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02/29: FCST: Severe weather in Texas Sunday?

Karen Rhoden

OK - I thought I'd start a new thread here seeing as the possibility exists for some severe event on some level on this coming Sunday the 29th of February.

SPC Already has a SLGT Risk painted for portions of Texas out west - see the tope of this forum or click here:-

http://www.spc.noaa.gov/products/

Gut feeelings and expectations for this system suggest a fairly typical very early Springtime setup - strong dynamics and a great little system - but, alas, moisture-starved.

Perhaps when we establish a true springtime connection to the Gulf, I'll start watching more seriously!! We mustn't jump the gun, though - the last front went clear through the Yucatan.

Users - please use this thread for any forecasting discussions regarding Sunday's possible events. Thanks.

_______________________________________
Karen Rhoden

www.stormskies.com

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I second your observation of this being a typical late-winter / early spring system. The dynamics are almost as strong as they get, tremendous wind speeds at all levels, but almost a purely meridional (sp?) flow... The 0z ETA does have low 60 tds just about to the OK/TX border by 0z Mon (Sunday evening), which does help instabilities some. Also, the 700-500-2500mb RH graphics all show indications of little cloud cover south of DFW, at those levels at least. The UVV's are off the charts (literally), but I'm sure there's some convective feedback there (does the ETA ever really suffer convective feedback? Now that I think about it, I thought the way the coordinate system is and how the model works that it isn't nearly as susceptible to convective as much as the GFS is...). I'm thinking a very strongly forced, strongly sheared squall line. Easily could be a decent damaging wind event, with 60+kt 700 and upward winds (from the south or south-southwest mind you). I was excited earlier today, but with that forcing, there's no way to get anything discrete cells out of it. Chance of some 'ahead of the line' stuff, but the instability axis/corridor is quite narrow...

Jeff
 
Dynamics like that this early in the year in west texas generally blow things on out pretty quickly. However, I wouldn't discount that moisture return just yet. Some of the effects of that trough are already being seen in the panhandle with increased wind speeds. Models sometimes have problems with diagnosing enough moisture for strong systems like this late winter.

Remember, it was only days ago I was out in the hail and lighting out here in 45 dews! 8)
 
12Z model run is out now. Looking at ETA, It looks interesting for AUS and east along the dry line. Should be able to meet convective temp. Looks like moisture return flow will be in place too. Key is to be on convection before the squall line develops. Decent CAPE, LI, etc for AUS and CLL just before 0Z monday.
 
Forecast: Sunday 2-29 (as of 12Z ETA Friday)

If I still lived in Texas, I'd chase this if only to see convective storms and test some equipment. That said, I don't totally discount the tornado threat, either within embedded mesos in the fast-moving squall line, or any discrete storms forming out ahead of it.

The forcing is strong, and storm motion is parallel to the orientation of the dryline, so anything isolated will be quickly undercut by the rapid westerlies. The predominant mode will be linear convection, I'm convinced.

The system is a little too cool, too fast, and too piney woods for a long excursion from Indiana. Sigh. Guess I'll wait for the next one.

Amos
 
... If it was not in my backyard I would not drive a long distance for this event either.

But when it's close to home you might as well go see some (any) convection :lol:
 
Ya, I agree with Karen & Jeff, a typical early spring system...all the dynamics and insufficent thermodynamics.

ETA is pretty wild with the LLJ (60+ kts @ 850 Sunday morning) and I wonder if the northward extent of the moisture return may be a bit overdone for Sunday afternoon.

All signs point to linear convection mode almost instantly. A damaging wind threat nonetheless....ah...spring really is just around the corner :D
 
from the 10:00 am forecast discussion (AUS) :A BREEZY AFTERNOON AS SOUTHERLY WINDS INCREASE IN RESPONSE TO THE APPROACHING UPPER TROUGH. SCT-BKN CIRRUS ALSO SPREADING OVER AREA WITH LOW LEVEL MOISTURE RETURNING OVERNIGHT. CURRENT FORECAST ON TRACK AND MAJOR CHANGES PLANNED ON THE MORNING UPDATE.
 
from the 10:00 am forecast discussion (AUS) :A BREEZY AFTERNOON AS SOUTHERLY WINDS INCREASE IN RESPONSE TO THE APPROACHING UPPER TROUGH. SCT-BKN CIRRUS ALSO SPREADING OVER AREA WITH LOW LEVEL MOISTURE RETURNING OVERNIGHT. CURRENT FORECAST ON TRACK AND MAJOR CHANGES PLANNED ON THE MORNING UPDATE.

Am I to assume they meant "No major change planned..."...

Jeff
 
Looks like a fast-moving squall line setup. I guess a couple of supercells could develop out ahead of the line given all the energy crashing in, especially if central TX gets dryslotted Sunday morning and heats up. But they'll be making for the Ozarks at warp speed.

I'm excited by the severe weather potential, of course, but I have no real interest in chasing this setup.
 
I am in agreement with the squall line theory. Been keeping an eye on this too. But since I have to work 9-9 Sunday (a rare Sunday workday) it will probably now become the event of the season and I am stuck at work. Argh.
 
THIS WEEKEND STORMS

Everyone is talking about Sunday but what about tomorrow? Would a trip to the Aspermont Texas area be worth it maybe for some evening lightning pics? If so will we see redevelopement along the dryline Sunday afternoon over North Central Texas? I could see following this system a couple days actually.

