2011-04-22 FCST: OK/TX/KS/MO/IL

[Doug Drace]

Friday is shaping upto be an interesting day across OK/N TX/SE KS/MO. Due to our preferred chase area, will focus my forecast on the OK/TX portion of the risk area. It's a little difficult to pin point things right now with NAM and GFS varying placement of the DL/CF/Triple Point. Overall placement issues between the two have NAM placing the boundries closer to I-35, GFS more in Western OK. Certainly the W OK scenario would be nicer, as we havent had anything in the way of severe wx out there all season, and it would finally give everybody a break from the rugged chase terrain E OK...even though that area as been very fruitful of late. Either way, its going to be a day of high cape 3000+ j/kg along the DL, a 50-55 knt H5 flow, along with 60's Td's along the DL in W OK GFS, C/SC/E OK NAM. Both models forecasting large curved hodo's east of their forecasted boundry positions, with NAM completely removing cin in the area near the Triple Point from C OK to SC OK, GFS indicating more of a cap, yet still breakable from SW OK through C OK. EHI's 0-3/0-1 look really good, especially just SE of where the TP ends up. Even though SPC has a much higher probability 30% Hatched in MO, NE OK, I greatly prefer to take my chances along the DL in OK, as I have had little success with CF Supercells producing before rapidly being undercut.

 

[Brendon Lindsey]

Had my eye on this since Sunday. I'm hoping for this 12z GFS to verify, I would put myself in Duncan , OK . The sounding looks superb. Just feel like sharing the Skew T for Duncan, I dont know if this is time sensitive but probably is. http://beta.wxcaster.com/cgi-bin/parse_skewt_trace.cgi?model=GFS&fcsthr=060&STATIONID=KDUC I have never really been succesfull on a CF play. So I am banking for a nice triple point setup in Western Oklahoma.

 

[Doug Drace]

Yeah Brendon I completely agree with what you have said on this one. If the GFS verifies the Lawton to Duncan, OK areas look really nice. LCL's are pretty low through there as well in the 1000>less range, with big looping hodo's. It would be a nearly perfect scenario with the Triple Point just NW of there in W OK.

 

[Greg McLaughlin]

Looking at the forecast sounding for Duncan, I am not liking the LFC there, but its too early to take all of this literally. A lot will change. Its nice to have deep moisture in place over Texas and we don't have to sit around with our fingers crossed the day before hoping the moisture returns in time as the Gulf recovers. Even if this weekend doesn't pan out with a nice tornado setup or two, the much needed rain will hopefully help out the drought for parts of the southern Plains.

 

[Jim Parsons]

Can we add IL to this thread....Setup for southern IL is starting to look like last Tuesdays warm front/triple point setup.

 

[Skip Talbot]

It is a similar pattern to Tuesday in IL. The major are differences I see are forecast instability looks to be about half what it was on Tuesday across the warm sector. The warm front also looks to be less defined. I'm not sure I'd gamble with playing the warm front tomorrow like I did on Tuesday (and ultimately that was a bad call too as we wound up hauling butt west back to some storms going up ahead of the cold front), as the shortwave is well off to the west over Missouri and forecast instability is substantially lower than it is on the cold front in Missouri. I'd probably play the triple point in Missouri if I were chasing tomorrow and try to catch something going up on the cold front as it moves toward the better directional shear on the warm front. This would be a similar situation with the storm that produced the Bowling Green, MO tornado on Tuesday. I'm not chasing tomorrow, however, due to work obligations as I already took Tuesday off to chase and since this setup looks more like the runt version of Tuesday so take my negative bias into consideration. Forecast instability appears to be low due to large amounts of crapvection hanging around in and north of the warm sector. If tomorrow morning there is good clearing, however, expect portions of eastern MO and southern IL to destabilize much more than advertised and for that warm front to be in play. 1km storm relative helicity is very impressive by the warm front so if the sun does come out in southern/western IL tomorrow, watch out as there could be some IL warm front magic and more tornadoes.

 

[Doug Drace]

Im still liking the area south of I-40 and west of I-35 generally around the Duncan to Ardmore, OK areas in SW/SC OK along the Dryline. It still appears there will some form of a Triple Point setting up just west of the OKC Metro area by 18z tomorrow, NAM/GFS are both now in relative good agreement. GFS is more generous with LCL's around 1000m>less, where NAM is more in the 1500m range through the same area. Both models are indicating a High Cape Environment over 3000 j/kg from generally around Chickasha to Lawton to Wichita Falls over to I-35. Cin is almost neglegable along the DL per NAM, still hanging around per GFS but not more than around -50, so the cap still seems breakable. Nice area continues through the same zone of 0-3 EHI's, along with, not incredible, but still decent 0-1 EHI's and nice curved hodo's. IMO the biggest challenge to overcome will be overall convergence along the DL with the more significant forcing being further north, even so both NAM/GFS show LI's from -5 to -8, which may prove to be just enough to get a storm up that would likely be quite rewarding!

