10/8/09-FCST: TX/OK/AR/IL/MO/IN

[Brendon Lindsey]

Looks like there will be considerable forcing with this system sweeping through plains tomorrow. There will be a great amount of shear accompanying it, with DP into the 70's. The question really is are we going to be able to keep the clear skies in order for use to reach at least 1000+ Cape. The system very well has the chance of producing a few tornadoes. SPC mentions large curved hodos. I don't know for which station, but they are kinda hyping the situation. Suprised a thread hasn't been started... Also look-out NE OK NW AR for significant flooding.

 

[Jeff House]

This day looks to have slightly less chances of becoming a lined out train wreck than the last two or three, so I will not ignore this one. Of course the risk of a rainout is there. It is less capped and moisture is very thick, both of which can be your best friend or worst enemy depending on the mesoscale details. On the plus side we actually have true southern stream energy ejecting into the warm and very humid surface environment. Still slightly positively tilted, and I strongly prefer negative tilt, but will take what I can get in the already El Nino induced split flow.

A negatively tilted wave would have a better chance of a robust warm front surging, along with a clearing warm sector. Fortunately, even with this positive tilt, the lack of a surface high jamming in dry air from the north will help a lot in allowing the warm front to lift. Boundary never made it past I-10 and Houston is "enjoying" 78-80 dewpoints, which is another plus for a march back to at least the Red River by game time. Could get into central OK. Should get weak cyclogenesis from southwest Oklahoma to northwest Texas by midday.

Need the following. Boundary cannot get hung up at the Great Wall of I-20. Morning low clouds will be widespread and thick but we should not face a deck of high clouds above. A little breezy to mix out low cloud deck, and even the Oct sun might break through. Convection north of the boundary will start well before dawn. I will look to target isolated cells in the warm sector from North Texas to south-central Oklahoma. If a line forms in early afternoon there is a potential for it to actually break up a bit by late afternoon before once again lining out. Jet energy pushing out could promote the discrete cells. Lot of ifs in this forecast, but believe it is worth packing up before work in case early departure is appropriate. Weather should go relatively early in this fall setup so will plan accordingly departure time and work arrangements.

Good luck and chase safe. Cheers!

 

[Andrew Ryan]

It's amusing to see a thread pop up as soon as the spc hypes the setup. But anywho, I'm definitely interested in this setup. My biggest concern, other than the instabilty issues, is the badly veering 850 winds. It's pretty bad on the GFS, but not as bad on the NAM. Have to see what happens with the models tonight and tomorrow morning.

 

[cdcollura]

Good day all,

I see SW flow at all the low levels for 0z on Friday (thursday aft / evening) ... So tornadoes may be a bit quelled.

Hail and high winds should be the major threat if instability verifies...

 

[Patrick Marsh]

A negatively tilted wave would have a better chance of a robust warm front surging, along with a clearing warm sector.

I strongly disagree with this statement. If this system had a negative tilt, the forcing would be way to strong for the set up. As it is now, the forecast soundings are quite moist. Couple this with the fact there is no EML in place (well, maybe ADN in northeast Mexico...), and nothing upstream to promote the development of one, the strong forcing associated with a negatively tilted short-wave trough would result in widespread precipitation - even across the warm sector. If there is a deep, moist profile, a little heating goes a long way in terms of buoyancy production...coupled with strong forcing would result in clouds and precipitation everywhere.

Ultimately, I agree that the warm sector will need to clear...but that looks to be tough. Moist profiles without the presence of an EML across the warm sector will result in buoyancy and cloud development anywhere that receives daytime heating. With that said, low-level shear looks to be very strong across the warm sector(SREF mean 850mb winds look to be around AOA 40mph throughout the day across SE OK, while the NAM has ~50mph)...even though it appears to be more unidirectional than most would like. It won't take much low-level buoyancy to realize this kind of shear. (The faster the wind speeds, the less deviant motion required to increase helicity.)

