4/02/11 FCST: KS, OK, TX

[Doug Drace]

Not going to go crazy on a long forecast 5 days out on this one with the GFS being less than reliable from this range so far in 2011. However for 2 days now there has been relative consistancy, on Sat 4/02 for Western Oklahoma, Southern Kansas and NW Texas. Generally around 1500 J/kg MLCAPE the length of the previously mentioned region, some impressive bulk shear, high Theta-E, DP's 60-65 along with large curved Hodo's, especially in Western Oklahoma. The one big stickler so far, if models can maintain this one all the way to the day...is a very stout Cap. That's really all I want to say on this one right now, forecasts can be more in depth later on if the models can remain consistant closer to the day. Sun 4/03 looks pretty sweet as well, but how far east in the sticks will that day be???

 

[David Mayhew]

Yeah, I've been watching that too. 500mb winds are looking more favorable on today's run. Moisture still keeping a little East (I'm in CO, so further West would be preferable).

 

[Skip Talbot]

12z run just came out. That cap is a show stopper. I also fear the GFS is way too bullish on the amounts and northward progression of moisture return. Compare the NAM and GFS out to 84 hours and you'll see significant differences, just as we have on the last few setups such as March 28's non event. Saturday is looking like a non event at this point or perhaps an isolated chance of severe south of the Red River where those 60+ Td's are much more likely to wind up. But with the GFS being too progressive like usual don't expect those midlevel winds to pick up any or that cap to weaken.

 

[Doug Drace]

I totally agree Skip, the cap looks like it could be a major show stopper on this one, and I totally agree about the bullishness of the GFS on moisture return so far this year. I simply wanted to put this one out there with so many other factors looking quite nice....so far. I am approaching this one with only a slight amount of cautious optomism to this point. the NAM solution will likely prevail again, as it has by far been the most consistant model with severe events so far, but the southern plains west of I-35 is bound to crank something out in the relatively near future (next 2 weeks or so)...its just climatologically time for something to get crankin in the True Tornado Alley, where a chainsaw and an airplane isn't required to see a decent supercell/tornado. And yes David...WEST is BEST! Here's to hoping

 

[jamesmseitz]

Looking at this I am going to disagree. Here is my case. 4-6 runs ago CIN was at 300-400 now its 100-150 so GFS has been backing off for awhile. CIN of 100 or so is doable and will keep cells discrete and with the shear being a good as it is with the Bulging dryline and backed winds so a eroding cap seems more likely. GFS has also been off on both of these features all year (Cape and CIN). The temp is forcasted to be around 8 C at 700MB and basing of Davis cheats that is strong but breakable Cap. The Vertical Velocity is strong alone the dryline so forcing seems to be in place. As stated before the Hodos are great so the storms that do get up will be beasts. I for one, believe this is the first outbreak for the S plains of the year.

With all that said when the day come Cape will be most likely 2500+ and the cap will break. My guess is Helicity will reach 200-300 and EHI will be at least 2. In my eyes right now everything seems to be in place. I do nopt trust GFS to handle any of these except to show the pattern change. The formulas they use for it that seems to be all they are good for now. NAM gets this is 24-30 hours and if it says CIN off 200-300 then I will worry

 

[Brandon Sullivan]

12z run just came out. That cap is a show stopper. I also fear the GFS is way too bullish on the amounts and northward progression of moisture return. Compare the NAM and GFS out to 84 hours and you'll see significant differences, just as we have on the last few setups such as March 28's non event. Saturday is looking like a non event at this point or perhaps an isolated chance of severe south of the Red River where those 60+ Td's are much more likely to wind up. But with the GFS being too progressive like usual don't expect those midlevel winds to pick up any or that cap to weaken.

Skip makes very good points, and that 84 hour comparison was the first thing I looked at... Like he mentioned, Mon March 28th looked like a significant event, but turned into a moisture starved and capped mess.. The NAM when it was in range showed this from the start.. The pattern of recent has been killing the gulf every few days, not allowing for significant moisture return to commence.

