Chat with Tim Marshall: 2/16/00

Tim Vasquez Our guest today is Tim Marshall, which I'm sure everyone recognizes here as the editor of Stormtrack. Tim is also a structural engineer for Haag Engineering and does storm/tornado damage surveys. We will run this as a formal conference for the first 30 minutes, then I will loosen things up and you can chat as you wish... however I ask that for the following 30 minutes we direct all questions to Tim Marshall. I will prompt each one of our guests, working down the list, for any questions they have for Tim. Please give him a moment to respond, then when he's done I'll prompt the next person. I will now unmoderate the list.

Dennis Gabler No question at this time, thanks.

Keith Minor I've been looking for articles such as your "Cap Boom or Bust". Do you have plans to write more "qualitative articles"? Mixing tech with your personal experience out on the field?

Tim Marshall (TPM) I hope to write more such articles in the future. The dryline has always been fickle to me.

Matt Sellers Tim, I saw that you were around the Elbert/Olney TX tornado of 4/30/000... what was your take on that storm?

TPM I punched the core from the NW as I was coming in from SPS. I saw the HP structure and proceeded SW on 79. Seeing the wrapping rain curtains I decided to stay put. Little did I know Jim LaDue and wife were ahead of me. They punched the wrapping curtains and saw a large wedge tornado. I didn't know the wrapping curtains were only rain and I admit I don't like the thought of "seeing whats back there". I saw a small tornado form on the inflow side just W of Olney. Did anyone else see it?

MoKanChaser I'm new to this and my questions may not be very knowledgable, but I do have one... are survey techniques standardized in some way or is it pretty much left up to individual surveyors to rate storm damage?

TPM It's left up to the individual surveyors. I will be writing an article about the F-scale in the April issue of ST and how I use it. I will also be presenting a talk at the NWA meeting at the end of March on the use and abuse of the F-scale.

Shane Adams On March 28 of last year, how did you arrive at your target for that day? Did you have another destination in mind further NW of Ft Worth and get "turned back" towards Ft Worth because of the storm, or was Ft Worth your original target?

TPM My forecast was SPS. I got on a storm near Bowie and as soon as I saw the cirrus coming in I became concerned. Second I couldn't see much inflow wind. The last thing I wanted was to get "nerded from behind" so I listened carefully to the radio! As soon as I heard the severe thunderstorm warning for Parker Co (just west of FTW) I drove south on Rt 287. Then I encountered strong EAST winds, much better inflow. I broke through the FFD and got brief golfball hail. As soon as I saw the storm structure -- nice wall cloud and tail, I knew I made the right choice. However, I heard about two tornado warnings on the Bowie storm, so I questioned my decision -- briefly. Sometimes I'm lucky and make the right choice.

Robert Dale Back to damage... is there any realistic shot at getting consistent damage evaluations from us common folk, without hiring an engineer to go with us? Is there enough out there to quickly (and ACCURATELY) train?

TPM I hope to write a booklet on assessing damage next year after ST ends. Buildings have so many variations in construction. Just remember that BUILDING CODES are the "goal". Most buildings are designed for 80-100 mph winds. They get into trouble quickly with winds above that. So, rating damage is one thing -- figuring failure wind speeds is another. To me the F-scale is two scales. Anyone can rate building damage F-0 to F-5. But what's the failure wind speed? For that, you have to know something about how the building was constructed. We are finding out that F-scale winds are too high, especially for F-3 and greater. Winds of greater than about 150 mph can wipe out the average wood-framed house.

Scott Kampas KB9VVP What is your idea on the future of the F-scale? Any possible upgrades or even a replacement in the next generation?

TPM There are meetings on this very issue coming up in March. I am for keeping the F-scale and just modifying the failure wind speeds. Other people, I know, want to do away with the F-scale. But, I don't think that is possible. I'll be talking more about this in Des Moines at the NWA meeting.

Deborah I am new at this, was wondering what the long term forecasts look like for this years spring storm season.

TPM I don't know what is going to happen. I really don't believe long term models. Even in a "lean" year there are going to be a few good chase days. SO, I just hope I can pick 'em. I don't believe any correlation exists between El Nino and tornadoes.

John-SCOA How come Illinois sees squall lines more so than supercells?

TPM I wondered why too, for many years growing up in Illinois. Squall lines result from "line-lifting" of warm air over cold air. Here in the southern plains, the dryline acts to "point-lift" unstable parcels of air. This tends to lead to more isolated storms.

Jon Person Are you aware of any new approaches to sampling the atmosphere? Or, are there plans to increase the density and frequency of daily soundings?

TPM Soundings are still done the old fashioned way and I too don't like that. I want more soundings and more closely spaced sites. So far the technology (satellite) hasn't been able to give reliable results. Maybe Tim Vasquez will put this on his project list.

Bud Younke Getting back to damage surveys Tim, is there a reliable way other than historical record to determine the quality of construction in an event that is not total, say just above failure point.

TPM Yes, first it depends on how the building is anchored to the foundation and what type of foundation it has. F-scale is usually rated for houses. So it helps if houses have some uniformity in construction, good or bad. Houses on blocks, bricks, or pier and beam foundations have little to no anchorage and are easily displaced in winds of 60-100 mph. In contrast, houses on concrete perimeter or concrete slab foundations CAN be attached better using steel anchor bolts. So check how well a house is anchored.

