4/17/07 FCST: TX / OK

[Billy Griffin]

Not much to this system as it appears for now, (dewpoints no greater than ~40 all the way to the gulf - ouch!) but still wouldn't be surprised to see some hailers with such cold air aloft. Looks like the primary threat will be south of the Red River once again, in Texas, where they really don't need any more weather problems. Nevertheless, might make for a good local chase if you reside in northern / central Texas. Maybe some lightning photography ops?

 

[Bill Tabor]

Hmm...I don't get it. Is everyone looking at an old run? Nothing on SPC for this day, but today's 0z Nam/Wrf showing 55 to 65 dewpoints in Tx with inbound midlevel vorticity intersecting sfc low, obvious dryline bulge, etc, etc. Am I on the same planet, or just reading some bizarro version of the model?

Guess I should go into a bit more detail. Looks like possible severe, supercells maybe a torn in north central to north east Tx. With apparent rapid moisture return and approach of midlevel disturbance appears sfc cyclogenesis is possible in north central Tx. Dryline should develop and begin punching east from 18z in this same corridor. Additionally though there is some veering at 850 a bit west - generally east of I35 sfc to 850 is southerly or slightly backed. Some inbound jets of 700mb intersecting. By 0z PVA from mid level has crossed most of Tx with widespread convective breakout. Additionally 300mb jet and above shows divergence above this area. By 0z Li's to -4 cape up to 1000, helicity 100 to 400. Rock on!

I suppose the big question is whether or not with 40's dewpoints in Tx this is real and the Gulf can really open back up. Guess we will likely see sometime tomorrow, but apparently NAM thinks it can.

 

[Amos Magliocco]

I can see the potential for cold-core style mini supercells along the arcing warm front in north central Texas between 18z and 20z. Very cold temps aloft along with strong CVA and impressive 3k CAPE values seem to indicate some potential if the forecasted dry slot verifies and allows insolation over the area forecast to reach lower 50F Tds.

These sort of setups seem to come and go on the models with ease so I won't be surprised if the 12z shows these ingredients more or less out of phase.

 

[Shane Adams]

Might not be attractive for many chasers, but since I'm probably the only active chaser I know who's still at 0 in 2007, Tuesday looks like an interesting possibility for the needle-in-the-haystack. If those dewpoints verify, could be interesting (and probably difficult). That advertised DL bulge looks absolutelty delicious, the type of ingredient that ignores lack of high CAPE and temps. We'll see....but as I'll be in DFW all week for work anyway, basically another backyard event for me (ala April 3). Now that I find myself down here more than OUN these days, I'm diggin' all these TX events.

 

[Kenny Drake]

The main problem with this system is the stacked nature of the low. Cloud-cover and ongoing precip in the warm sector on Tuesday will likely inhibit any sort of destabalization because inhibition will already be removed due to the 500mb closed low being overhead. However, with the crazy dryline bulge being forecasted by the 00Z NAM i'd still expect a fat MCS out of this stretching from DFW southwards with the possibility of some embedded supes. NAM forecast sounding for KDFW @ 7pm CDT looks okay:
http://beta.wxcaster.com/cgi-bin/parse_skewt_trace.cgi?model=NAM&fcsthr=048&STATIONID=_KDFW
The major problem I see with this scenario are the winds being relatively weak and unidirectional from 800 to 500mb due to the proximity of the closed 500mb low.

 

[Billy Griffin]

As of 5am CDT, TDs in the mid to upper 40s right along the coast. I suppose surface moisture recovery "could" happen, but it will likely be very shallow, very shallow. But good luck to those who are able to chase tomorrow. Sometimes, these last-minute chases turn out to be a good day, and maybe of even more benefit, there won't be 2,000 people lining up along every little highway and back road in north Texas.

 

[Billy Griffin]

Very narrow plume of ~ 50+ TDs forecast ahead of rapidly developing surface low progged for the Red River Valley of Texas. Definitely looks like high-based convection, but ya' just never know. It's now that time of year where just about anything goes!

 

[Jim Bishop]

This looks really interesting. A very strong/tight vort max moving right through Central Texas. 500mb temps -16C to -20C. Alll you need are dewpoints in the mid to upper 50s, and we should get low 60s by early in the evening to support ~1000 j/kg CAPE.

As long as the 850mb winds remain backed (near southerly instead of southwesterly), low topped supercells should develop (as apposed to multicell storms) along the dryline/trough axis ahead of the surface low from Dallas southward to I-10 inbetween the I-35 to I-45 corridor.

With the 30-35 knot southerly 850mb jet and a fast storm motion, I smell some tornadoes in East Texas tomorrow. I may have to leave work an hour early and just GUN IT north on I-45....

