2/10/09 FCST: TX/OK/AR/MO/KS

[Chris Lott]

It looks like the GFS is starting to come more in line with the NAM in slowing the system down a little bit and not pushing so far east as before. Surface winds don't look as good, but plenty of deep layer shear. It looks right now like from SC and SE OK to NC and Central TX might be the place to be. Starting to show td's to 60 for Tuesday across C. and parts of NC TX.

 

[Andrew Stoller]

I agree. South central Oklahoma to north central Texas is the jackpot as of now. 60 degree dewpoints reach that area by 00z Wed, and there's a hint of a dryline bulge right on the border. The 12Z NAM is showing 1500 to 2000 J of CAPE juxtaposed with 400 to 500 m2s2 of helicity. The overall windfield doesn't look quiet as impressive as earlier runs - winds become veered out of the southwest by 950 mb, but the helicity is at least there unlike a few setups last year that had slight surface backing with imediate veering above the surface that produced line segments with weak mesocyclones.

The 12Z skew T for Ardmore looks pretty good after 00Z with a nicely curved hodograph, 81% supercell potential, 1300 J CAPE, and 3km EHI of 4.7.

There's a brief window for supercell development before everything gets undercut by the front.

 

[Danny Neal]

http://northernilstormchaser.blogspot.com/2009/02/update-21009-svr-wx-potential.html - Threw up my thoughts in an updated blog. Still like initiation to be around DFW stretching north to Mc Alester (area) near or just after dark.

 

[Brandon Lawson]

The latest model runs (assuming that the NAM is off its rocker), are not so promising, mainly showing the massive low on the Minnesota/Canadian border veering all the winds to garbage. And while the GFS is usually most accurate when it comes to shifting a potential Oklahoma/Texas chase into Arkansas, I still find a little hope in how the ECMWF still places the surface low in the northwest Oklahoma panhandle. Will wait for more runs and hope for the best.

 

[Brandon Lawson]

12z NAM is still holding on to what it has been showing the last few runs, with the shortwave firing convection along a well-defined, N to S oriented dryline, from Lawton, to Wichita Falls, to just east of Abilene, and this during optimal daytime heating and 60 degree dewpoints. It keeps the surface low in northwest Oklahoma as well, but you can see the 850 winds are already more veered than in previous runs in response to that enormous low in northern Minnesota. I hope it's not a trend. Ugh, I hate getting excited about these things, because I can feel the NAM shifting towards the GFS already...12z GFS will be out shortly and I'm really anxious to see what it shows.

 

[Donald Giuliano]

Quick glance at the 12Z GFS is looking more in line with the NAM, though there are still some issues with it trying to push the strongest 925/850 flow a little off to the east. As it stands, I'll be heading out, as it's hard to get a much better setup than this in the Plains in February. Here's hoping the NAM will verify.

 

[Mikey Gribble]

Not a bad looking setup for February. I just glanced over the forecast (I'm not quite into weather mode yet), but the setup looks OK for tornadoes.
The thing that bothers me the most is the veering low level winds from now until mid day tomorrow. Surface winds are southerly, but just above the surface at 925-850 they are veering pretty bad. The moisture over south-southeast Texas is plenty deep and would be great if it stacked up against the dryline, but I don't think it's going to play out that way. I haven't looked at forecast soundings (or much else to be honest with you) so I don't know exactly what to expect on the evolution of moisture advection, but I'm afraid the moisture along the dryline will either mix out or be shallow.

There are few things I hate more in this world than veering low level winds. #1 every time you are sitting around waiting for 850 to back it seems like it never happens in time. #2 it prevents you from getting a tight moisture gradient and quality dewpoints close to the dryline. #3 the wind shear side of it rarely works out well for tornadoes. It may make the SRH look great, but I can't think of hardly any good tornado days where the 850mb winds were veering.

Not to say that will necessarily be the case tomorrow. The NAM does show 850mb backing pretty good during the afternoon, so the shear along the boundary should be fine. If you get sufficient moisture along the boundary or if storms can realize the better moisture out over the warm sector then I think we'll get some tornadoes.

edit - my target would probably be Graham Texas as of now

 

[Chris C Sanner]

Well "surprise surprise", looks like the GFS is trending back towards the NAM in terms of westward placement for a second system in a row

IMHO, this looks like it is going to be a Gulf coast-ish type of severe weather event (at least in the classic sense). There’s going to be a main squall line form back to the west with some embedded sups and areas of rotation and such while in front of that in the grungy stuff there will be some rotating “discrete” supercells.

So the question then becomes…do you throw a dart at the wall and hope to pick a good target in the warm sector or do you sit east of the dryline and pray the forcing is weaker than forecast and you get a broken line of supercells? Tough forecast for tomorrow, these early systems never are easy for sure and it definitely won't be easy chasing if you decide to go out tomorrow for sure with fast storm motions and tough terrain.

