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by Tim Marshall P.E.

Meteorologist

In the Eye of the Storm: Perspective From an Engineer, Meteorologist and Storm Chaser

Presented at 2017 Tornado Summit Oklahoma City, OK February 14, 2017

1957 Began to position chase vehicles

April 21, 1967Oak Lawn, IL Tornado

1967 -Oak Lawn, IL news

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Oak Lawn Tornado Damage Destroyed mobile home park

April 21, 1967Oak Lawn Tornado Track

Rated F4

Traveled 16.2 miles @ 60 mph33 deaths

>1000 homes damaged

http://www.weather.gov/media/lot/events/1967_Apr_Tornadoes/OakLawn_Tornado_survey.pdf

April 21, 1967 barograph trace from Albright Middle School

Drops in pressure with Belvidere

and Oak Lawn tornadoes.

Marvin Zeaman

1969 - Won top award for tornado exhibit at science fair.

Tornado

1970 – Lubbock, TX Tornado

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1970 – Lubbock, TX Tornado 1970- Dr. Fujita surveyed the

tornado damage

http://www.lubbocktornado1970.com/pdf/LubbockTornadoes_TetsuyaFujita.pdf

1971- Fujita Scale

https://swco-ir.tdl.org/swco-ir/handle/10605/261888

Institute for Disaster Research was formed at TTU

Kiesling, Peterson, Mehta, Minor, McDonald

DR. TED FUJITA

and the SuperOutbreakApril 3-4, 1974

I attended his lecture at the

Univ. of Chicago 11-12-74319 fatalities, 5,484 injuries

1974- F5 Xenia, OH Tornado

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1974- F5 Xenia, OH Tornado

Worst damage occurred on Marshall Street !

1974 – N.I.U. Meteorology

Prof. Jack R. Villmow

1976 – First Tornado Damage Survey 1976 – Lemont, IL Tornado

I walked the

damagepath

1978 – TTU Graduate School Saw a tornado first day in TX

Edmonson, TX – May 27, 1978

1978 – TTU Graduate School

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April 10, 1979 - Dr. Peterson and I prepare to chase storms

April 10, 1979 – Wichita Falls Tornado

Mobile home park adjacent to Hwy 287

June 3, 1980Grand Island, NE Tornadoes

Did aerial and ground surveys

June 3, 1980Grand Island, NE Tornadoes

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June 3, 1980Grand Island, NE Tornadoes

June 3, 1980Grand Island, NE Tornadoes

http://www.depts.ttu.edu/nwi/Pubs/Rep

ortsJournals/ReportsJournals/D6-3-80-

Tor-GrandIsland.pdf

June 3, 1980 Grand Island, NE survey

House failure modes Paths of roof planks

June 3, 1980 Grand Island, NE Tornadoes

Aug. 1980 – TTU CE student

August 10, 1980- Hurricane AllenMy first hurricane chase

Day before

hurricane

Day of

hurricane

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I witnessed the power of hurricane-force winds

1980- I witnessed the power of storm surge

http://www.depts.ttu.edu/nwi/Pubs/ReportsJournals/ReportsJournals/D8-10-80-Hurr-Allen.pdf

April 12, 1981 Warren, OK

https://stormtrack.org/wordpress/wp-content/uploads/the-

mesocyclone-evolution-of-the-warren-oklahoma-tornadoes.pdf

May 22, 1981 – Binger, OK

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May 22, 1981 – Binger, OK May 22, 1981 – Binger, OK

http://www.depts.ttu.edu/nwi/Pubs/ReportsJournals/ReportsJournals/D5-22-81Tor-Binger.pdf

1982 – Storm Chase Manual

� Listed procedures on how to chase storms and film them at close range.