 

[Bill Tabor]

Still may be a possibility, and I see now that SPC had outlooked the area, but I don't think I am as bullish given this morning's 12z run compared to last nights 0z. I don't see the sfc and upper coordinating quite as much. The low isn't quite as deep as I care for, and I see that even though pressure is down in Tx, the actual circulation seems to be seen further north in OK where dewpoints shouldn't be as good. Surface and 850 don't currently back as much as I'd like and when they do they are closer over toward LA and somewhat out of the instability axis further west. EHI's aren't too great until 0Z and then they show in a small area near Stephenville / Corsicanna a bit over 2 I believe. I still see some good 500 mb vorticity inbound to the area though and the 300mb jet divergent flow over the area will help too although may break out widespread convection. Seems at least there is some cinh early on to hold a bit until the mid level UVV can lift and break.

I see lower 50's dewpoints this morning along the Tx Gulf so if the advection conveyor gets going tomorrow afternoon near DFW general area is not so hard to belief.

Will have to keep watching and analyze this some more. It is not a strong wide spread severe threat, but often some of these lazy Slights turn out to be good chase days. It only takes one good tornado to make me happy, but I am a bit skeptical / reserved on it at the moment.

It bears watching to see how it develops and what the next model runs will bring.

 

[Ray Walker]

I dont know guys, Models are showing a rapid moisture surge into north texas and Oklahoma late tomarrow morning into the afternoon. I think that we could see at leas a couple isolated supercells across southern Oklahoma and northern Texas. Hail up to golfball size and a few breif tornadoes appear very possible to me. Dewpoints close to 60, and very cold temps aloft should be adequate for some interesting storms especially if some surface heating occurs. Not a big event by any means but pretty interesting if you are in close proximity to the red river.

 

[Shane Adams]

Still quite a longshot, but if dewpoints and that subtle little surface low west of DFW verify, could be interesting. Directional shear is crap but there seems to be a bit of speed shear, and if that low develops as advertised, that should provide nice turning in the lower 1 km. If things stay generally the same through tonight's runs, my target will be Grandview, TX. It's only a 30 mile drive from where I'm at so why not have some fun in the hay and maybe find a needle???

 

[Billy Griffin]

Current data for the DFW metro:

Hillsboro Municipal Airport
Lat: 32.08 N Lon: 97.1 W Elev: 686 ft
Last Update on Apr 16, 8:08 pm CDT

Fair

64°F
(18°C) Humidity: 64 %
Wind Speed: S 7 MPH
Barometer: 30.04"
Dewpoint: 52°F (11°C)


TDs already in the 50s! Winds S/SE over most of SE Texas. Looks like that moisture return will make it after all. I hope that stuff in New Mexico doesn't continue on as a nocturnal event, thus limiting our daytime heat tomorrow.

Otherwise, this just might wind up being a little surprise event in a narrow area along or just south of the Red River.

Good luck to all chasing tomorrow!

 

[Shane Adams]

Judging by the latest RUC I'm not too optimistic now because the best instability is misplaced from the best shear/helicity.....so the goal today is to try and find that magical spot in between and hope something happens. Looks like the area of interest will start around 18Z in NW Texas and gradually transition ESE throughout the day, west of the FTW area. I'll probably head west on I-20 and then work my way NWrd towards the area south of SJS. Currently at work in Irving waiting on the next SPC outlook, to see if they agree with my current assessment. Either way, I'll probably roll the dice and head out around noon.

 

[Bill Tabor]

Appears latest NAM run is once again less favorable for good severe, supercells, tornadoes. In the region of western and central north central Tx, I see fairly weak somewhat diffuse sfc low, somewhat displaced too far west and north, and not backing winds at sfc and 850 as is needed. Likely as a result the dewpoints are not as strong further to the northwest nearer the low and possibly mixed out somewhat. Sfc winds are weak, 850's are somewhat veered. Cape seems meager at 200 to 750 except perhaps in areas of steeper lapse rates. Instability and shear seem to be displaced from each other from 18z to 0z leading to low EHI levels. Upper jet streak, and mid level low lift will likely break out more storms over a widespread area and further stabilize. Etc. Looks like I pretty well agree with Thompsons assessment of low chance of classic supercells & tornadoes in Tx today. As for landspouts and cold core low topped storms - I will defer to others opinion, but seems that doesn't appear that strong either.

At the moment, unless SPC Mesoanalysis product goes bonkers, and we somehow get incredible unforeseen insolation with correspondent strengthening of low, backed winds, increased instability, etc I will likely stay home.