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

[Mikey Gribble]

Those storm motions heading into western Missouri are going to be a killer. It is going to be like the Sedalia chase. You better be out ahead of it and stay ahead of it until it gets ready to tornado because odds are you aren't going to be able to hang with it for more than an hour given road networks and storm motions. I hate the lack of directional shear, but when you look at SR winds it is a different story. I really like the idea of getting on a tail end storm in SE Kansas. The NAM keeps pointing towards that possibility with good consistency. As of now I would target Nevada Missouri. That ought to put you far enough down stream from storms firing to adjust North and South before moving back West to intercept. Tornadoes do seem like a good possibility, potentially a couple strong ones and even long track given storm motions, but I don't think this is a high risk setup.

 

[Andy Rice]

Still a lot to work out... but it looks to be an interesting day. As an aside... I believe that this is the first day 3 45% that WI has ever had from the SPC.

 

[Donald Giuliano]

Have been keeping an eye on Thursday in the hopes the system would continue to slow down, and finally took a break from examining Wednesday to look into Thursday more closely. Wow, am I impressed, I like Thursday a lot. Plentiful CAPE with no cap, a strong dryline initiating storms, intense LL shear, and great hodographs. I may have to take the day off for this one.

 

[Andrew Pritchard]

I think Thursday will be a high risk merely because of how widespread it will be (EDIT: just realized how redundant that statement was). Wednesday holds better sig tor potential in my opinion, but I think the overall severe reports could blanket a chunk of Iowa, Missouri and Illinois.

Each run the low levels get more southerly, but I still think we may end up with a linear mode. If I had to pick a preferred location it would be eastern Iowa right now. Eastern Kansas and western Missouri may stand a shot, but with storm motions as they are progged, I'd rather sit at home than chase those speeds in that terrain.

Storms will likely explode in central Iowa a little east of the I-35 corridor, so with rapid storm motions I'd likely target a bit east of there even around Iowa City potentially. Supercells are possible initially with an associated tornado threat, but I have to believe we'll eventually end up with a linear complex with significant wind damage likely, which will likely end up being the reason for a potential high risk issuance. Don't think any high risks will be issued because of tornado potential.

 

[Ilya Neyman]

Time for me to comment some. I've been skeptical of the Wed. setup since about Sunday (when I heard about all the commotion and looked at the models myself). Really no need to retype all that has been already expressed which includes moisture/temperature concerns, system timing, direction of shear, initiation, when and where etc. etc. Looks to be an event, potentially sizeable with extent of the convection that does fire. Should see some large hail, damaging winds and probably some tornadoes, one or two strong are possible, before activity goes linear/MCS during the night.

I too have been becoming more interested about the prospects for Thursday, and this setup could produce some significant severe.

Both the NAM and GFS are in astounding agreement that moisture will not be a problem for this day bringing a large tongue of 70 dewpoints up across the southern Plains and into the Midwest. This, I believe is very reasonable as strong southerly winds will be advecting northward directly out of the Gulf of Mexico AFTER the LLJ sets up and intensifies Wed. afternoon/night. Also models are progging mid 60s dewpoints to be firmly entrenched across the southern Plains as early as 12z Thursday.

Solid moisture, very warm temperatures, and okay temp dewpoint spreads due to the moisture will be the fuel in place underneath very good shear. The cap will be an issue, but looks to be much more breakable over a larger distance when compared to Wed.

The area from the Midwest down to the eastcentral Plains could get pretty active come Thursday afternoon, however, further south along the cold front needs to be watched very carefully. There is a chance that convection can fire, at least locally and in a more isolated fashion down into OK, and perhaps maybe as far south as the Red River/N. TX. It's in this area where the strong moisture/instability and wind shear overlap will be quite impressive IMO that should storms manage to get going they will have the potential to be significant, possibly in the form of intense supercells, potentially tornadic, late Thursday afternoon and evening.

I agree with the previous posters that out of the two days Thursday looks to be the best candidate for a high risk, should one be needed.

 

[Jim Hunt]

I know everyone is out today on the big chase but I will agree with my limited forecasting that Thursday will be a very good day. Since I have to work, I think I will remain in Indiana but will see some potential for excellent lightning in the overnight and maybe a few rumblers eary before the sun falls.

