2013-05-15 MISC: TX

[Shawn Schuman]

Here's the radar loop. I wanted to use a two-panel BR/SRV view but for some reason it only wanted to record the left panel, so I had to do them one at a time. Still, you can see it quite clearly in the velocity loop. Make sure you play in HD, otherwise it's hard to make out.

 

[Derek Weston]

0-1km SRH at roughly the time of the Granbury tornado:

There was a small area of 400 m2s2 a bit later but it was further east. As for the strange tornado motion, I'm uploading a radar loop on Youtube where you can see it better, I'll post when it's done. It pretty clearly occluded/cycled a couple of times, including once in between Granbury and DeCordova and once more near Cleburne/Rio Vista.

Ah. Perhaps I'm forgetting my time frame, at any rate, some significant numbers in vicinity of location. (wasn't it around 02z that the storm was at its strongest, though?)

Dissecting a 0z sounding would probably be helpful, could derive these numbers more meaningfully there.

 

[Albert Rodriguez]

Albert, in the last minute of your video it almost looks like there is one more than one tornado beneath the meso, was that your impression as well? See 4:20-4:48 for example.

I imagine that thing was multi-vortex like 11-7-11 near Fort Cobb.

 

[Shawn Schuman]

Whoops, looks like I was slightly off as well, Derek. The Granbury tornado occurred right around 01z, the Cleburne tornado appears to have been at its strongest just a little past 02z.

In any event, 00z FWD sounding paints a similarly impressive picture. Speed shear wasn't overwhelming, but turning was fantastic.

 

[Jason Harris]

Clean slabs are to my recollection the standard for old school F5 damage, and I thought that was the general threshold for Ef-5 as well, so for the survey in TX, what subtle distinctions led to EF-4?
__
House completely destroyed with only the slab left -
Granbury, Tx
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http://www.srh.noaa.gov/fwd/?n=tornadoes051513

Perhaps the construction qualities? So it wasn't reinforced well enough to merit EF-5?

Note that LB is 165 and 220 UB for 1-family residence--perhaps they go with the (EXP, expected?) 200 and thus high-end Ef-4 since there were no high rises to inspect for higher winds?:
http://www.spc.noaa.gov/efscale/2.html

 

[Brian McKibben]

How is this not EF-5 damage? The 2x4 (or 2x6) was secured to the foundation with large bolts. There is nothing left.

 

[Shawn Schuman]

In at least one of the photos you can see straight nails, and what anchor bolts are there seem to be very widely spaced, so I'd imagine it's construction quality. Also, the debris was "swept away" in some instances, but it seems to have been mostly piled up a short distance from the homes and left in large pieces. That said, unless I missed it I believe it's still a preliminary rating so there's an opportunity to upgrade if they feel it's necessary. I think EF4 (probably high-end) seems to be a good call from what I've seen so far, though.

Edit: The same sort of thing happened with the Chickasha and Goldsby tornadoes on 5/24/11. The homes were obliterated and swept clean, but construction quality was pretty poor. They may very well have been EF5s, but there wasn't much evidence to support it.

 

[Dan Robinson]

They appear to be modern well-built homes. Here is the Street View of the 'before' scene (at least according to the marker on NWS site):

https://maps.google.com/maps?q=gran...a5tdQgqg9tGWenjn0tHfMA&cbp=12,191.63,,0,17.31

 

[Shawn Schuman]

Look at the photos though, and remember it requires "superior construction" for EF5. There's not much in the way of anchoring from what I can see. Appearances can be deceptive when it comes to the construction quality of a home. It's possible they'll find evidence of EF5 if the survey is still ongoing, but I don't think the photos I've seen pass the test. 'Course, I'm not a structural engineer either.

 

[Tim Supinie]

How is this not EF-5 damage? The 2x4 (or 2x6) was secured to the foundation with large bolts. There is nothing left.

Also, the wood flooring is still there. Either the flooring is uncommonly well-anchored or the walls weren't tied down very well. I'm going to go with the second one.

 

[Mike Smith]

I offer some comments about last night's tornadoes (especially the similarity to Greensburg) on my blog here: http://meteorologicalmusings.blogspot.com/2013/05/comments-on-last-nights-tornadoes.html

There is a comment I'd like to make to the chasing/meteorological community that I think will be useful after last night's tornadoes and with more tornadoes looming this weekend. In my book, Warnings, I comment how language "inverts" when meteorologists and chasers talk among themselves (i.e., "I had a great day!" = I got great photos of an impressive storm). There is nothing wrong with this and I do it myself.

However, on Facebook today, there are a couple of comments that could be read as "triumphant" language. Because Facebook is public, I suggest caution when writing about storms. No matter how great the chase was, people died. So, please, try to be sensitive in what you write. We don't want to inadvertently give non-chasers the wrong impression about us.

 

[StormScotter]

The fact the hardwood's still there is probably why it's rated EF-4. If the foundation had been wiped clean to the concrete, the EF-5 would make more sense.

 

[Kem Poyner]

Albert's video really shows amazing structure towards the end. Had it been daytime and the trees and signs were not in frame....wow, what a vault! The audio on the video reminds me of how I chuckle when I hear that New tone blarring when an upgrade to Tornado warning is needed. I know it must be necessary to activate NOAA radio alarms, but the tone seems to go on forever followed by a long pause of silence be for the actual voice starts. 15 seconds is along time to wait for the information to be heard when you are in the path. Perhaps Severe storms and tornadic warnings should have a different tone?

 

[Mike Johnston]

Just watching this event from afar, it looks like the NWS did a very good job with its watches and warnings. Perhaps the initial Day 1 outlook didn't completely foresee the local outbreak, but SPC did upgrade the tornado probabilities later in the day and then correctly delineated a tornado watch area. The local warnings were outstanding, being specific, descriptive and timely (I think much better than any "impact based warning" under the new regime would have done.)

 

[Brandon Jenkins]

We observed a very similar behavior from the Millsap storm in terms of tornado motion/meso occlusion although I did not note it's appearance on radar at the time. We were within 1/2 mile to 1/4 mile of the millsap tornado for approx 4-5 minutes and upon arriving on the tornado we quickly realized it was moving NW as opposed to the E/SE as would typically be expected. At the time I was unsure if this was due to the tornado roping out and taking on a more erratic pattern as it reached the end of its life cycle or if it could have been caused by a sudden occlusion of the mesocyclone back into the storm. Did anyone else note this? For reference, we approached this tornado on the exact E/W road it was crossing and it moved steadily N/NW throughout the entire duration that we observed it.