 

[John Farley]

Big differences between the evening runs of the NAM and GFS on the IL/MO aspect of this setup. NAM has the surface low/triple point a little SW of Quincy, IL, while GFS has it well to the northwest of there up in central IA (though perhaps somewhat occluded). Consequently the warm front is a lot farther north on the GFS suggesting the best play might be slightly southeast of the Quad Cities, while the NAM of course has that front much farther south, closer to the I-70 corridor with generally sharper baroclinity in the eastern half or so of the state. I think the target is clearer if the GFS verifies; if the NAM verifies it could be a tough choice between the sharper baroclinity around, say, Effingham (but also more veered surface winds) and the better directional shear and proximity to the surface low up somewhere in west-central IL. Both models have CAPE in the roughly 1200-1800 range in the warm sector, not great but probably enough for a tornado or two with the wind shear and dynamics of this system. I suspect that how long the clouds and rain from overnight linger, and where they linger, will be a significant factor shaping which model comes closer to reality. Either way, there is a warm front in Illinois, something not to be ignored. However, the window may be short and small, with the forcing on the cold front and the increasingly veered surface winds as you move southeast from the surface low, wherever it ends up.

 

[Von Castor]

On the southern end of tomorrows risk area is anyone else concerned about the 850 winds at 18z tomorrow bringing in dry air from the wsw? At 0z they are forecast to be back around to the south but that may be to late. Damage may have already been done.

 

[Doug Drace]

Just looked over the WRF Hi-Res for OK, nothing but a linier mess along the front, and nothing fires along whats left of the DL in SC OK. Latest model runs look a lot less enticing, with higher LCLs, and yeah im concerned about the 850's. The whole setup has trended to linier overnight with the hodo's losing all those nice arching clockwise curvatures. Just dont see much in the way of tornadoes today, in OK....buuummmmer!!!

 

[jeremy wilson]

Southern Oklahoma or East Central Oklahoma? Hmmm. Hrrr showing a cape bomb going up in southern Oklahoma this afternoon near the CF/DL intersection with what looks like a mess getting undercut further north. Spin definitely gets better further north though. Think I'm gonna stay south and rely on instability magic today. Caught a nice tube north of Abilene yesterday in way less of a favorable environment than this so my hopes are high!!

 

[Brian Mette]

The SPC has upgraded today to moderate risk.

The latest model runs actually show what looks like a couple of isolated supercells developing down in SC OK/NC TX. NAM is even showing 4000 j/kg CAPE in SC OK. I think there may be a decent chance for a tornado or two to form. I may have to make a trip down to Lawton today.

 

[Andrew Revering]

TornadoTarget.com, which attempts to predict tornadoes on a localized scale, is showing a tornado near Checotah, OK about 6:15 p.m. That forecast was made at about 10:20 a.m. this morning. We'll see.

This forecast utilizes high resolution modeling with some proprietary inserts and a couple proprietary indices to come up with that forecast.

FYI... 0118 ONAPA MCINTOSH OK 3541 9555 SEVERAL TORNADO TOUCHDOWNS WERE REPORTED NEAR ONAPA. SOME TREE AND POWER LINE DAMAGE WAS REPORTED IN THE AREA. THIS IS A PRELIMINARY REPORT. ... this is 2 miles south of Checotah.

 

[Doug Drace]

Im liking the SC OK area as well with HRRR firing off potential supercells from around Ardmore to Marietta OK. Off work at 3 so shouldbe in good shape if something goes up. Better shear certainly NE...but SC SE OK has been a hot bed of late...

 

[John Farley]

Regarding the MO/IL area: I would have thought with all the clouds, rain and hail, and resultant cooling in the STL area around mid-day that this area would be pretty cooked for any chance of severe weather. However, the HRR and RUC still insist on advecting 2000-3000 CAPE back up into this area, a process that already appears to be under way per the SPC mesoscale analysis page. Triple point appears to be tracking to somewhere near Bowling Green or Hannibal, MO by 5 or 6 p.m. If it really does destabilize as much as the models think, then I think there could be a chance of tornadoes near/a little southeast of the triple point near the warm front, probably in reasonably chasable terrain in southwest IL. If it does not destabilize that much, then the better outlook would be in the southeast half of MO, which for the most part is nearly impossible chase territory. SPC currently has MD out for most of MO southeast of I-44, up almost to the STL area. A slight northeastward shift would put southwest IL in play.

Edit, 2:30 p.m. - I am becoming increasingly interested in the area between STL and COU. Looks like high CAPE is advecting into this area, and not sure if storms will make it to chasable terrain in IL before dark. This part of MO isn't great chase terrain, but it is not awful, either.