06/07/07 FCST: TX / OK / KS / MO / IA / IL / WI

[Bill Schintler]

Chase target for Thursday, June 07

Chase target:
Williamsburg, IA (30 miles W of Iowa City, along I-80). Storms will initiate at 4:30 PM CDT and quickly become severe. A few supercells will be likely early in storm evolution however storm mode will transition into a squall line by early evening and race to the E at 60 mph.

Synopsis:
UA analysis indicated impressive fanning-diffluent pattern over NEB and SD within left-exit quadrant of 55kt H5 speed max. Lead S/WV was lifting through the Dakotas and a wide variety of severe WX was associated with this feature and associated low/WF/DL from SD and now into NEB where a squall line is ongoing. A second ULVL disturbance was located upstream over CO, while a third wave was rounding back of main trough over CA, with very cold temperatures aloft noted with this feature. Also noted was rapid H5 height falls over the Four Corners area of 170m since 12Z, attesting to the unseasonable strength of the system. Very strong flow was also noted at the mid-levels with 70kt SWRLY H7 flow racing through KS. A 55kt LLJ was transporting 18C H85 dewpoints into KS while at the SFC dewpoints in ERN IA were in the low- to mid-60s F.

Discussion:
Somewhat of a complicated SFC map will unfold Thursday as a pre-frontal trough/wind shift line in ERN IA should be the focus for convection, while the main CF will remain well to the NW of the area until late evening. Strong capping, with H7 temperatures of nearly 15C, will suppress convection until late afternoon when the mid-levels cool several degrees. Current indications are that storms will fire along the trough by 23Z, and should quickly become severe in an environment of moderate instability with MLCAPEs to 2000J/kg coupled with unseasonably strong unidirectional shear with deep-layer shear increasing to possibly 70kts by early evening as a 90kt H5 streak overspreads the area. Hail potential will be limited by high freezing and WB zero levels. In the event that SFC winds locally back, embedded supercells with tornadoes are possible; however severe straight-line winds should be the main feature of this event. Tomorrow’s setup resembles the June 18, 1998 wind event where severe thunderstorms moved across a large portion of northern and central Illinois although the H5 flow will be stronger tomorrow.

- bill

 

[Donald Giuliano]

Guess I'm in the minority here, but I still think tomorrow looks great for a tornado outbreak, though I'm a little concerned the storms may mostly hold off until after dark (bad for chasing). There's a strong dryline oriented NNE/SSW with initial storm motions progged to be NE to ENE and right-turners to be ENE to E (depending on latitude). The shear is outstanding, with hodographs looking very favorable for large tornadoes from OK all the way up to WI, especially around/after 00Z. After 06Z it looks like the cold front catches up to the dryline, at which point I'd expect the tornado threat to go downhill fast as everything lines out. As far as chasing goes, I'm especially interested in the southern portion of the risk area (KS/OK/southwest MO) due to much more chasable storm motions, as well as proximity to home.

I would strongly consider going high-risk for this setup, though I'm a bit concerned the lack of widespread storm coverage may not warrant it, particularly farther south.

 

[Shane Adams]

WRF showing a linear mode through Mizzou but interesting blob near OUN at 0Z....all of course subject to change but interesting nonetheless. Just ran into Dave Ewoldt and his two chaser buddies from across the pond (still at 'The Depot', the same cool bar I mentioned in the 6-6 reports thread). We're thinking eastern/SE Kansas into northeast OK.....of course subject to change within the next few hours as the new day 1 is released. Luck to all who venture out.

 

[Jeremy Ludin]

Looks like I'll be sitting this one out tomorrow. First of all, tornado probabilities seem to be limited except soon after initiation late afternoon/early evening. It's looking like storms will go linear extremely fast as derecho parameters are pretty high. I just can't catch a break here in the QC.

 

[Brandon Lawson]

LOL! Target: Norman, OK.

Just got back from Nebraska after an unfruitful chase and was told to look at the 4km WRF by a friend. A nasty looking cell explodes right on top of Oklahoma city. At first, I just laughed at it, but then after checking the WRF and the GFS I think it's highly possible something could go up in central oklahoma. Seeing as how I'm still not very good at forecasting, does anyone have any thoughts on whether oklahoma could go off big tomorrow? I always get excited that Oklahoma is finally gonna see some action for 2007 and then it never happens. But maybe it's possible tomorrow.

Central Oklahoma could be under the right entrance region of the middle level jet come tomorrow which might help be a trigger for storm initiation. Both the GFS and WRF show 70-75 dewpoints in central oklahoma and this looks very reasonable since there are 72 dewpoints on top of Dallas, TX right now. Extreme cape around 5000 j/kg and 150-300 m2/s2 Helicity values are not too shabby either. The winds look more than adequate to support this threat, from what I can see, especially if the low tracks a little slower than progged.

Any how. I'd love to be able to hang back here in Norman if the conditions are favorable, but will make the drive into south east kansas if that looks like the better shot.

 

[Dan Cook]

High risk

http://kamala.cod.edu/SPC/latest.acus01.KWNS.html

 

[Marcus Opitz]

good grief!

