4/9/08 FCST: TX / OK / KS

[Jordan Hartley]

I know ill here about how this is seven days out and I probley have no buisness starting a FCST thread with my limited knowlege in forcasting but what the heck this is one I know I will be able to chase if everything goes right with this next system so here it goes. GFS@180hr showing a strong trough that will move threw the plains on Wednesday. So much can change between now and then but as it stands a possible dryline setup will come into play across much of C OK and N TX. 850mb winds are veering slightly but maybe if I cross my fingers that will change in a week or watch this whole thing turn into nothing but wasted time and hope hehe. Tuesday woudnt be so bad if we could get better moisture return which is why im looking more towards Wednesday. Shear looks great on tuesday but moisture isnt that great. Wednesday has much better moisture but directional shear starts lacking a bit. Just have to wait and see not much more I can say.

What are better days to chase? Shear>Moisture or Shear<Moisture?

 

[Dallas Smith]

I agree Jordan, this is a long way out. However, I am not chasing tomorrow (4/3) so this appears to be the next best chance for a decent storm system. I appreciate the start of the new thread! With that said, I am not real impressed with the 500mb PVA, as well as, the directional shear. Speed shear is decent across the OK/KS region but I am not impressed with the overall pattern. Currently, the GFS is forecasting a 990 low in the SW portion of Kansas with a secondary low forming in the NW portion of OK. Looking at the forecast soundings, one aspect that is concerning is the stout cap that will be in-place till around 9:00pm. With decent CAPE, shear and low level convergence close to the low, convergence may break the cap before sunset. This will be a system to watch over the few days.

 

[Mikey Gribble]

Finally a classic spring tornado setup for the plains. It seems like the same story with every one of these. The first day (or day before the day) is always lacking slightly on moisture and the cap is an issue, but directional shear is great. The second day (main severe wx event) has more speed shear, less directional shear, better moisture, and the cap is no longer an issue. Well the cap looks like it might be an issue according the GFS, but I would bet money that will change. Right now the biggest problem is a lack of insolation over the warm sector with temps only reaching the low 70's over Kansas, but there's no reason to dwell on details this far out. The bottom line is we have a synoptically evident severe weather outbreak showing up on the GFS. What more can we ask for?

 

[Mike Smith]

The Japanese model (per AccuWeather Pro) is extremely impressive with this next system.

There is a 997 low on the border WSW of GAG at 12Z April 9. At 12Z on the 10th, there is a 982 (! for April) low in SW Iowa.

The shape of the system and its evolution resembles April 3, 1974 except that it is farther west.

Of course, this far out this is nothing more than interesting speculation.

Mike

 

[Kenny Drake]

I can't help but notice how well the Ensemble members agree with this system. Oh man...

I would post a forecast but all I can do is about what the HPC does... look at ensemble members and look @ spread. I see little spread with this monster trough. Usually when you see a wave of this magnitude the details do not matter. I think the current ensemble output compares well with the April 3, 1974 outbreak. Of course this is a week away, but my eyes are all over it.

 

[Dann Cianca]

So nice ... coming through all negatively tilted and angry looking. Might be my first chance out this year ... will be watching this like a stalker.

 

[James Aydelott]

two day events usually have meant better chasing on day1.

The ensemble gfx are frighteningly consistent. should be fascinating to watch evolve.

 

[David Wolfson]

Excellent setup seems to be coming together for west-central Texas. Good CAPE, shear, LI, moisture, timing (18 - 00Z), and rational wind field to move storms from 240 or so at 30kts or less. Some hints of upper left-frontal jet divergence and embedded mid-level vorticity max as well. Overall a nice picture to my eyes that has been pretty consistent for several model cycles.

Target: Odessa, TX

Tuesday night stop in Van Horn to save gas and miles in case it craps out.

 

[cdcollura]

Good day all,

Looking at some of the models and on-going setups, a good chance for a dryline / front triple-point looks to be on tap for Wednesday (4/9). I am already set to arrive in Dallas on Tuesday evening and will be in place (possibly - and tentatively- near the Seymour / Throckmorton) area in W-Central texas on Wednesday.