 

[Scott Weberpal]

Given the odds of some mode of significant severe occuring tomorrow, I'll likely wander into Iowa. I had using pattern/event recognition, but this like it could wind up being eerily like 5/30/04 with strong squall line developing early, and strong tornadic supercells developing ahead of the line and remaining isolated long enough to produce a few decent/strong tornadoes.

Though deep layer wind fields will be largely unidirectional, 36 hour forecast soundings in E. IA show excellent storm relative winds, and forecast 0-3 KM CAPE inv of 250 j/kg...forget the 57 kt forecast storm motion Go go gadget jet pack!

I do expect a few strong tornadoes tomorrow, the atmosphere has had a tendency for doing so this year.

 

[Mikey Gribble]

I really don't see a serious tornado threat emerging tomorrow. The CAPE and deep layer shear combinations definitely call for a serious severe threat, but not a major tornado threat IMO. I never get really optimistic for toradoes when low level winds are veering badly, especially when the initiating boundary runs NE-SW. I think North of KC along the boundary, a combination of too much forcing and storm motions not being normal enough to the boundary are going to favor more of a linear mode of convection fairly early on. SPC mentioned 1km shear of >20kts as being one of the indicators of strong tornadoes. I am a huge fan of 1km shear, but I don't think that is enough in this case for wide spread tornadoes. Anyways, my fundamental problem with this setup is directional shear and storm mode. I just don't see this being a major tornado event with that poor of turning. I think the majority of tornadoes in the moderate risk area will probably be burried amongst a cluster of storms and picking the right storm could be tricky.
Don't get me wrong, I think there will be several tornadoes NE of Kansas City, but I think there will be a small number of toradoes up there relative to the number of storms. Anytime you have that kind of deep layer shear and CAPE combinations a stong tornado or two are also possible, so I don't rule that out either. I just really don't see this being a high risk or even high end moderate based on the tornado threat and from a tornado chasers perspective I would rather target the area South of KC.
South of Kansas City I think the tornado potential improves slightly. Warmer mid level temps and less forcing will hopefully keep storms more discrete. The NAM has been consistently hinting at a tail end storm in SE Kansas and I think that is going to be my play tomorrow. I do anticipate a couple tornadoes in eastern Kansas, but I don't think strong tornadoes are a good possibility.

 

[Travis Carlson]

A VERY DANGEROUS significant severe wx event is on tap for tomorrow. Deep layer shear is OUTRAGEOUS for this time of year. The storm system deepens to around 980mb. Moisture is good 60+ dew pts. Instability is great with 2000J/kg anticipated. However, two things I don't like. Storm initiation will be around eastern, IA it seems. The storms will be moving VERY VERY fast. Probably on the order of 50mph. With that speed keeping up with the storms will be a problem and you have to worry about the storms crossing the miss. river at a point where u have no road network to cross the river. So initiation and storm speeds are my two biggest concerns. I think supercells will definately be possible on the onslaught in eastern, IA but transition quickly to a derecho with damaging straight-line winds trend being the biggest threat. Wind speeds over 60mph would definately be possible. I'm not passing up a MDT risk even if it's extremely dangerous. The drive home should be a fun one though. I like Waterloo, IA or Iowa City, IA somewhere there or to the south. I do think convection from tonight should not be a problem and the MDT risk area will be convection-free by tomorrow morning. I'll possibly update later, but if not good luck everyone who ventures out for this one and stay SAFE!!!

 

[Jordan Hartley]

I too im thinking about heading off tommorow pending I can get off work. If I do I will probley be chasing the tail end charlie pending the line doesnt fire all at once all the way down into OK and if it does I just hope its a broken line. It would be nice if we could get another Nickerson type setup in SE Ks tommorow without the storm chaser convergence . I have a feeling things might change for the better tornado wise since the models havent had a good grip on this storm until 6-12 hours before the event. ****Wishcasting**** Hopefully we can keep this sfc low in E CO together and get it to march more E than SE so that the winds in KS will back out of the SE like its starting to do now in W Ks.****Wishcasting**** Have fun anyone who heads out tommorow and be safe.

 

[Jim Zandonai]

I agree with a tremendous set up for this area over EC IA and NW IL.
Probably the best so far this year. Yes for chasing it could be very tough if storms are moving that fast and you get behind one. I will be ahead of any supercells if they are discreet here and if heading in a east or NE direction look to interecept from here in RFD area but only if I see a discreet supercell or perhaps a bow that would miss RFD will I go after it and its relatively close.
The way its sounds if a Derecho develops especially later you wont have to go far. More then likely I'll remain in the local area as we are expected to be under the gun too. Good luck to all !