Laura Duchesne Since I just got here, I can't think of a question at the moment... but, have you read Erik Rasmussen's "Tornado Damage Assessment" paper, dated awhile back? I tend to agree with Erik that all structures have different strengths and it will either make the tornado more or less severe. Do you agree with this?

TPM Gee, I'd love to see the paper. Erik and I used to chase together at TTU. He is right in that there are so many variations and combinations in building construction. So unless homes have some uniformity in construction, it would be difficult to compare them.

Laura Duchesne What is it like chasing with him?

TPM Erik has an incredible instinct for sniffing out tornadoes. I was glad to chase with him for the three years while he was at TTU.

Mike Which to you is more enjoyable, chasing alone or with someone?

Tim I like both (but not at the same time). Chasing by myself without all the gadgets is fun as it presents more of a challenge -- YOU AGAINST THE STORM. Chasing in the CHASEMOBILE is also fun. We have sooooo much information. It's almost like CHEATING. Some people think it's like fishing with a BASSOMATIC.

Mike in Denver I'm sure this has been asked before, I'm a little late, but what has been your most challenging or bizarre chase?

TPM There are many challenging chases. But one day Carson Eads and I were in Post, TX in clear postfrontal clear skies when we heard about a wall cloud on a storm near Mineral Wells. It was 2.5 hours away. We had nothing to lose and figured we could get a second storm and sure enough we did and filmed 4 tornadoes.

RainCripps I was wondering, I am having trouble with getting back into school so I decided to start chasing in the meantime. Who if anyone should I hook up with to start chasing?

TPM Write up a little biography and send it to me and I'll put this in ST. Also, get on the Who's Who list at ST online. Read all you can on the subject. There are a lot of great sites on the Internet. I would definitely recommend chasing with someone until you feel comfortable. You can E-mail me at .

Shannon Key I am always really nervous about lightning when chasing. I'm a little surprised it hasn't "gotten" anyone yet. What are your feelings about it? Do you see it as an acceptable risk?

TPM I am very concerned about lightning. It's the #2 hazard, second only to driving. I've had too many close calls and I now prefer to stay in my car when filming when lightning is sighted. We must be careful. Some chasers (like Gene Moore) have been hit indirectly.

Tim Samaras I am going to miss the paper version of ST. Has there been anyone approaching you to continue the ST on paper?

TPM No. In fact subscribership has dropped in half since 1997 and this tells me the Internet has won. It's too expensive to print and takes a lot of my spare time. Al Moller agrees and said he'd pay twice as much for it. Tim Vasquez and I will try to improve ST online. Maybe we can extend the magazine to "online".

Laura Duchesne What about those who get ST but have no Internet access?

TPM As far as getting Internet access I was amazed that even small libraries in Kansas have access.

Shane Adams When was your first tornado (chased?)

TPM My first tornado I chased was an accident. It was May 28, 1978. I was heading to Lubbock, my first day in Texas to attend TTU, when a tornado nearly got me. WHAT AN OMEN. I'll have more about this in the last issue of ST.

Keith Minor I know several hard core chasers who go out about the same time every year. I think Chuck Doswell goes out three weeks end of May beginning of June. Would the last two weeks of May be a good default time to head out?

TPM The best time to chase is the end of May through mid-June. I take my three week annual chase vacation during this time.

MoKanChaser I saw a program about fitting new structures with these little gadgets that are attached between trusses and frames which greatly increase the roof's ability to withstand high winds [hurricane clips]. Are you aware if older homes can be retrofit in some way to make them more "wind worthy"?

TPM It's very difficult to retrofit an existing house. It's best to "harden" an interior closet or pantry. The site is excellent. DO check it out.

Tim Vasquez OK, that does it for this conference... I now turn it over to Tim Marshall

TPM Say, this was fun. Let us do it again.

Shane Adams I'm in.

Matt Sellers Yes...

Tim Vasquez Sounds good to me... the gang has the floor

Laura Duchesne That was interesting Tim, thanks. And Tim and Tim: great job on the ST web site! Well done!

Tim Vasquez Thanks

Tim Marshall I'd like to get David Hoadley on line. What do you think?

MoKanChaser woo hoo ... thank you, Tim ... very nice

Tim Vasquez Definitely, Tim

John-SCOA I would like to thank both Tim's for this. It was really fun.

Shane Adams Tim & Tim: nice job coordinating so many folks and making sure everyone had a turn.

ScottKampasKB9VVP You have my two thumbs up

Tim Vasquez Geez, the questions were EXCELLENT

Tim Marshall Tim Marshall logging out

MoKanChaser e-beers all around ...

Tim Vasquez Take care Tim

Laura Duchesne This was very well planned... great chat.

Matt Sellers later, Tim M.

Laura Duchesne Good night Tim and thanks!

John-SCOA cya Tim

MattSellers happy chasing...

Shane Adams it's like !) Questions LIVE!!!

Matt Sellers and thanks for an interesting chat

Shane Adams 10

Mike Good luck in 2001

TimMarshall has Quit(QUIT: )

Return to main page