A surface low is expected to develop in the panhandle / high-plains region in response to another shortwave ejecting out of the Rockies in that time-frame, with attendant dryline setting up south of the system as well.

I will also be targeting points east, possibly into SE Oklahoma on Thursday (4-10) depending on how the previous day turns out.

Good luck to all heading out as these two days do show good promise with good shear (50 knots at 500 MB), backing of winds ahead of low, stationary / warm front + dryline, and CAPE to 3,000.

 

[Jordan Hartley]

Well the models have stayed consistent for this chase day. Im really starting to get excited as everything seems to be coming together. Day 2 SPC convective outlook has a good portion of NC Texas and SW OK in 45% 2 days out which we all know what that means woot woot!!! As always the GFS is a little more aggressive with 65f dews all the way up to the red river valley compared to the nam only showing 60f's. Both models showing a 995mb surface low in SW TX with stong backing winds in the target zone as well as 850mb winds screaming out of the south(Nam showing backed 850mb). Excellent shear at low/mid lvls just gives me goose bumps with all the moisture to play with. Nam has cape values up to 3500 J/kg. And the icing on the cake is the timing of all this which should give us a good 2-4 hours of daylight to mess around with. I might be a rookie at forcasting but this one seems pretty easy for me. This has classic tornado outbreak written all over it. Now just getting off of work without loosing my job seems to be the only problem. Geese if it aint the weather its the job lol.

 

[Rob Lightbown]

In my world of virtual storm chasing, I took a look at the 00Z NAM, GFS and also the latest run of the SREF model. I noticed that the NAM has the best moisture and instability south towards Abilene while the best 0-1 km Helicity values stay to the north over northern and northwestern Oklahoma. Meanwhile, the GFS model forecasts the best CAPE to pull north into southwestern Oklahoma westward into the Texas panhandle. The SREF model's severe thunderstorm probability index shows the best chance for severe is about 60 miles southeast of Wichita Falls, TX between 21 and 00Z Wednesday.

So, based on this, I would probably pick Childress, TX as a good starting point for Wednesday afternoon as this area is in between the best moisture/instability and best helicity values (NAM model). Although, I did notice that something could fire further southwest near or just east of Lubbock as model reflectivity data showed an isolated storm forming very near Lubbock late in the day and it is possible this could be supercellular. So, perhaps something between Childress and Lubbock may be a second option.

Thoughts??

 

[Paul Knightley]

As a continuing effort to get my eye in before May:

Looks like a sagging cold front/outflow boundary from overnight convection should lie from cent OK down to around San Angelo by around 18Z tomorrow, with warm moist air being pumped northwards to its east. By 21Z, ECMWF wants to develop a surface low near Abilene, and by 00Z it's not far from Brownwood, TX, with a nice tongue of moisture extending westwards to the north of the low/south of the front. To that end, I'm going to go for an initial location of Brownwood, TX.

 

[Todd Rasmuson]

one prob i do see is cape values yes they are high but mostly out west around abilene,tx area with capes exceeding 3000+ out in that region, but then when you get in the main body of nc tx including dfw metroplex at 0z tomm showin barely 1000 cape... this is per wrf model run, so this is something to watch we arnt totally locked into this but looks like it will be a bad event if it materializes, that is to be seen -todd

 

[James Aydelott]

Looks like yet another classic day to find that e/w baroclinic zone.

 

[David Wolfson]

Quite an impressive picture -- or more like a flashing strobe -- for west-central Texas even at mid-day, with a sharpening dryline axis around LBB to SJT (as compared to the earlier more backed and diffuse picture). Not much not to like except the possibility that the low levels may be somewhat trashed by early action extending south of I-20. With that in mind I place my bet for early initiation a little further south.

Target [now virtual, due to electronics glitch]: San Angelo, TX

[V 15:30Z] On road taking I-10 east at I-10/20 junction.
[V 16:45Z] No change in picture. Off on US67 toward SJT. Radar loop is suggesting development of sw TX surface low as modeled responding to upper max. Arrive SJT and data watch ~20:00Z.