2/27/11 FCST: KS, OK, TX, MO, IL, AR, LA, MS

[Tim Supinie]

Agree with the moisture bears here. Front is clearing the Gulf Coast, which is really bad news for an event in just 48 hours. We would want the front to stall in Texas, which would lead to quick and excellent moisture return. Not the case today. I believe even Deep South Texas will dry out later today.

Ah, yeah, we may have to deal with that. For what it's worth, the surface winds in deep south TX have turned to the east as of 19Z, suggesting that a return to southerly flow will happen soon.

Beyond that, not much else to say, but I am concerned with what has already been mentioned: namely, that the cap holds until after dark, and initiation occurs in eastern Oklahoma after sunset. If moisture returns as progged, I think we'll be fine with initiation right around 00Z. If not, the warmth in the low-levels will probably keep initiation until synoptic-scale lift erodes the cap after sunset.

 

[Mike Johnston]

I'm not really concerned about moisture return. The Gulf isn't exactly being scoured out...even now, winds are light and variable down there. By tomorrow evening, 60 td's are being progged as far north as the Red River. Yeah, there's a nominal cold front, but don't take the Norweigan school too seriously at this time of the year....sun angles better by the day. As for the cap on Sunday, it's a definite factor, but take a look at the models and see that maybe the area around Great Bend, KS could see some development.

 

[Ryan Wichman]

With the dynamics in place and the timing of this storm I would not be shocked to see this turn into the first real big outbreak of 2011. The ruling is still out if that means a lot of tornadoes, but everything I can tell from this far out is point towards a large overnight severe threat. Kinematics and wind fields throughout the whole warm sector layer would point towards a big high shear/lower cape outbreak overnight Sunday and through Monday morning. The verdict is still out on the details but all signs seem to be pointing to a large overnight severe weather threat for a large portion of the mid-Mississippi river valley and into the Ohio river valley.

 

[Trey Thee]

With the dynamics in place and the timing of this storm I would not be shocked to see this turn into the first real big outbreak of 2011. The ruling is still out if that means a lot of tornadoes, but everything I can tell from this far out is point towards a large overnight severe threat. Kinematics and wind fields throughout the whole warm sector layer would point towards a big high shear/lower cape outbreak overnight Sunday and through Monday morning. The verdict is still out on the details but all signs seem to be pointing to a large overnight severe weather threat for a large portion of the mid-Mississippi river valley and into the Ohio river valley.

It does seem to be pointing that direction. I'm still hesitant about instability over eastern OK...I guess I'm in a "I'll believe it when I see it" mode with this system. Looks like SVR will be likely in the eastern half of the state but what mode and what intensity and coverage I just don't know yet.

It definitely appears that later in the evening and overnight Arkansas and the areas you mentioned could see a substantial nocturnal event. I'm expecting to wake up tomorrow morning with an MDT in place from just east of I35 back into central Arkansas running from just south of the Red River north to the OK/KS line if the models hold together.

 

[RMacDonald]

Right now I am tracking the initial threat areas in E OK to SW MO, with another area in NE TX to SW AR. With the highest area right now centered over SW MO areas with LI's -4 to -5 and SFC Cape Value increasing to 1K. Overall still not totally convinced on how the event will unfold. Here is the graphical breakdown on initial locations.


http://smartwxmodel.net/severe.pdf

 

[Connor McCrorey]

I usually hate it when people post nothing more but a link to a forecast on their blog, but... http://www.texasstormchasers.com/2011/02/26/sundays-severe-potential/

I'm remaining hopeful for a storm or two off the dryline before sunset. Any storm that goes should have what it takes to produce if the cap can be broken.

 

[Trey Thee]

Looking at the models and data this morning I'm wondering if the slow down we've seen will continue. Anyone else wondering if we could see convection as far west as US 81? If the trends continue that would seem like a distinct possibility and could put the OKC metro under the gun. Convection could potentially initiate west of OKC if something can break the cap prior to sun down. Given the dynamics if we get moisture in place, I would expect those storms to turn severe relatively quickly.

I am also a bit surprised we did not see an MDT at least for points east of US 75 this morning. This event could be quite nasty as you get east of 75 especially into Arkansas and southern Mizzou.

