TORNADO DAMAGE SURVEY: COLLIN/GRAYSON COUNTIES TEXAS

[mikegeukes]

PUBLIC INFORMATION STATEMENT
NATIONAL WEATHER SERVICE FORT WORTH TX
350 PM CDT WED MAY 10 2006

...INITIAL RESULTS FROM DAMAGE SURVEY IN COLLIN AND GRAYSON COUNTIES
FROM STORMS ON MAY 9TH 2006...

NATIONAL WEATHER SERVICE METEOROLOGISTS CONTINUE TO SURVEY DAMAGE
FROM TUESDAY EVENING`S TORNADOES ACROSS COLLIN AND GRAYSON COUNTIES.
THE SURVEY TEAM FOUND DAMAGE FROM APPROXIMATELY 2 MILES
EAST-NORTHEAST OF ANNA IN COLLIN COUNTY TO 2 MILES SOUTH OF
WHITEWRIGHT IN SOUTHEAST GRAYSON COUNTY. A SMALL BREAK IN THE
DAMAGE PATH EAST OF ANNA WAS RECENTLY FOUND...SUPPORTING SPOTTER
REPORTS OF TWO SEPARATE TORNADOES. THE WORST DAMAGE TO SINGLE FAMILY
HOMES...JUST NORTH OF WESTMINSTER NEAR AND EAST OF FM 3133...HAS
BEEN RATED UPPER F3 ON THE SCALE.

NATIONAL WEATHER SERVICE METEOROLOGISTS CONTINUE TO SURVEY THE
DAMAGE AND ARE WORKING WITH WIND ENGINEERING EXPERTS TO PRODUCE A
MORE DETAILED DAMAGE ANALYSIS AND SUMMARY.

AN UPDATED PUBLIC INFORMATION STATEMENT WILL BE ISSUED LATER TODAY.

More information from the NWS Fort Worth can be found here:
http://www.srh.noaa.gov/fwd/collintor06.htm[/b]

Will post information later, Mike

 

[Tony Lyza]

It should be noted that the rating is preliminary; however, if it remains F3, I think the main argument (not that I like this one the least bit) is the slow (10-20 MPH) storm motion.

 

[fplowman]

Amazing...another high end F3. I wonder why so many tornadoes this year are clustered right in that 190-200 mph range. Hmmm... :blink:

OK just reviewed damage photos and I have to admit I'm perplexed. There are houses that aren't there. Not a stick of them is even in the shot. No teddy bear, no water heater, no nothing. Nothing!!! Everything was swept away!

If thats an F3, what does an F5 do? Take chunks of land and throw them thousands of miles?

Sorry, just really confused. It seems the top end of the fujita scale is an F3 now...I mean I know it isn't but could someone with damage survey experience please explain.

Thanks.
[/b]

Building practices for the structures hit are taken into consideration when making an assesment Alex. Without going into an hour long explanation of strapping, different nailing ie (toenailing, etc.. ) that is a good explanation to try to answer your question.

Tim Marshall gave an excellent presentation at the 2006 chaser convention on damage assesment. It was very informative.

 

[Tony Lyza]

When there is NOTHING LEFT on or anywhere near a foundation, unless that home is a prefab, a mobile home, or not anchored to the foundation, it should be violent damage.

 

[Sam Sagnella]

I wouldn't be shocked if they bumped this up to a lower F4 for the final rating. There are a couple of what *appear* to be (and therein lies the problem of 'virtual damage surveying' lol) well-built homes that were reduced to foundations with most of the debris removed at least a short distance downstream. Also was very impressed by the level of ground scouring seen on the damage path flyover done by the WFAA team out of Dallas (http://www.wfaa.com/).

 

[mikegeukes]

THE THIRD TORNADO WILL BE RATED F3 ON THE FUJITA SCALE.
USING THE NEW ENHANCED FUJITA SCALE GUIDELINES...MAXIMUM WINDS WERE
LIKELY IN THE 150 TO 160 MPH RANGE.[/b]

MORE INFORMATION:
http://kamala.cod.edu/offs/KFWD/0605110056.nous44.html
http://www.srh.noaa.gov/productview.php?pil=PNSFWD&max=51

 

[Darren Addy]

Did anybody see in the television station video, after the shot of the scoured path in the field, they panned right (E/SE?) about a 1/2 mile and there was a pickup that was pushed off of its driveway out in the field about 80 yards? (You could see the tire marks as it was pushed through the field - sideways). It hadn't been picked up, hadn't rolled. Just slid straight sideways for quite a distance.

Would that possibly (probably?) be caused by RFD winds? It was far enough away from the scouring (and pushed in virtual straight line) to make me think it was not the rotating tornado winds *proper* that caused that.

Any thoughts?