� NRC contract to study debris generated by tornadoes

https://stormtrack.org/wordpress/wp-content/uploads/storm-chase-manual-1998-edition.pdf

Classic Supercell

May 9, 1982 Dawn, TX May 16, 1982 Silverton, TX

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May 19, 1982 Pampa, TX #2 May 19, 1982 Pampa, TX #4

May 19, 1982 Pampa, TX #6

https://stormtrack.org/wordpress/wp-content/uploads/storm-scale-of-the-pampa-storm.pdf

May 19, 1982 Tornado Tracks

1983 – Haag Engineering Co. Ice Ball Launcher

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Making Ice BallsHAIL SIZE

(IN)DAMAGE THRESHOLD

1 Lightweight comp shingles

1-1/4 Heavy weight comp, wood shingles

1-1/2 Medium wood shakes

1-3/4 Concrete tiles, modified bitumen

2 Smooth built-up roofing, EPDM

2-1/2Ballasted built-up roofing, EPDM, metal panels

https://ams.confex.com/ams/pdfpapers/45858.pdf

FM 4473 – Ice impact test Wood and Comp Pictorials

http://haageducation.com/books-tools/

1986

STORMTRACK MAGAZINE

Lasted 25 years

Now online at:

http://www.

stormtrack.org

1986 - First “portable” computer

Getting SAO’s with my PCjr – 64K no hard drive, 8 pin dot

matrix printer and 300 baud modem.

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May 1, 1988 - Carson Eads Chase Van 1996- “TWISTER” movie

with star Bill Paxton At OKC premiere

with Don Burgess and Jim Bellville with Oprah Winfrey

Involved in the development of the new EF-scale

� Upgrades the original Fujita Scale using 28 damage indicators.

� Adopted by the NWS in 2007.

http://www.depts.ttu.edu/nwi/Pubs/FScale/EFScale.pdf

1978-2016 chase statistics

� ~ 800 chase days (2.1 years)

� ~ 400 days of severe storms (50%)

� ~ 300 tornadoes

� ~ 100 tornado days

� ~ 500,000 miles (625 mi/chase)

� ~ 10,000 hours chasing (416 day hours)

Does not include hurricane chases or air miles.

1978-2016 Tornado Days and Surveys

Birmingham UK Tornado Survey

My Tornado Library

� Over 30,000 slide images of Over 30,000 slide images of Over 30,000 slide images of Over 30,000 slide images of tornadoes, chasing, and damage.tornadoes, chasing, and damage.tornadoes, chasing, and damage.tornadoes, chasing, and damage.

� Thousands of hours of video and Thousands of hours of video and Thousands of hours of video and Thousands of hours of video and tape recordings of chases in tape recordings of chases in tape recordings of chases in tape recordings of chases in formats from Super8, VHS, SVHS, formats from Super8, VHS, SVHS, formats from Super8, VHS, SVHS, formats from Super8, VHS, SVHS, HiHiHiHi----8, MiniDV, and SD.8, MiniDV, and SD.8, MiniDV, and SD.8, MiniDV, and SD.

� Thousands of papers, books, and Thousands of papers, books, and Thousands of papers, books, and Thousands of papers, books, and newspaper articles on tornadoes.newspaper articles on tornadoes.newspaper articles on tornadoes.newspaper articles on tornadoes.

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Books, videos

and files

– oh my!

Chase logs and hand drawn maps are

kept in notebooks

Slides are labeled and sleeved

Tornado Room “Ring of Honor”

THE 2016TWIRL PROJECT

http://www.cswr.org

Tornadic Winds: In-situ and Radar measurements at Low levels (TWIRL)

5 pods in

SCOUT 3

Team: Brandon Molyneaux, Jacob DeFlitch, and Katie Griffith

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The instrumented pod cost 6K each