Jay
 
Oh I AM keeping a good eye on tomorrow, althought right now you might want to come back west from Aspermont and get on the caprock. Oh and bring your flashlight cuz it's looking like a night showing. :)
 
It seems most are going with Sunday being a "squall line" event. Yes, the voriticy advection will be intense, so the forcing and storm motion would indicate a high likelyhood of a squall line where the most intense vorticity advetion is occuring. However, I do think that supercells are likely south of the intense vorticity advection. The shear is going to be amazing, and the 0-1km will be pretty impressive as well. I'm thinking the Waco visinity or south will be a good place on Sunday, based on the ETA. And, if the actual 850mb winds back more than the ETA forecast, the storm motion will be more E than N, hence more perpendicular storm motion to the forcing mechanism.

And for those who are not very optimistic about the current CAPE forecast, which looks to be anywhere from 1000-maybe 1500, take a look at November 10, 2002. Ohio had 500-1000 CAPE, and experienced significant tornadoes. Anyways, the models are not very good at forecasting CAPE, as anyone that knows how CAPE is durived should know.

So, I believe low-topped supercells will occur in the Vicinity of Waco Texas, or central/southern central Texas, with a few tornadoes. Can't wait 'till Sunday!

Happy Chasing,

Jim Bishop
http://stormgasm.com
 
Despite the veering and weakening of the 850 winds south of I-20 this helps out the storm-relative shear. The weakening of the 850 winds also slows down the storm motion and increases the supercell potential. As long as overnight convection doesn't screw this one up and the atmosphere looks similiar to tonights ETA run then I say supercells definitely south of WACO, TX!!! And Jim is correct about the CAPE, the CAPE and moisture will be fine on Sunday south of I-20.

There will be tornadoes reported on Sunday!!!

DO THE MATH!!!! Sunday + Supercells + Feb 29th (leap year) = tornadoes

This will be known as the "Leap Year Outbreak"!!!!!!! (lol)

(Don't take the very last part too seriously!)
 
Well - it's Saturday morning - and would you believe that the SPC's outlooks & forecast discussions page is DOWN?

Try clicking on the Outlooks thread at the top of this Target Area forum. Blank.

They never cease to amaze me......how apt.

K.

(EDITED 8.35am to say it's back it up and running now...)
 
kind of dissappointing from the day 2 outlook:

LIMITING PARAMETER PRECLUDING THE FORECASTING OF A SIGNIFICANT
SEVERE WEATHER DAY GIVEN THE STRENGTH OF THE DYNAMICS IS THE
EXPECTED LACK OF INSTABILITY.
 
After glancing at the 12Z UA soundings, Del Rio's looks the best to me. Their dp is already in the mid-50s. Looks like they will manage some sunshine this afternoon as well. Too bad the major vertical motion/overall energy with this system won't be realized until very late this evening/tonight or tomorrow.
 
After looking at the models for quite some time, I think I'm going to join the group of those who are likely going to sit out this event... Not only is this synoptic setup not very favorable for tornadic activity, but I'm getting myself excited for a possible event Wednesday. This time, it appears that there will be an abundant amount of low-level moisture (mid 60 tds pushing into Red River Valley by 0z thurs / weds. evening) and decent wind shear aloft. I myself am holdin off a couple more days to start up a new topic/thread as models can be quite erroneous at this far out...

Jeff
 
Karen, yesterday I've posted a message about forecast of this week end but where is now?It is disappeared...Let me know please
 
Moderate Risk for Texas!

I don't care what the SPC says. They are forecasting the obvious: short-lived, moisture starved, hail and wind-producing, vorticity-advection, low-topped supercells in Kansas. That will most likely occur, but south of Dallas, TX around Waco there will be a good probability of isolated supercells with good tornado probabilities!

I am issuing my own MODERATE RISK for area South of I-20 and East and West of I-35 from Big Bend Region to the western sections of Louisiana.

3a501376bf7604ffea0a608583d9ef3c.jpg

Simon
 
Re: Moderate Risk for Texas!

I don't care what the SPC says. They are forecasting the obvious: short-lived, moisture starved, hail and wind-producing, vorticity-advection, low-topped supercells in Kansas. That will most likely occur, but south of Dallas, TX around Waco there will be a good probability of isolated supercells with good tornado probabilities!

I am issuing my own MODERATE RISK for area South of I-20 and East and West of I-35 from Big Bend Region to the western sections of Louisiana.


Simon

I don't know as if I'd say "good" tornado probabilities... I'll say I think there's a better chance of tornadic activity south of DFW, but still, directional shear isn't the best (and the best directional shear -- as measured as helicity -- in areas with CAPE >500j/kg shifts towards the TX/LA border and into AR/LA by mid-late afternoon), neither is the fact that the ETA is only forecasting 500-1000 j/kg CAPE over the area. I'm not very impressed... As far as chaseability is concerned, I'd hold on to that hat and hope the storms parallel a major highway, as 70-80kt 500mb winds will definately translate to fast-moving storms...

Jeff
 
Bottom line: I hope this upper pattern will persist or return in about 3-4 weeks!

Dynamics are there, but the tank is just half full.

I have the last week of March off. I hope something will happen then. April is out because of daily tours of schools to TALK about severe weather (dammit), and May sweeps.

Price I am paying to go from news to weather.

later

mp
 
I'm definitely a risk-taking type of chaser, but logic tells me to stay home on this one. Fast storm speeds, target shift into a horrible area for viewing as the day progresses, and tornadoes (if any) buried in squall lines. On their own, any of these three factors of difficulty are doable.....but all three together, I think I'll just sit at home eating junkfood and watching this one unfold from behind this computer.

I'm raring to go, to get my 2004 season underway, but it looks like next week will be the green flag for me.
 
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