-1000 region that should be enough to get it started by 3 pm. Dp are forcast in low 60's and the warm front will be in the area. An impressive Dry Slot is now over central IA moving slowly east. I'm hoping that gets here by 4 am CDT and clears us out for what i think will be a good start to the '06 season.

Gotta think positive!
:D
 
This is actually a bit reminiscent of Utica (I used the local meteorologists' "U" word), only pushed forward a couple hours in time during the day.
 
Ok, I will state my thoughts on tomorrow for Southern Wisconsin....

1) The warm front will end up positioned from approx Sheboygan west to Fond du Lac west to La Crosse.

2) The lake boundary will end up positioned from Fond du Lac south to Waukesha south to Twin Lakes

3) Skies will clear shortly after 9 am allowing heating during peak hours of the day

4) Temperatures will rise way above guidance and top out between 65-68 degrees and dewpoints will rise to the upper 50s. Some locations may near 70 degrees.

5) After about 6 hours of heating, with slightly backed winds, a moist, slightly capped atmosphere with plenty of moisure, scattered t-storms will begin to develop over SW WI and begin tracking east northeast. They will take on supercellular characteristics.

6) They will then near the lake breeze boundary and that will be their window of tornadic development because once they cross the boundary the stabilizing atmosphere will eat them up.

7) I think a strong tornado is not out of the question tomorrow in S WI.
 
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I'm not too impressed with Tx chase potential tomorrow. Looks to me like it won't get reasonably good until 0z and that will be mostly in far east Tx in pine woods. The best place is the intersection area of Tx/Ok/Ar and by 0z it looks somewhat favorable for supercells and tornadoes. Problem is it will be dark soon thereafter and you will be in hills and very tall trees I believe. NAM also shows precip breaking out early through day, but I don't really see where it is coming from unless from daytime heating as 500mb is showing subsident DNVA and wrong side of 300mb jet. Cinh seems to be fairly strong until 0z map - but hard to say how many hours before that it breaks loose. Actually between 21z and 0z may be a good time near that location but like I say terrain is very difficult here. I doubt it will be worth the effort.

On the other hand if it can develop a little differently and further back west in Tx than currently shown then maybe it will be worth messing with.

Right now I doubt I'll be making the effort unless something changes. Have to paint the house anyway.
 
Ok, this is now looking real good. Saturday 3/11/06 is the first round of madness. I am still heading down towards the La Salle, IL area. If possible i will stay overnight for the next day which I am about to start a new thread on. I have a feeeling in my gut that a few of you chasers might have already felt; the feeling like this is for real! No forcasting here anymore, I'm going out and getting me some action.
 
Clouds overhead ATTM here in Dallas and visible sat shows them covering most of NE Texas.

Glancing ahead, looks like Texarkana looks to be a safe bet for a target today. Moisture is well on its way with TDs already in the mid 60s across the target area with weak SE winds. Vis sat showing a couple outflow boundries; a stronger one in North Central Arkansas and a weaker one in Southern Arkansas. Wind shift is evident on the northern one.

The ETA is forecasting CAPE over 3000J/kg over NE Texas, SE Oklahoma, and Southern Arkansas. Helicity values are there as well, not as high as they could be, but in the neighborhood. Jet max is still off to the west and think that'll aid in what oughta be a monster day tomorrow.

There does appear to be an 850mb max shooting straight up into Arkansas and extreme eastern portions of NE Texas and SE Oklahoma. High values of moisture will be found over the area all day, so for a change, that won't be a problem!

My reservations fall in chasable terrain; as I've already enjoyed a day in Arkansas this week, I can vouch for its lack of chasable terrain. Not sure how the southern portion of the state is, nor NE Texas, but I'm too close to say no. I'll probably show my face at TESSA and head out and up I-30 to Texarkana for lunch, data, and either and see and wait.

Between now and then, we need to burn off these clouds and erode this thick cap. Oughta make for an interesting day! We'll see!
 
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