05/05/09 FCST: OK/TX

[Niccolò Ubalducci]

Target for May 5: Sweetwater

 

[Dan Dawson]

Most recent runs look like the show shifted west and south a little more? LOL. Well Cap is now stronger for the most part and the NAM now has it with no precip not even along the warm front really. LCLs are a little bit weird but I dont think they are bad enough to warrent not chasing. But the Cap is for sure! EHIs have increased right where the cap is strongest, LOL. Its just ugly. Things could change again, just too far away for me.

Mike has a point, to much turning in the upper levels. Even more so than 4/7/08. So seeding(so to speak) is a question. Be interesting to see what happens.

I do think though that if anything where to get going, being on it early would be the key. Good photo ops could be abroad!

Hmmm... actually the cap looks weaker now on the 0Z run of the NAM. The CIN is pretty much gone by 0Z for a large area around ABI. However, the dryline bulge appears less prominent and further west. The 0Z NAM actually has more precip along I-20 and south, between 0 and 6Z, which is significantly different from the 12Z run, which was breaking out much less precip. Nevertheless, CINH is still prohibitively strong north of the dryline bulge, and CAPE drops off rapidly as well. We are going to have to hope for initiation east of the dryline bulge that is able to sustain itself in the face of increasing CINH after dark. FWIW, the 4 km EMC WRF does have a storm cluster forming quite a bit further east of ABI than I would have guessed, around 0Z. We will see.

Dan

 

[Ilya Neyman]

It's a tough call whether the current severe probs maybe a tad further north and east of where things may be most favorable. Still too much uncertainty regarding much more of a delineation as morning-midday convection has yet to enter the picture. A secondary area of interest may develop over the high plains of the TX panhandle, roughly in a corridor across the western TX/OK panhandles and west KS tomorrow afternoon as easterly upslope flow moves moisture west underneath strong W/NW flow aloft. 4 km hints at a few cells popping in this environment as well. While moisture will be richer further south and east, the combination of ingredients may be something to watch for perhaps an LP storm out there. Just a thought for anyone in those parts already.

 

[Brandon Lawson]

The cap has been all but a joke this year, failing to hold off convection late into the day on a good number of chases. A lot of it probably has more to do with the timing of forcing, rather than CINH strength, but still, it's aggravating nonetheless. I recall March 26th coming close to being the first true cap bust before producing a couple of good storms before dark. It would be a nice change to see some instability build beyond the 2-3pm time frame.

I'll be out tomorrow. Forecast hodos are nice around the red river. I'm hoping for morning convection to clear off earlier than the 4km WRF shows. Will target St. Jo possibly, and readjust accordingly.

 

[Jake Wallentine]

Kevin and I will probably be playing the warm front tomorrow along the red river. We like the area just south of SPS. The LCLs look quite a bit lower there than along the dryline...and hodos look just as pretty...just hoping we can get enough convergence(maybe an OFB?) to get things going.

 

[Jim Tang]

Morning convection is a huge development. I suspect it will preclude the northward progression of the warm front. This, coupled with the strong EML advecting in from the SW, makes me dubious of deep convective initiation. However, given initiation, I guess we could see a storm ride warm front or boundaries left over from the morning MCS. Who knows, it might also help LCL-wise. Lots of options of the table. I would think the cap is underdone, and that the warm front is too far north on model progs. A good prelim target would be NW of Denton, TX.

 

[Darrin Rasberry]

Morning convection is a huge development. I suspect it will preclude the northward progression of the warm front. This, coupled with the strong EML advecting in from the SW, makes me dubious of deep convective initiation. However, given initiation, I guess we could see a storm ride warm front or boundaries left over from the morning MCS. Who knows, it might also help LCL-wise. Lots of options of the table. I would think the cap is underdone, and that the warm front is too far north on model progs. A good prelim target would be NW of Denton, TX.

I second your forecast, taking a look at the 18z prog from the 06z RUC. It shows the front as even more sharply defined than the NAM progged it, and even breaks out some precip both north and south of this front along the area highlighted by the SPC this morning. If so, areas that get drenched too far north may not have time to recover if the boundary continues to lift, but there are plenty of examples to the contrary, and besides, I'm with you that the cap may be underdone. Nonetheless, I would choose your target of Denton, as well, maybe Graham - looking for development between 4-6 PM.

