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

..

[Jeff Snyder]

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

[David Drummond]

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)

[David Douglas]

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.

[Amos Magliocco]

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

[David Douglas]

... 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:

[Chad Ringley]

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

[David Douglas]

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.

[Jeff Snyder]

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

[David Douglas]

I assume that also...

[Jeff Lawson]

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.

[Carrie Halliday]

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.

[shadowchaser7]

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

[David Drummond]

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. :)

[Jim Bishop]

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

[Simon Brewer]

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!)

[Karen Rhoden]

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...)

[Dan Cook]

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.

[Austin Ivey]

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.

[Jeff Snyder]

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

[petrucci]

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

[Simon Brewer]

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.

http://stormgasm.com/convective%20outlooks/2.28.04.day2.jpg

Simon

[Jeff Snyder]

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

[Morgan Palmer]

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

[Shane Adams]

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.

[Carrie Halliday]

I just have a feeling that the Waco area is going to see something bad. Not sure why, but a gut feeling.

[Tim Marshall]

TARGET: NONE Today is a good day to stay at home and catch up on chores. The dynamics will blow by quickly as the upper system lifts out to the northeast. Surface moisture will be a big problem along with lots of low clouds that will be slow to break in the warm sector. Perhaps mid-week will be the first chase as another system in the series enters the plains. Surface moisture and temps appear better for the next system. TIM M.

[KMcCallister]

I'm not chasing today. My "target city" is Jacksonville, TX , but it's buried 100s of miles into the trees of east Texas. Way too much effort for moisture starved event when I have to be in class at 830am tomorrow.

Kenneth

[Kevin Scharfenberg]

Agreed...in Texas, the combination of cool surface temperatures and warm air aloft, along with all the clouds and trees in the risk area, suggest this isn't worth any effort. The 12Z CRP sounding tells the tale. Good calls by SPC in their two outlooks issued yesterday. Maybe next time.

[Simon Brewer]

It's easy to make a forecast, or should I say NOWCAST at 8am, but when you have to be there early, then you have to make a forecast the day before, and the models did not project the shortwave progressing as quickly.

By the way: over the past 3 days, every outlook reguarding Sunday was changed by the SPC, so they didn't make the correct call days in advance.

[Simon Brewer]

It's easy to make a forecast, or should I say NOWCAST at 8am, but when you have to be there early, then you have to make a forecast the day before, and the models did not project the shortwave progressing as quickly.

By the way: over the past 3 days, every outlook reguarding Sunday was changed by the SPC, so they didn't make the correct call days in advance.

[Shane Adams]

Originally posted by Simon Brewer
It's easy to make a forecast, or should I say NOWCAST at 8am, but when you have to be there early, then you have to make a forecast the day before, and the models did not project the shortwave progressing as quickly.

By the way: over the past 3 days, every outlook reguarding Sunday was changed by the SPC, so they didn't make the correct call days in advance.

I dunno, I was never really excited about Sunday once the models started picking up close-to-reality runs. Of course it was easy to wake up this morning and say "crap, I'm staying home," but was I surprised? No.

You went out on a limb and got burned with your forecast, so it's understandable why you'd be little more miffed than the rest of us - I've been there. At least you stayed home; 2 years ago I actually gambled on my longshot February chase forecast and found myself in east TX under fair skies staring a 6-hour drive home right in the face.

[Jeff Snyder]

Simon,

It's always tough forecasting this time of year, when dynamics are so strong, and we await possible last-minute moisture. I think it's not a very good move to evaluate anyone's forecast, be it SPC, TWC, or someone on this board, unless you're doing it for official verificatin (SPC does a lot of verification work, btw). Of course, I'm not saying verification isn't important, as I think verification is VERY important in improving forecasts, but if it's not done following a good procedure and done persistantly, then it becomes an informal process and more likely to be a forecast-bashing situation. We all get burned from time to time, which is all part of the learning process...

Consecutive runs of the ETA were forecasting more and more ll moisture in the area by today; in other words, dprog/dt showed the ETA was forecasting, increasingly, the return of decent moisture to eastern TX and OK. In the end, much of eastern OK/TX was overly forecast (sfc td-wise). Lon Curtis mentioned it in another list, but there have been and still are numerous and persistant problems with the Mexico RAOB stations not getting their data collected soon enough to be ingested into the NCEP models. This becomes a signficant problem when these systems affect northern Mexico, and that data-void becomes very important.

Jeff Snyder
KC0HJX
http://www.TornadoCentral.com

[Simon Brewer]

By no means am I discrediting the SPC, but people should know that almost no one makes a perfect forecast days ahead of time, that is why it is called a forecast and not a 'profecy', 'destiny', or 'fact-before it happens'. Got burned today and will have more successes and busts in the future. I knew the setup, I knew what could go wrong (for the past 3 days I was worried the shortwave would eject a little quicker morning convection would screw things up), but you have to take your risk or you will never go chasing, because storms don't initiate over your house everyday and tornadoes don't touch down on your lap often, unless you've lived in northern Moore the past few years, then I consider you unlucky.

But yes, I took the risk and was burned, and in a few days I will make a forecast for Wednesday.

Happy Chasing to all, Tuesday and Wednesday look to be eventfull!!!

[Simon Brewer]

Too late Shane, I left last night around 1am and was east of Austin staring at data that I didn't want to see at 7am.
I was burned, but saw a week gust front, light rain, and partly cloudy skies all the way home.

Just waiting for Wednesday, because I'll do it all again. Got to keep the gas demand high!

[Bob Schafer]

If you read this soon enough (It's 9:28PM CST as I type this), and want to see some impressive imagery of tonight's storm, go to

http://weather.cod.edu/analysis/satrad.regional.html

Then, choose North Central US, and run the IR w/MB-curve loop.

Very cool.

Ummm...I have no way to save this and post a link for others to see this later. Maybe someone else could??

Bob

[Bob Schafer]

Here's another "image" I saved from tonight:

http://community.webshots.com/photo/345395...122150035JPUPRj (http://community.webshots.com/photo/34539595/122150035JPUPRj)

Bob