Some of the upper air dynamics don't really seem to fall into place until after 6pm. If the system does initiate in the I35 area by 4 or 4:30 PM and push east we could have a substantial tornado threat over Eastern OK just after sundown. Another issue is when the cap erodes will we just see the system go linear very quickly? Lot's of issues yet to be worked out.

 

[Mike Smith]

Based on the new NAM, given convection, the corridor from just south of ICT to Perry looks like a favored area for tornado development from about 5pm to 9pm. My one question is whether a circulation could make it to the ground given the potentail for elevated supercells.

 

[Donovan Gruner]

Looks to me like the GFS is showing a cap breach between 18z and 21z right over central OK. IMO the best place to catch some diurnal/discrete storms would be mid to late afternoon along or ahead of the dryline somewhere in C OK. Any further east, and you might be chasing at night, and likely something similar to Thursday night. May have a similar QLCS type event as we move into the night.

 

[Zack Cooper]

SPC just went with a large Moderate Risk area... I do think tomorrow has potential, but the question is... "will the cap break in time?"
Based on the 21Z SREF... i think it is going to be a close call... but once storms do form, they may be intense. Cape values over 1000 j/kg and decent moisture return look to be present. not to mention 60-70kt effective bulk shear. I think a strong tornado or two may be possible tomorrow given helicity values to 300 m2/s2 and nice LLC. SREF paints an area of 20 STI, albeit mainly around and after 0Z. Overall, storm mode appears questionable and whether storms form before dark or not is iffy. So I wouldn't make the somewhat long drive for this setup. If i were to chase, it would probably be in either South Central MO or Southwest MO. Good luck to everyone going out!!

 

[Fritz Kruse]

Based on the new NAM, given convection, the corridor from just south of ICT to Perry looks like a favored area for tornado development from about 5pm to 9pm. My one question is whether a circulation could make it to the ground given the potentail for elevated supercells.

I also like the area between Wichita and Perry along the warm front. Any supercell that initiates along the dryline then rips northeastward and crosses the warm front could quickly go tornadic. That area near Enid to Ponca City looks like particularly good going by the NAM.

 

[Andrew Ryan]

Interesting setup for tomorrow. A lot of people have been focused on the cap and rightfully so. The lack of instability shown on the models will cause any storm to struggle in the strongly sheared environment. The wind shear is not nearly as strong as it was progged early by the models but it's still strong consider the meager CAPE values being displayed. However, I believe the CAPE is being underdone. I think that the temperatures are being slightly underdone and the quality of the moisture is not fully realized. The models are not fully picking up on the terrain-induced LLJ tonight. The combination of these two factors, IMO, should up the CAPE values to more manageable levels. I talked about this more in-depth in my blog post: http://bit.ly/h9Ly7j

 

[Eddie Natenberg]

Ok, I was pretty impressed by the run to run consistency with this trough. It has the thermodynamics and forcing for a pretty good night time event. Deep layer shear and moisture look impressive. But the amount capping and forcing needed to break the cap may not begin till evening. I would definitely be concerned for sig svr overnight. A strong low level jet may help parcels stay surfaced based which increases the chance of night time tornadoes. Bowing segment and flooding become an issue farther north along the warm front in MO/IL as the wave ejects out. The western part of the moderate risk area will have the best setup as the jet max approaches aiding in initiation and should have better dynamics for isolated storm modes sometime around 1-2 UTC. My target would be in the central part of TSA CWA east into AR sometime around 3-4 UTC has the best potential for sig svr. Hmmm I wonder what the hrrr will say tomorrow about this.

 

[Marcus Opitz]

I'll throw my .02 at this.

Feel that SBCAPE-Shear and dewpoint(per 30 hour GFS) could provide the greatest wind damage potential in the SE KS and SW-SC MO corridor. Still think the main show (mature bow echo action) will occur late tomorrow night as the strongest mid to upper level winds arrive. Think storms will initiate late eve in SE KS, NE Ok and go linear very quickly. I must say I am biased to the SW MO area for visibility purposes.

 

[RMacDonald]

Just updated my graphic forecasts for the severe weather event in OK-AR-MO, right now seeing the highest threat in the E. OK-SW MO-W AR. Seeing some good shear and CAPE values, I believe will see Isolated Tornadoes in this regions.
http://smartwxmodel.net/usa.gif