2016 TWIRL PROJECT

Dr. Josh Wurman Dr. Karen Kosiba3 SCOUTS

3 DOWS

Dr. Josh Wurman inside DOW-72016 TWIRL PROJECT

2016 TWIRL PROJECT

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SULPHUR, OKCHASE

MAY 9, 2016

4:05pI-35

WYNNEWOOD

SULPHUR

HWY

177

DAVIS Rt. 7

SCOUT 3

SM

4:05pI-35

WYNNEWOOD

SULPHUR

HWY

177

DAVIS Rt. 7

SCOUT 3

4:07 PM Multi-vortex

tornado SW

4:07PM – POD L deployed4:11pI-35

SULPHUR

HWY

177

DAVIS Rt. 7

SCOUT 3

1m

WYNNEWOOD

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4:11pI-35

SULPHUR

HWY

177

DAVIS Rt. 7

SCOUT 3

1m

WYNNEWOOD

4:15 PM Pod M deployed

4:18pI-35

SULPHUR

HWY

177

DAVIS Rt. 7

SCOUT 3

WYNNEWOOD

4:18pI-35

SULPHUR

HWY

177

DAVIS Rt. 7

SCOUT 3

WYNNEWOOD

4:17 PM POD N deployed4:19 PM Tornado crossed Meridian Rd.

The tornado went south of all 3 pods

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4:25 PM Tornado lifts and destroys house4:44 PM – Multi-vortex

tornado forms south

4:50p

I-35

HWY

177

DAVIS Rt. 7

SCOUT 3

WYNNEWOOD

SULPHUR

4:50p

I-35

SULPHUR

HWY

177

DAVIS Rt. 7

SCOUT 3

WYNNEWOOD

4:52 PM – Wedge just south 4:55 PM – Wedge just south

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Quickly deployed pod in front of wedge tornado

Thanks to Scott Peake

SCOUT 3

Reality duplicates HollywoodV O R T E X 2 S P E C I A L E D I T I O N

V

4:57p

I-35

SULPHUR

HWY

177

DAVIS Rt. 7

SCOUT 3

WYNNEWOOD

4:57p

I-35

SULPHUR

HWY

177

DAVIS Rt. 7

SCOUT 3

WYNNEWOOD

5:00 PM Tornado

approaching us. Pod hit.

1 m/s = 2.237 mph

89 mph

Courtesy of CSWR

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1 km

Courtesy of CSWR

1 km

Courtesy of CSWR

1 km

Courtesy of CSWR

1 km

Courtesy of CSWR

1 km

Courtesy of CSWR

1 km

78mph

Courtesy of CSWR

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1 km

Courtesy of CSWR

1 km

Courtesy of CSWR

1 km

Courtesy of CSWR

FIRST POD HIT FOR

CSWR

TORNADO TRACKS by

NWS

KATIE

TORNADO

9 MILES

LONG

21 MINUTES

RATED EF-4

SULPHUR

TORNADO

17 MILES

LONG

43 MINUTES

RATED EF-3

I-

3

5

OKC AreaDamage Surveys

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1999, 2003 and 2013 PATHS

1 SQ. MILE

May 3, 1999 – Moore, OK

Still images from video by Tim Marshall

117

Variation of damage: F0 to F5

118

F-scales overlaid on aerial photo

CRITICAL

CONNECTIONS

Problems with foundation attachment

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Typical connection of wall to slab

F indicates likely failure areas

Types of connections to slab

Straight-nailed studs pulled away from bottom plate (May 1999)

Studs pulled out from strapped bottom plate (May 1999)

Bottom plate had been secured with shot pins (May 1999)

Scrape in slab where cut nail moved (May 1999)

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Cut nails were all that was left of this house (May 1999)

I returned to Moore in August 1999 and examined 40 homes under construction…

� Five homes were bolted to their foundations (12.5%).

� Six homes were strapped to their foundations (15%).

� 29 homes were nailed or pinned to their foundations (72.5%).

Building Code Requirements

� Wood bottom plates on exterior walls shall be bolted to the foundations a maximum of 6 feet apart.

� A nut with washer must be tightened on each bolt.

� There shall be a minimum of TWO bolts per plate section.

