10/01/09 FCST: NE/KS/OK/TX/MO

[cdcollura]

Good day all,

Thursday may be an "outbreak day" if things slow down a bit. Keep in mind that Wednesday (9/30) may be a chase day as well, as long as moisture does indeed return and the cap breaks.

I am currently en-route to use my "May time off" I did not use 4 months ago, and should be in Kansas in a few hours ;-)

 

[Angie Norris]

I am currently eyeing the I-35 corridor in north central OK for Thursday evening in an area of ~1800-2000 J CAPE. The dryline looks to sharpen up a bit there near the 0Z timeframe, as well as giving us a nice bit of shear. Am I expecting tornadoes? No. Do I care? No. I am expecting a nice squall line however, and will be pleased to get some good shelf clouds and hopefully get punched by the line as it comes over.

 

[Brendon Lindsey]

Well, Just throwing it out there, 18z NAM is encouraging... I think that if we do get enough energy to break the cap out in front of the cold front, we would be in business. I think there will be a moderate threat for tornadoes if the models keep predicting higher cape values. I see there is sufficient shear and moisture, also the LCLs are from 250-500m in Eastern/ NE OK. Also The SRH is pretty high, maybe there would be a big tornado? Well hopefully the CAPE the 18z NAM predicted will verify, that would be awesome, also going off the precip graphic, it predicts a bit of isolation in E.OK and SE KS. That would be cool huh? lol well I guess I'm going to wait a few hours for the 0z to come out and see if its still verifying. Now everyone lets just hope the GFS comes into agreement with the NAM. I am going to go ahead and say I'll be chasing the NE quadrant of Oklahoma Thursday, anything East of I-35 and North of I-40. This is preliminary lol and a novice's take on the setup.

 

[Matthew Piechota]

I agree with you brendon, right now I like northeast OK to extreme northwestern AR. SRH increases nicely from 21z to 0z and has near 2000 CAPE in that area. shear is pretty good and with moisture in the mid 60's we should be ok.

DL looks to tighten up nicely by 0z in central/eastern OK. possibly get a discrete supercell at the beginning and with nice LCL's, maybe a tornado or two but I expect a big squall line by/after sunset racing east.

another place to watch in further north near the sfc low for some possible low-topped supercells.

will have see what 0z runs show later.

 

[Adam Penney]

Well I have been out of town the past few days, and have been following everyone's excitement.

However, this evening is the first time I have been able to personally look at things, and based on the 0Z NAM, I am very unimpressed. SBCAPE across all areas except SC and SE OK at 0Z Friday are <500J/KG. 850 winds are veered badly and pushed well to the east across Arkansas and C/S Missouri.

Perhaps I am missing something, but according this run of the NAM, I dont really see the setup.

Looks pretty awful ATTM to me.

 

[Jeff Duda]

Oh wow, yeah. The 00Z NAM came more into alignment with the GFS runs as of late. It now has the whole system moving through the plains and Missouri valley much quicker. Yuck.

ADD: GROSS! Don't even look at the 21Z SREF run (okay, I mentioned it, so you will probably look anyway). No chance of any surmountable instability north of I-70. The frontal position is closely aligned with GFS runs also. *sigh* ...stupid weather.

 

[Derek Weston]

Awful looking now. This one just keeps getting worse; further east and less instability. OK folks can perhaps play in a squall line...hope for some embedded rotation... CAPE nearly gone for us northern folks. Perhaps a little magic near the low... but not optimistic there either.

Oh well.

 

[CZandbergen]

Looks like the NAM is coming into agreement with the GFS/ECMWF solution. Unfortunate, but is what it is. I haven't been able to see a run of the 0Z GFS yet, but I doubt it is going to backup as it seems to be the solution that the other models are centering on. CAPE looks weak, as others have mentioned veering winds and the cold front is pretty much one with the DL. Looks like a wind event over NE OK. FWIW, the LLJ looks like it will really be kicking up around 0Z. Areas to the east of Tulsa may be in for a rough ride. Nothing to chase that I see.

Oh well, such is 2009...

 

[Jim Bishop]

Well, the WRF trend from yesterday is wrong. It is now trending towards what the GFS/European have been showing. That being a more progressive cold front. There appear to be two areas to play for tornado potential. 1)cold core near the surface low. 2)northeastern Missouri into west central Illinois. Since I'm not nearly as familiar with cold core setups as I am the warm sector, I will only provide a detailed analysis for #2.

Area #2 will probably involve a very fast moving squall line with imbedded mesos. However, the north-south orientation of the cold front as it moves rapidly eastward from Kansas through Missouri suggests the potential for more of a broken squall line with imbedded supercells. This would depend upon how much space there exists between the squall line and the cold front.

The 850mb winds are indicated by the GFS to back to the south-southwest around 50 knots throughout the later afternoon to evening. This beneath a 50-70knot 50mb jet from the southwest would provide adequate shear for supercells. Additionally, surface winds should be out of the south or possibly south-southeast. You put that together with a fast storm motion towards the northeast and you get great low level shear for tornadoes and good low level hodograph curvature.