 

[Brandon Sullivan]

I think I will be working ham radios at the Local NWS office.. So I wont be chasing, but Ill certainly be in the mix. Good luck all... May see a high risk tommorow.. Maybe even see some PDS severe watches.. Havent seen one of them in a while.. Still looking good without a doubt.. I dont feel bad at all about not going west for tonights stuff!

 

[Joel Wright]

I have to admit I'm not as optimistic as I was last night. Surface winds stayed backed a little longer on last night's runs. Tonight's new runs are considerably more veered. Still waiting on the GFS, but I'm sure it paints a similiar picture so close to the event.

As many above have said, the best chance for longer lasting discrete cells will be down south. The cap will be more of an issue down there, but it should be broken before dark.

Up north things are going to be very linear I'm afraid. However, once these cells organize into a solid line and develop a strong cold pool, there will very likely be some seriously damaging wind episodes. With storms moving at over 50mph, and with all the momentum aloft, this is a no brainer.

 

[Ben Prusia]

It appears that tomorrow will have two seperate areas of severe weather, the first being a possible derecho/linear convection going up in SPC's Day 2 moderate risk area, and the other being an area in east central and southeastern Kansas into northern Oklahoma where more isolated convection is possible.

With appreciable small 700mb temperature increases at least holding off early initation, a target area of SE Kansas is becoming more favorable for supercell development during the day on Thursday. A dryline will make its way to the east through east central and SE Kansas with an all important second day of strong southerly winds that will bring up decent moisture and raise the dewpoints to fuel any convection. An all important factor for tornadic development is that this model run is bringing the surface winds more to the south than previous model runs which will hopefully increase the chance for tornadoes.

Looks like I will be out in SE Kansas somewhere, more details to come tomorrow. It was kinda interesting to see the 0Z NAM Skew-T for Chanute, Kansas at 0Z Friday with a supercell potential of 99.0%. We will see.

 

[Mikey Gribble]

The 00Z NAM makes the tornado potential look even worse for points North of Kansas City than it already did. I just really don't see a significant tornado threat tomorrow. There really isn't anything going for tornadoes in the moderate risk area aside from strong wind fields, which speak more to the severe threat than tornado threat when lacking directional shear. CAPE has decreased and precip. is much weaker on the 00Z run. I don't quite understand that since the cap should be eroded by 00Z. Anyways, as far as tornadoes go I wouldn't be expecting anything unless you are chasing Kansas, and I don't think it's that great down here either. They more than likely will have a few tornadoes up North, but they are going to be few and far between IMO and will probably be with imbedded supercells in lines or clusters. High winds should be the primary threat over the moderate risk area.
Over the entire risk area tomorrow storm motions are not normal to the boundary due to the NE-SW oriented front/dryline, which could cause problems with storm modes. Very strong deep layer shear and moderate instability will be quite favorabel for supercells, but the veering low level winds are going to seriously inhibit the tornado threat. A few tornadoes will be possible just because of the very strong winds at all levels, especially 1km SR winds >20kts, and I wouldn't even rule out a slim chance of a strong tornado or two, but it is unlikely IMO.
In Kansas, storm mode should be better with a higher probability of a couple discrete supercells or at least a tail end storm. Conditions are still marginal at best for tornadoes IMO. CAPE and deep layer shear combinations in KS will be extremely favorable for supercells, but (once again) veering low level winds will put a serious damper on the tornado threat. 0-3km SRH is pretty weak, but 1km SRH is a better indicator of tornadoes and it is a little more respectable, but towards the lower end of the spectrum on what I like to see for a good tornado threat. I haven't done much forecasting yet so I will take a closer look tomorrow morning. As many have already said, storm motions are going to be nasty, so I plan on setting up well ahead of where I think storms will fire. In my experience the best way to play a day like tomorrow is to set up NE of where you expect a tail end storm to fire, jump on storms as they mature, and stair step your way South until you get on a storm with unimpeded inflow. That is what I will be doing. Good luck to everybody out chasing tomorrow. I hope I am wrong on the tornado potential.
BTW I would be shocked if they issued a high risk tomorrow and on the off chance that they did it would be for high winds. At least that is my two cents.