130

Anchor Bolt Placement

12.5% foundations had bolts ( Aug. 1999) Properly bolted wall plates (Aug. 1999)

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15% of foundations had straps (Aug. 1999) Oops. Strap outside wall insulation board (Aug. 1999)

Oops #2 – Straps outside of insulation board (Aug. 1999)

72.5% of walls were to be nailed or pinned to their foundations (Aug. 1999)

Shot pinned wall plate to slab (Aug. 1999)Use of cut nails on perimeter walls was a code violation (Aug. 1999)

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How deep does a cut nail extend into the slab?

About a half inch if it doesn’t spall the concrete!

Problems with wall attachment

Let-in brace helps stiffen wall (Aug. 1999) Oops. What you don’t see WILL hurt you.

(Aug. 1999)

Solid sheathing help stiffens wall corner in lieu of let-in brace. But what about the pink stuff? (August 1999)

Problems with the attachment of roof framing

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Typical rafter-top plate connection that performs poorly when it is uplifted

New house built after it was destroyed by tornado. Note nails through corner of top plate (Aug. 1999)

One house had clips between rafters and top plate (Aug. 1999)

148

Brick toppled suction side – ties not engaged

149

How ties are to be installed per FEMA

TTU publication resulted from the damage survey

http//www.depts.ttu.edu/nwi/Pubs/Reports/Journals/ReportsJournals/Tornadoes-of-OKC-may-3-1999.pdf

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Survey Results (1999)

� Many homes were poorly built and thus, provided more flying debris.

� Many homes failed at the wall/foundation or roof/wall connections.

� A number of homes built after the tornado contained building code violations.

� The next violent tornado will do just as much if not more damage. May 20, 2013

Houses south of Plaza Towers School

Houses swept clean south of Plaza Towers

Destroyed

home

2013

Cut nails on exterior walls Cut nails on exterior walls

Destroyed

home

2013

Cut nails on interior walls Shot pins on exterior walls

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Roof failures (2013) Roof failures (2013)

Roof failures (2013)

I returned to Moore in December 2013 and examined 20 homes under construction…

� All 20 homes were bolted to their foundations (100%) !

� No homes had been strapped to their foundations !

� 4 homes had shelters ! (3 above ground, 1 below ground) This was above-code.

� 3 homes had rafter clips ! This was above-code.

Inspection Comparison

AUGUST 1999

DECEMBER 2013

Bolted perimeter 12.5 % 100 %Strapped perimeter 15 % 0%Nailed or pinned

perimeter72.5% *

*Bolted plates frequently had added nails or pins.

A BIG IMPROVEMENT, right ?

DEC. 2013

Bolts with no nuts or washers throughout entire house

“A nut and washer shall be tightened on each anchor bolt.”

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DEC. 2013

Bolt under cut stud. No washer

Bolt outside of plate

Bolt outside of plate

Nail

“Studs shall have full bearing on nominal 2x.”

Of the 20 homes examined in December 2013…

� All homes had anchor bolts. However…

� 25 % of homes had nuts and washers properly tightened on centered bolts

� 75 % of homes had certain bolts with no nuts or washers or bolts were installed too close to the edges of the plates.

All 20 inspected homes had solid sheathing (Dec. 2013)

But wind uplift resistance is

poor

Rafters were toe nailed to top plates per code (Dec. 2013)

3 of 20 houses had rafters clipped to top plates (above-code) 2013

4 of 20 homes had shelters

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So what was learned after three major tornado

disasters in the OKC area:

� Homes have changed from a variety of perimeter connections to bolts (+).

� However, most homes (75%) had problems with the bolted plates (i.e. no nuts/washers, cut plates, cut studs, etc.) (-)

� All homes had solid exterior sheathing (+)

� 3 of 20 homes had rafter clips (+)

� 4 of 20 homes had shelters (+)

Many thanks to:

� National Science Foundation

� Center for Severe Weather Research

� National Weather Service

� Storm Prediction Center

� City of Moore, OK.

� Haag Engineering Co.

email: tmarshall@haagglobal.com

THE END