Looking at the 18z products, there is still a very large spread in the GFS and NAM, and sadly I have a tendency to believe the NAM... There will not be any storms with a cap like that.. Even if a weaker cap shows up, a large amount of forcing would still be needed, which you wouldn't get until that UA energy finally moves into the plains..

Sunday/Monday if anything have more potential in my mind..

 

[Donovan Gruner]

At this point I would honestly be surprised if anything happened this weekend. As far as things look on the basic synoptic scale, there will be a cold front moving down toward the GOM Friday into Saturday, which will most likely choke off most of the moisture return that the GFS has showed. Even if the GFS did verify, like Skip and Btsull said, it is likely the cap will stop most if not all development from occurring. Believe me, I would absolutely LOVE for the cap to break on Saturday. It could absolutely be a good day if there is ample moisture return and cap is able to weaken, but I just don't see it happening at this point.

 

[Doug Drace]

After looking at the 6z NAM out to early Saturday afternoon, im in total agreement that once again GFS has been way too agressive with moisture return and CAPE for Sat 4/02. This looks just like the last one for the 28th, with the main difference being that this mornings GFS run has come more in line with the NAM much quicker this time out to 84 hours. Saturday looks pretty much hopeless now, with the exception of the I-20 area in west-central Tex...MAYBE, and thats only going to be with questionable Td's when comparing the NAM/GFS out to 18z...and further removed from the better upper support to the north. The Fri CF does appear to be the major player on this event going into the toilet, and I don't believe the GFS picked up on it or handled it very well in earlier runs. Sunday 4/03 looks a little more promising, however the chase area is a lot less desirable....again....it looks like if we are going to see any kind of significant severe in the southern plains, it's going to be an I-35-to-the-EAST chase scenario. Im rapidly beginning to remember why I despise LaNina...whether it's supposedly diminishing or not!

 

[Brandon Sullivan]

Just posting a quick thought that I just posted to my Facebook...

From 12z NAM..

Kinda funky synoptic setup for the upcoming weekend.. Semi nw mid level flow, a sharpening dryline across TX.. Southeast flow from SFC to 850, then west at 700... Not sure just what to think yet.. Maybe a slow moving supercell across North TX on the southern edge of Mid Level Flow, but hard to find tornado potential in that setup at this time.. Lots of good instability and surprisingly optimistic moisture return forecast, so we can see where this goes.. Better low level SRH across the caprock area, but no potential to break that cap, at least off the 12z NAM... Being on the periphery of UA flow, especially NW is not going to help break a cap like that.. Definitely need significant forcing, and upper air factors to overcome that!

 

[Aaron Dooley]

12Z GFS/NAM

NAM has better CIN #'s then the GFS does but both allow for some holes where CIN is much more breakable. The only problem right now it that the NAM is favoring a more southern target(limited northern extent of moisture return) around San Angelo to Abilene and the GFS is showing a more north target around Vernon to Wichita Falls. Assuming both somewhat meet in the middle or that the NAM will be more true given recent events with GFS this far out you can probably safely assume the trends of less cap and slightly further south target will dominate. Given this, and the fact we are still three or so days out, I feel like it is worth watching and possibly tentatively prepare for a jaunt north to the Abilene/Munday area. Based on the last few systems though it needs to improve more to get me excited. Saying this, the hodographs are quite nice on both the GFS and NAM if something were to go up. Sunday/Monday need to be watched as well.

Just posting a quick thought that I just posted to my Facebook...

From 12z NAM..

 

[Doug Drace]

Yeah I just looked over both the latest runs of NAM/GFS, and I concur at this point that maybe....just maybe this one isn't dead yet...paticularly in that general area of I-20 around Abilene. Suprisingly the latest NAM is more in line with previous GFS runs...but the CAP will be the biggest player on this one IMO. Wait and see for now....Sun appears much more impressive along and east of I-35...who knows right now...keep an eye on things and we might get pleasently suprised saturday...