Unfortunately CAPE values will be limited given the relatively warm 500mb temps. But dewpoints in the upper 50s to lower 60s should contribute to CAPE values in the 400-800j/kg range.

In summary, a fast moving squall line is likely to form along the cold front over eastern Kansas into western Missouri around midday. Should the squall line race far enough ahead of the cold front by the afternoon/early evening then low to mid level wind shear will become increasingly favorable for imbedded mesocyclones. Furthermore, the squall line has the potential (if enough instability can be realized) to become a broken line with supercells capable of producing tornadoes as the line races northeastward across central to northern and northeast Missouri into western Illinois.

 

[Andrew Pritchard]

Due to location restraints, I've really been pulling for the northern play in Iowa and Missouri. This looks pretty well shot however, with the current instability forecasts.

I'll continue to watch this system however, as the kinematics themselves warrant it. Large amounts of early morning convection are the culprit for putting a damper on the tornado chances with this system in the northern sector. Our biggest hope, is that this is being slightly over forecast, and that with the rapid deepening of the cyclone most of the early waa precipitation is quickly lifted northeastward out of the potential target area.

If this scenario is realized, I think northern Missouri would warrant some attention. Just ahead of the surface low and near the warm front, low-level shear profiles would lend themselves towards updraft rotation. Should early day convection be lifted out of the area soon enough, and some insolation can occur a broken line of supercells across northern Missouri southward does not seem unreasonable. The Chillicothe, Missouri area would not be a bad place to be in this scenario.

Just hard to accept a 500mb prog like this would go to waste.

http://weather.cod.edu/forecast/WRF/GL/wrfGL_500_spd_36.gif

Of course, this is hoping for a lot and going largely against what model data is showing. I think it warrants careful observation through tomorrow morning, however.

 

[Michael O'Keeffe]

I agree with Andrew on this one. The 4km WRF also agrees by breaking out several supercells near the Missouri River by early afternoon and then having a broken line of supercells track across N MO. The surface winds along the warm front are out of the SE creating very nice shear profiles as well but like he also said CAPE will be tough to come by with the morning convection but we shall see.

 

[W. Grant Dade]

I think there will be a chance of isolated supercells forming from Dallas to Greenville in north TX tomorrow afternoon and continue east across north TX. Shortwave moving in around 2PM and if we get enough sun instability may be underdone by forecast models. Still looking like one heck of a squall line will move through Thursday night.

I am thinking about heading to Greenville tomorrow afternoon and see what happens.

 

[Brandon Sullivan]

Due to location restraints, I've really been pulling for the northern play in Iowa and Missouri. This looks pretty well shot however, with the current instability forecasts.

I'll continue to watch this system however, as the kinematics themselves warrant it. Large amounts of early morning convection are the culprit for putting a damper on the tornado chances with this system in the northern sector. Our biggest hope, is that this is being slightly over forecast, and that with the rapid deepening of the cyclone most of the early waa precipitation is quickly lifted northeastward out of the potential target area.

If this scenario is realized, I think northern Missouri would warrant some attention. Just ahead of the surface low and near the warm front, low-level shear profiles would lend themselves towards updraft rotation. Should early day convection be lifted out of the area soon enough, and some insolation can occur a broken line of supercells across northern Missouri southward does not seem unreasonable. The Chillicothe, Missouri area would not be a bad place to be in this scenario.

Just hard to accept a 500mb prog like this would go to waste.

http://weather.cod.edu/forecast/WRF/GL/wrfGL_500_spd_36.gif

Of course, this is hoping for a lot and going largely against what model data is showing. I think it warrants careful observation through tomorrow morning, however.

I agree totally with Andrew, and I am adding Missouri to the Thread!

I see a shot at some tornadoes in the closer proximity to the low on central and northern mo.. enhanced low level helicity and excellent UA support, along with 50 kts of 0-6km shear would support this..

Of course it all contingent on any clearing that takes place.. 00z should tell a better story.

 

[Tim Marshall]

After looking at tonights NAM, looks like a negative tilt trough will blast through the plains tonight. I expect a squall line by morning across KS. Tornadic storms are likely to redevelop in the Ozarks on Thursday. Watch out central Missouri and NW Arkansas. Should be a MDT RSK or better. Bring your chainsaws. tm

 

[Bart_Comstock]

After looking at tonights NAM, looks like a negative tilt trough will blast through the plains tonight. I expect a squall line by morning across KS. Tornadic storms are likely to redevelop in the Ozarks on Thursday. Watch out central Missouri and NW Arkansas. Should be a MDT RSK or better. Bring your chainsaws. tm

Don't worry Tim, for the past few days I have been feverishly cutting down the trees in my county to prepare for this event. (for those who are geographically challenged Bentonville is in the most northwestern county in Ar.) For anyone wanting to chase in the Ozarks and wants someone that knows the area well I will be out chasing as this is my back and front yard. I really expect the show to start early in NE OK and still only see a few hour window of opportunity for isolated sups. The front will imo pass through Benton and Washington Counties around 7pm and the show will start in OK around 2pm. These storms are going to be flying so instead of a chainsaw you may just want to opt for a helicopter. Best of luck to anyone heading out tomorrow.