Can it be any farther>>> ! I was going to fly up to chicago, but now I may have to fly to green bay, WI lol! I am sure storm motions will be very fast and am not sure of the terrain up there. Anybody chase in WI????

 

[Brandon Goforth]

Hmmm...SPC seems to think the tornadic threat will remain north of MO for the most part. I was expecting it to be a little higher further SW all the way into central OK.

 

[Scott Lincoln]

Hmmm...SPC seems to think the tornadic threat will remain north of MO for the most part. I was expecting it to be a little higher further SW all the way into central OK.

Hodographs were actually looking better on the wxcaster page the further northeast you get from Iowa... Rochester, MN, to Eau Claire, WI, looked decent to me. Fast storm motions but a brief period of the class sickle-shaped hodograph with most of the turning in the lowest 1km.

 

[Todd Sprinkmann]

Hello Marcus and others,

As a lifelong resident of Wisconsin, I can assure you we chase up here.

While I doubt you're really going to book a quick flight to Green Bay (far better to plan a leisurely trip to Lambeau and experience what Wisconsin is really about), I can say this: Wisconsin does have decent chase territory. But it's not widespread. I'm looking at my Rand McNally now and I suggest anyone who is interested follow along with me.

Good chasing in Wisconsin is roughly bounded by a badge-shaped area in the south and central part of the state. Specifically, from the area 50 miles east/west of Beloit on the southern boundary and basically straight north through the Madison/Portage/Stevens Point corridor. And really, all the way up to Wausau in the north-central part of Wisconsin. If you go too far west toward Eau Claire and Tomah and La Crosse, (and a ways east of there) you run into the part of the state that the last glaciers didn't scour down to small hills. That area is tough chasing. You're talking valleys and winding roads and just aggravation. Talking SW, West Central and NW Wisconsin there. Eastern Wisconsin (east of Green Bay thru Oshkosh and down to Waukesha) is better than SW Wisconsin, but it isn't as good as the areas I talked about in the central part of the state. Those Eastern parts have some trees and rolling hills.

Finally, you go way up north in Wisconsin and it's just ugly for chasing. It's a lot like Minnesota when you get north and northwest of the Twin Cities. Tons of lakes, tons of winding roads and forests everywhere. Beautiful for vacationing, but bad chasing. If you see scattered, frequent lakes on your atlas, it's not good chasing.

Now I better take a look at that new Day 1. Not very often Wisconsin is in the bullseye.

 

[Angie Norris]

But still 2% for OK and KS. I've got the day off, so I'm chasing. Will get a definite target in mind a little later. Just from what little bit I've looked at, the dryline looks to stall from the NE to the SW through the middle of OK with moisture pooling east of OKC. There is a huge CAPE spike of ~ 5000J/kg near (if not right through) the same area at 0Z. I'm thinking somewhere near Okmulgee or Okemah may be a good starting point. Will define this a bit later.
Good luck, happy hunting and safe travels to all!!!

 

[Jim Zandonai]

High Risk !
Looks like WI is under the High Risk area due to more of a Tornado Risk with discreet supercells and shear..
Here in N. IL I expect whats been said earlier in the forum: An intense line of storms forming along the front or ahead of it breaking the cap thus giving us a severe Wind threat. More then likley unless I can get a head of a discreet supercell to my SW as it races NE I'll more then likely remain near RFD and spot and report to KLOT with the expected line.
Good luck to all who venture out.

 

[Donald Giuliano]

It looks as though the SPC is pessimistic on the tornado threat south of IA due to frontal forcing on the cold front producing a squall line. I'm having a lot of difficulty making sense of this assessment, as the surface cold front is forecast to be up in the northern Plains at 00Z! The boundary depicted by the models to be initiating convection in MO/KS/OK is not a cold front, but a dryline. Perhaps they're expecting the models' placement of the surface cold front at 00Z to be off by 200-300 miles, and for the front to have already caught up to the dryline by 00Z instead of closer to 06Z? That doesn't seem likely given the placement of the 500mb vort max at 00Z, but maybe I'm wrong about that.

 

[Shane Adams]

Ok, we're still in Mitchell, SD havig just left the Kongo Klub establishment. Chad left welps on Colorado Girl's bum but she liked it. Myself, I fell for the barmaid who was a no-nonsense, married beuatiful brunette. Good times. We rule.

We'll be heading down to SE KS in a few hours. Luck to all.

 

[Brandon Lawson]

It looks as though the SPC is pessimistic on the tornado threat south of IA due to frontal forcing on the cold front producing a squall line. I'm having a lot of difficulty making sense of this assessment, as the surface cold front is forecast to be up in the northern Plains at 00Z! The boundary depicted by the models to be initiating convection in MO/KS/OK is not a cold front, but a dryline. Perhaps they're expecting the models' placement of the surface cold front at 00Z to be off by 200-300 miles, and for the front to have already caught up to the dryline by 00Z instead of closer to 06Z? That doesn't seem likely given the placement of the 500mb vort max at 00Z, but maybe I'm wrong about that.

I'm a little perplexed myself. This looks like the best setup for a violent storm or two, in Oklahoma, in quite a while. Am I missing something?