Darren Addy
Kearney, NE

 

[mikegeukes]

TV Station Links:
http://www.wfaa.com/
http://cbs11tv.com/
http://www.kdfw.com/
http://www.kten.com/
http://www.nbc5i.com/index.html

Newspaper Links:
http://www.dallasnews.com/
http://www.dfw.com/mld/dfw/
http://www.dentonrc.com/sharedcontent/dws/...r.183a2e9e.html
http://www.herald-democrat.com/articles/20...news/news01.txt
http://www.planostar.com/articles/2006/05/...news/news02.txt

Mike

 

[Andrea Griffa]

When there is NOTHING LEFT on or anywhere near a foundation, unless that home is a prefab, a mobile home, or not anchored to the foundation, it should be violent damage.
[/b]

Yes, I think you're right. In the aerial video you can see F2 damage with some houses, F3 damages, but in some cases you could see also F4 damage with at least 3 or 4 well constructed houses filmed by the cameraman that seem to be leveled.
I think that low end F4 could be a better classification. Anyway I didn't go in the path of the tornado to take a look with my eyes so I gave only an opinion.

 

[David Brookshier]

Yes, I think you're right. In the aerial video you can see F2 damage with some houses, F3 damages, but in some cases you could see also F4 damage with at least 3 or 4 well constructed houses filmed by the cameraman that seem to be leveled.
I think that low end F4 could be a better classification. Anyway I didn't go in the path of the tornado to take a look with my eyes so I gave only an opinion.
[/b]

I didn't get to do much in the way of chasing this storm Tuesday night since I had to go to work but I did capture some amazing shots of the meso looking north toward Mckinney. This storm developed rapidly as the cap broke and organized very quickly. The devesation caused to homes by this tornado was tragic F3 with possible F4 damage... in Collin county that's unheard of.

 

[Greg Stumpf]

Before folks start spouting the anti-F4/F5 conspiracy theories again with regard to this tornado event, consider that the damage survey team included two members of the national Quick Response Team (QRT) that have extensive tornado and wind engineering experience (namely Gary Woodall and Tim Marshall).

 

[Gabe Garfield]

Impressive tornado damage, yes, but do we need to always draw the conclusion that it was a violent tornado simply because a foundation was wiped clean? All that have posted here were around for the last discussion (the TN high-end F3), and we now know that the houses that were wiped clean were poorly constructed (lawsuits are pending regarding shoddy construction).

In the past, this tornado probably would have been rated F4 (based on Fujita's rough categorization). Yet, we now know that it doesn't take 200 mph winds to do the damage that was done on Tuesday night. So, in the name of good science, we must not jump to conclusions every time we see a leveled house. I'm quite certain the people who conducted the damage survey of these tornadoes are far more experienced than most of us combined.

Gabe

 

[Brian Stertz]

Excellent points Greg and Gabe. The tornado damage surveys can tell a lot more than generalized damage path pics and fly-overs by media can present. You have the most expert damage survey people around in that area and that rating was probably scrutinized more than most surveys are. Whether it's an F3 or F4, it was still very bad damage and certainly had a terrible impact on the community of Westminster and the surrounding area.

 

[rdale]

Speaking of disappearing F4/F5's -- check Dr Doswell's latest http://webserv.chatsystems.com/~doswell/EFscale_rant.html

 

[Justin Turcotte]

Speaking of disappearing F4/F5's -- check Dr Doswell's latest http://webserv.chatsystems.com/~doswell/EFscale_rant.html
[/b]

F4's are endangered, F5's are extinct. I don't always agree with Doswell but I think he really hit the nail on the head with his latest rant. Someone in the Gallatin, TN thread mentioned the some government conspiracy theory and Doswell may have found it... Too damn cheap to fly in the survey team. The new scale is only adding more inconsistency to the already inconsistent record. Why any scientist would do this baffles me. Why not have an F and EF rating? This way we get some consistency to the ratings and an injection of the "new" science. I thought the Gallatin, TN tor was an F4 with all walls collapsed on the foundation. The TX twister damage looks worse with at least one foundation totally swept clean of debris with only a rather large heavy duty fireplace left (which would probably survive an atomic blast). Looks F5 to me.

I've got this F-scale figured out:

F0/F1: Rating OK (though watch out for the bogus FGF F1 gustnadoes)
F2: Add +1 to the rating if some walls are down. If tornado was "slow" moving consider adding +2.
F3: The new "violent" tornado category. Always add +1 and consider +2 for particularly severe damage.
F4: The new rating for May 3, 1999 Moore, OK tornado.
F5: What the hell is that? 1. Mount St. Helens horizontal blast or 2. Evacuate area immediately to avoid radiation as it was nuked by Iran.

USING THE NEW ENHANCED FUJITA SCALE GUIDELINES...MAXIMUM WINDS WERE LIKELY IN THE 150 TO 160 MPH RANGE.[/b]

Likely? Likely much higher. Let me see. Hurricane Charley had 145 mph sustained winds and the homes in Punta Gorda didn't get flattened like those in TX. Andrew was stronger and while homes sustained severe damage they wern't picked clean. I might be comaparing an apple to an orange but wind is wind. I think the EF wind scale is a joke.