 

[Ryan Pfannkuch]

Starting the day in dreary Norman with Ben McMillan and Quintin Erdman. Not sure what to make of this setup, as elevated convection is just now starting to ramp up across SW OK and south to the Red River, but at least initially the coverage does not extend as far S/SW as short term guidance suggests it will. Basing my initial thoughts for the day off the 12z RUC, the surface boundary appears it will struggle lifting as far north as it appeared 24 hours ago, and low-level RH progs suggest the current stratus over TX could be quite slow to erode. At first glance, I'm gonna adjust my original 4-county target area one row south from my post yesterday and go with: Throckmorton, Shackelford, Young, Stephens (including Albany, Breckenridge, Graham).

0z forecast sounding for Graham looks pretty interesting, even if CAPE is overdone, with favorable LCL heights and 22kt 0-1km shear. Gonna be very interesting to watch the evolution of ongoing elevated convection and potential stubbornness of stratus south of the Red River.

 

[Darrin Rasberry]

Great deal of crappo still hanging over my hometown of Wichita Falls and the rest of the MDT vicinity at the moment; the RUC is still advancing the front to the Red River area by 6ish, but I don't know as if that cloud cover will allow the drifting to be that significant. I will still stand by my call of Graham. Wish I were there, especially since I know the area well, but duty calls ...

 

[Darrin Rasberry]

Of additional note: there's a nice little bulge forecast by the RUC just south of Abilene at 00z as per the 15z run.

 

[Bill Schintler]

Chase Target for Tuesday, May 5

Chase target:
15 miles north of Graham, TX (or 80 miles northeast of Abilene).

Timing and storm mode:
Supercell storms will develop after 5 PM CDT. A full spectrum of severe weather is likely, including a tornado or two.

Discussion:
An elevated convective complex continues to track E along and N of the Red River. This should result in an OFB which should push S to about I-30 in NERN TX while merging with the synoptic E/W-oriented boundary. Large hodograph curvatures are likely along and N of these boundaries as a 30kt SSWRLY LLJ overspreads strongly backed SFC flow. The SRN periphery of an extensive CI deck will slowly push NWD during the afternoon, allowing for strong insulation as far N as the Red River.

Timing of SFC-based convection is a challenge. Subsidence will be the rule for the next several hours with the area in the wake of a lead shortwave. Later in the afternoon, assent again increases as an H7-H5 shortwave arrives in WRN TX with attendant mid-level cooling. Parameters suggest supercell storms and tornadoes. Strong instability will develop as mid-level lapse rates increase to 8C/km and dewpoints increase to 70F. Deep layer shear of 50-60 kts will assist in storm organization. Large hodograph curvatures and LCL’s in the 800m AGL range will increase the likelihood for tornadogenesis within supercell storms.

- Bill
12:15 PM CDT, 05/05/09

 

[Larry J. Kosch]

Possible WW in TX, OK

SPC is having a mesoscale discussion about the weather conditions in TX and OK.

http://www.spc.noaa.gov/products/md/md0708.html

What's disappointing is they only expect large hail and damaging winds. Where's the tornadoes??

EDIT: SPC has posted SWW 425 for SE OK and NE TX. And they listed the probability of tornadoes as LOW!!

EDIT: SPC has a mesoscale discussion about TX http://www.spc.noaa.gov/products/md/md0710.html
Let's hope for a supercell development!!

 

[Bret Hendrickson]

Looks as though the MD is referring to the ongoing convection in southern OK. I'm certain another MD will detail the expected surface-based convection in TX later this afternoon (along with the possibility of tornadoes).

 

[Brian Stertz]

Looks like the warm front is setting up to be main show at least initially....looks like things may seriously cap off south of I-20. This would put all the great juicy LL inflow into the supercells which should initiate within the next 3 hours between Abilene and Ft. Worth and north of I-20...Graham-Mineral Wells is the target bulls-eye I will go with... although initiation may be a bit west of there. I am helping Jeff with some nowcasting and he will be closing in on the target within the hour. Things look pretty serious for a very active afternoon & evening for N. Texas. Tornadoes look to be a good bet, especially for the supercells closer in towards FTW and away from the 10-12 degree 700mb cap.

 

[Derek Weston]

with the warm front apparently not making it as far north, this becomes a more compact, more favorable setup, potentially. . . the best instability and SRH more closely placed. Already we've got a sizeable pocket of SBCAPE at 3500 J/kg. . . and a good amount of SRH helicity near the front. Very good turning with height as well. (with solid upper level support)

Should the cap break in a timely fashion... later in the evening when the low level jet starts to kick in, in the vicinity of the boundry/WF... we could have a rather volatile situation. (IMHO)