 

[Stephen Jones]

Yea, I agree.. Even though today's 12z Runs actually looks a little bit better synoptic wise.. It still brings in very warm air at 700-850mb. It is gonna be very tough to break this cap on Saturday unless the cap is weaker than expected.. But with the amount of forcing we are dealing with, it will still be very tough to get a parcel to break through this cap.. CINH is upwards over -200 to -300 along most areas of the dryline.. I feel that dryline bulges will be key and if a storm were to break the cap, it would have a very tough time sustaining themselves. We shall see as there is lot of time for this to change.

 

[Doug Drace]

This day continues to look as though it would be very chaseable if not for the #1 detramental player...the hellacious CAP just ahead of the DL. NAM/GFS both continue with remarkable agreement for once in reguard to the overall synoptic solutions 3 days out. CAPE looks nice from NW TX into SW OK generally in the range of 1500-2000, and the 06z NAM is putting out some mouth watering 0-3km Helicities through that same general area. Td's 60+ are easily making it to the OK/KS border, with a couple of models (mainly GFS) still showing somewhat of a DL Bulge in NW TX, to extreme SW OK as the DL mixes slowly toward the east by 0z. In reguard to the nasty CAP, the one area it does appear to have less of a stranglehold is in that NW TX/SW OK area near the potential DL Bulge. 06z NAM for 0z Sat CIN is in the -5 to -40 range, with a couple of tiny pockets at 0. If that were to veryify Sat, it's certainly probable for something to go up in that localized area, however the CAP rapidly strengthens just around 30 miles or so to the east around SPS to the -100/-200+ range. So im not quite sure if a storm went up, how long it would be able to survive and thrive in the stronger capping environment east of the most likely initiation zone. Somewhat suprising to me is it's actually the normally more generous GFS that has the CAP stronger through all of NW TX/SW OK near the DL Bulge from -100/-200+...still not completely unbreakable, but less favorable than NAM for sure. Everything else seems to be in place for Saturday 4/02 IMO. We still plan on heading out and at least getting a good tan on near the area where the greatest forcing would likely be, generally around Seymour, TX...tentatively ATTM...and try to squeeze a 2 dayer out of this with Sun 4/03 looking a little more promising closer to the I-35 cooridor.

 

[Doug Drace]

12z NAM 4/02...gotta like the trends in NW TX with each run so far. IMO the CAP looks more breechable 4/02 than 4/03, at least with the OK/TX portion of the outlook. Even though 4/03 certainly has better overall dynamics to work with over a much larger area. There are some nice trends im seeing that favor the more localized "day before the day" potential of Sat 4/02, with the small possibility of an Isolated Supercell or two. Personally I kind of like a lower end risk sometimes (when they pop an isolated storm), helps keep a large part of the chaser circus at home

Pro's:
1-More localized and chaseable area
2-Strong CAP, but not as wicked as 4/03...ie: the -10 to -50 CIN for a few runs now in WC/NW TX near DL (small zone but consistantly there)
3-Consistantly forecasted DL Bulge NW TX
4-Very Favorable/Strong 0-3km Helicity values
5-Large curved hodo's
6-Moderate to High Instability
7-60+Td's
8-Run to Run Model Consistency both NAM/GFS

Cons:
1-Less Upper Support
2-Less Forcing along DL, with exception of NW TX along DL Bulge, if it verifies
3-CAP Strength 20-40mi east of DL
4-NO models have broke out any precip in NW TX/SW OK for this day
5-Decent Probability of a complete CAP BUST!

12z NAM Output: (GFS is relatively the same, with more CIN generally -150+ in same area)

 

[Aaron Dooley]

I do see one notable difference...It appears there is lack of forcing behind the dryline, not compact moisture gradients, etc so we are probably lacking a trigger in addition to the cap. The winds to the west don't appear to provide any forcing and in fact later that night it looks like the warm front retreats the dryline and there is initiation from this. That could be Sunday going into Monday but I think it is in fact Saturday night going into Sunday I saw this. I'll post shortly with attachments.