 

[Brandon Sullivan]

SPC mentions large curved hodos. I don't know for which station, but they are kinda hyping the situation.

As mentioned in the 08.06z Outlook the best hodographs are going to be found across Southern MO and even more into Southern IL and IN. This area is influenced by an H85 Jet Streak, and also backing surface winds.. The FCST hodographs are indeed curved substantially, but I would hesitate to call them "long" due to the meager surface winds.

08.00z 4KM WRF not trying to show much discrete activity in the above area, but I still think tornadoes are a threat, and think that the 5% outlined by SPC is warranted.

 

[Andrea Griffa]

As mentioned in the 08.06z Outlook the best hodographs are going to be found across Southern MO and even more into Southern IL and IN. This area is influenced by an H85 Jet Streak, and also backing surface winds.. The FCST hodographs are indeed curved substantially, but I would hesitate to call them "long" due to the meager surface winds.

08.00z 4KM WRF not trying to show much discrete activity in the above area, but I still think tornadoes are a threat, and think that the 5% outlined by SPC is warranted.

I agree with you, even if I wouldn't rule out too much the dry line east of the Childress/Paducah area along the bulge, where we have nice veering in the low levels, dews and strong speed shear.

 

[Tim Marshall]

Agree with Andrea. I am looking at the N TX option. 10AM update: Looking at a target around Graham, TX -just NW and W of the DFW metroplex. PROS - Deep surface moisture in place, strong upper trough approaching, strong LLJ forecast by 00z. CONS- Low clouds, poor visibility, fast moving storms. I expect a squall line to quickly form along the cold front so I am more interested farther south where there is a zone of backed surface winds somewhere west of Graham, TX.

 

[JustinRudicel]

If we can get rid of this weak elevated crap, I like the dryline as well Andrea. Plus it doesn't hurt that I live and work here in Lawton. Too bad the surface low has weakened so much but still a nice moist southerly fetch . Should be interesting to see how it plays out this afternoon. I would just go to Montague county in North Texas. As there has already been 3 tornadoes(seperate storms) in that County this year. The rest of my viewing area 28 counties, zero. Be safe to everyone that chases today.

 

[Jeff House]

Lack of a strong pre-frontal trough so far today for the Texas target. DL appears unlikely with rain showers in West Texas but I am looking for a least a trough ahead of and south of that cold front. TX will need something other than that cold front. If all else fails, watch squall line from living room in Dallas.

If this system had a negative tilt, the forcing would be way to strong for the set up.

Thank you Patrick for pointing out this clarification. Yes a neg tilt would make this an even bigger train wreck than it is looking like. Perhaps I was unconsciously responding to discussion in a separate thread where it seemed they preferred pos tilt. Though generally neg is better for big days with all the difluence and lift, but that assumes an EML and Miller Type I loaded gun sounding. Not quite there today; therefore, glad you pointed it out and I totally agree with you regarding today.

And good luck to you on the warm front from OK to MO. Clouds breaking up along it look good to promote some instability. If you like the morning rain rule it is also in your favor. Good luck and chase safe.

Cheers!

 

[Paul Redmond]

Yet again south central texas seems poor. I agree that a DL is unlikely today given the rain in west texas. The general overcast south of the front does nothing to encourage me. I too forsee a late night heavy, wet, and and noisy batch of linear convection moving off the coast late Friday morning.

Good luck to those up north.

 

[Brendon Lindsey]

Wow check out current MesoAnalysis 4000 CAPE into SC OK and NC TX. ADM with Temp of 86 and DP 77. Sig Torn 5 & 3. I would like to see more lift, but it looks as if there are a few storms trying to break the cap right now and tap into the abundance of instability.

 

[Paul Redmond]

The overcast actually cleared. I am now seeing some nice storms along the dryline, and I had pretty much written today off.

could somebody lend me some ketchup to go with that crow that I am eating while I am stuck at work late tonight.

Best and safe wishes to all who are chasing today, and wait until the next system.