More on the blog too:
http://www.supercellhunting.com/?p=88

 

[Jason Harris]

Doesn't it seem like right about the SE border of OK with TX would be a good spot to be? Not only the MOD risk there from spc (first of season?) but also the warm front will be there in about 24 hours.
http://www.rap.ucar.edu/weather/progs/index.php?prog=24
CAPE would be moving in nicely:
http://www.emc.ncep.noaa.gov/mmb/namsvrfcst/
And Norman, Ok Hazardous Outlook for SE OK mentions better vertical windshear.

Could always drive on East to AR or LA but aren't the viewing conditions less good there?
*Ah, I see there's now a whole thread about how driving in SE OK sucks.

 

[Jeff Richardson]

"Could always drive on East to AR or LA but aren't the viewing conditions less good there?
*Ah, I see there's now a whole thread about how driving in SE OK sucks."

Yes it does...AR & LA would be no better.

Would not surprise me at all to see a few supercells form in the evening, but a squall line/lewp scenario being the dominant storm structure. I'm experimenting some on this forecast and trying more hand analysis and a little less attention on the models. Time to sharpen the colored pencils!

 

[Mikey Gribble]

That is all brutal chase country Jason. You can give it a go if you want, but the road networks aren't very good and there's quite a few trees and hills (depending on where you are exactly). I don't know how early storms could fire over the warm sector so you may not get much time to work with either before dark. The wind shear will be better in that area though.
I would go with the dryline and park yourself between Dallas and Ardmore and hope for a discrete storm down there. Honestly unless you live close I would be sitting this one out. I do think there is a decent chance of a few tornadoes, I'm just not convinced they are going to be chaser friendly.

 

[Brendon Lindsey]

Forecasting Question for Feb.10.2009

Well I have started to do more and more of looking at the models myself and if the GFS was to verify tomorrow its showing storms breaking out SC to C Oklahoma before Hell breaks loose down south of there. They would be working with 500-1000KJ CAPE and be closer to the Low. What would keep those from becoming supercelluar. Also is there any play for developement in NE OK with the low/cold front/warm front/ (dryline shortly behind) for forcing mechanism? Just wondering/ hoping to learn a few things.

 

[rdale]

I'm not exactly sure what you are asking - one thing you can do is read the SPC's Day 2 outlook since they refer to NE Oklahoma, and I'd also suggest the forecast discussion (AFD) from the Tulsa office.


MOD NOTE: This post is being allowed in this thread. It's from a thread I merged with this one. Nobody needs to report this post. Thanks. --Chris N.

 

[Chris Wilburn]

If I were going to chase (not sure yet) I would target from say Gainsville to Waurika. Both cities have good north/south and east/west road option. I agree with Mikey on this one and I have chased my fair share of SE OK to do it again. I think the best play may be to get discrete cells from Dallas to Ardmore or points slightly to the west early in the game and go from there. I too noticed the veering of the 850mb winds which I really don't like, however moisture and CAPE look good (depending on how late the moisture arrives.) This isn't a bad setup at all for February. Obviously the sun goes down fairly early so sunlight as always is an issue with these early setups. If you are eager to chase and are in somewhat close proximity to the target area I say go for it. Low 50 dews are present in the Dallas are at the moment with mid 50 dews in eastern TX. The new model runs come out very shortly so we can see what they show.

 

[Eric Sipes]

I'll be out tomorrow, I'm too close not to. I'll be targeting the dryline in NW Texas, SW-SC Oklahoma. The stuff in SE Oklahoma looks interesting but, it'll be a late show. That coupled with the sorry road network and storm speeds of 40knts, it'll be next to impossible to chase. There could also be a punch of dry air in that region killing any and all chances.

I like the fact that mid 50s to near 60tds will be reaching I-44 by 21-00Z along with CAPE of 1000-1500j/kg. Shear should also be "decent" in this area. The aformentioned 850 winds and Hodos are the most concerning problems with this setup. My only hope is that we get some nice sups before it transitions to a squall line near sundown.

If the current models verify, I will target around Waurika and adjust from there. Although, if trends continue, the new models may also slow the system down putting the dryline along an Altus to Seymour line. That would move my target to the I-44, Hwy 70 intersection. In any case, I'd like to stay North of the Red River. Every chaser knows how hard it can be chasing a fast moving storm across the river.

-Eric

Edit: After the latest NAM runs, I'm not so sure. It did the opposite of what its been doing and pushes the dryline east to I-35 by 00Z and into horrid chase country. I'm gonna have to wait until tomorrow before I make my final decision.

Edit #2: 0625Z, Now the new GFS has me hangin' onto some hope. It did exactly what I thought the NAM would do. It pushes the dryline further west with a nice bulge W of SPS. It still has some of the same concerns but with MUCH better chase terrain. Then again, I could just be wishcasting again.