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In the Eye of the Storm: Perspective From an Engineer, Meteorologist and Storm Chaser
by Tim Marshall P.E. Meteorologist
Presented at 2017 Tornado Summit Oklahoma City, OK February 14, 2017
1957 Began to position chase April 21, 1967 vehicles Oak Lawn, IL Tornado
1967 -Oak Lawn, IL news
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Oak Lawn Tornado Damage Destroyed mobile home park
April 21, 1967 April 21, 1967 barograph trace Oak Lawn Tornado Track from Albright Middle School
Rated F4 Traveled 16.2 miles @ 60 mph 33 deaths >1000 homes damaged Marvin Zeaman Drops in pressure with Belvidere http://www.weather.gov/media/lot/events/1967_Apr _Tornadoes/OakLawn_Tornado_survey.pdf and Oak Lawn tornadoes.
1969 - Won top award for tornado exhibit at science fair. 1970 – Lubbock, TX Tornado
Tornado
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1970- Dr. Fujita surveyed the 1970 – Lubbock, TX Tornado tornado damage
http://www.lubbocktornado1970.com/pdf /LubbockTornadoes_TetsuyaFujita.pdf
Institute for Disaster 1971- Fujita Scale Research was formed at TTU
https://swco-ir.tdl.org/swco- ir/handle/10605/261888
Kiesling, Peterson, Mehta, Minor, McDonald
DR. TED FUJITA and the 1974- F5 Xenia, OH Tornado SuperOutbreak April 3-4, 1974
I attended his lecture at the 319 fatalities, 5,484 injuries Univ. of Chicago 11-12-74
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1974- F5 Xenia, OH Tornado 1974 – N.I.U. Meteorology
Prof. Jack R. Villmow
Worst damage occurred on Marshall Street !
1976 – First Tornado Damage Survey 1976 – Lemont, IL Tornado
I walked the damage path
1978 – TTU Graduate School 1978 – TTU Graduate School Saw a tornado first day in TX Edmonson, TX – May 27, 1978
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April 10, 1979 - Dr. Peterson and I April 10, 1979 – Wichita Falls Tornado prepare to chase storms
Mobile home park adjacent to Hwy 287
June 3, 1980 June 3, 1980 Grand Island, NE Tornadoes Grand Island, NE Tornadoes
Did aerial and ground surveys
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June 3, 1980 June 3, 1980 Grand Island, NE Tornadoes Grand Island, NE Tornadoes
http://www.depts.ttu.edu/nwi/Pubs/Rep ortsJournals/ReportsJournals/D6-3-80- Tor-GrandIsland.pdf
June 3, 1980 June 3, 1980 Grand Island, NE survey Grand Island, NE Tornadoes
House failure modes Paths of roof planks
Aug. 1980 – TTU August 10, 1980- Hurricane Allen My first hurricane chase CE student Day before hurricane
Day of hurricane
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I witnessed the power of 1980- I witnessed the hurricane-force winds power of storm surge
April 12, 1981 Warren, OK
http://www.depts.ttu.edu/nwi/Pubs/ReportsJournals/ ReportsJournals/D8-10-80-Hurr-Allen.pdf
May 22, 1981 – Binger, OK
https://stormtrack.org/wordpress/wp-content/uploads/the- mesocyclone-evolution-of-the-warren-oklahoma-tornadoes.pdf
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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 Classic Supercell
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
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 May 19, 1982 Tornado Tracks
https://stormtrack.org/wordpress/wp- content/uploads/storm-scale-of-the-pampa-storm.pdf
1983 – Haag Engineering Co. Ice Ball Launcher
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HAIL Making Ice Balls SIZE DAMAGE THRESHOLD (IN) 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 Ballasted built-up roofing, EPDM, metal 2-1/2 panels
https://ams.confex.com/ams/pdfpapers/45858.pdf
FM 4473 – Ice impact test Wood and Comp Pictorials
http://haageducation.com/books-tools/
1986 - First “portable” computer 1986 STORMTRACK MAGAZINE
Lasted 25 years Now online at: http://www. stormtrack.org 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 1978-2016 chase statistics of the new EF-scale
Upgrades the ~ 800 chase days (2.1 years) original Fujita ~ 400 days of severe storms (50%) Scale using 28 damage ~ 300 tornadoes indicators. ~ 100 tornado days Adopted by the ~ 500,000 miles (625 mi/chase) NWS in 2007. ~ 10,000 hours chasing (416 day hours) http://www.depts.ttu.edu/nwi/Pubs/FScale/EFScale.pdf Does not include hurricane chases or air miles.
1978-2016 Tornado Days and Surveys My Tornado Library
Over 30,000 slide images of tornadoes, chasing, and damage. Thousands of hours of video and tape recordings of chases in formats from Super8, VHS, SVHS, HiHiHi-Hi---8,8, MiniDV, and SD.
Birmingham UK Tornado Thousands of papers, books, and Survey newspaper articles on tornadoes.
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Chase logs and hand drawn maps are Books, videos and files kept in notebooks – oh my!
Tornado Room “Ring of Honor” Slides are labeled and sleeved
Tornadic Winds: In-situ and Radar measurements at Low levels (TWIRL)
5 pods in THE 2016 SCOUT 3 TWIRL PROJECT
http://www.cswr.org Team: Brandon Molyneaux, Jacob DeFlitch, and Katie Griffith
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The instrumented pod cost 6K each 2016 TWIRL PROJECT
3 DOWS
Dr. Josh Wurman Dr. Karen Kosiba 3 SCOUTS
Dr. Josh Wurman inside DOW-7 2016 TWIRL PROJECT
2016 TWIRL PROJECT
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I-35 4:05p HWY SULPHUR, OK 177 WYNNEWOOD CHASE SCOUT 3 MAY 9, 2016 SM DAVIS Rt. 7 SULPHUR
4:07 PM Multi-vortex I-35 4:05p tornado SW HWY 177
WYNNEWOOD SCOUT 3
DAVIS Rt. 7 SULPHUR
4:07PM – POD L deployed I-35 4:11p HWY 177
WYNNEWOOD
SCOUT 3
1m DAVIS Rt. 7 SULPHUR
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I-35 4:11p 4:15 PM Pod M deployed HWY 177
WYNNEWOOD
SCOUT 3
1m DAVIS Rt. 7 SULPHUR
I-35 4:18p I-35 4:18p HWY HWY 177 177
WYNNEWOOD WYNNEWOOD
SCOUT 3 SCOUT 3
DAVIS Rt. 7 SULPHUR DAVIS Rt. 7 SULPHUR
4:19 PM Tornado crossed Meridian Rd. 4:17 PM POD N deployed
The tornado went south of all 3 pods
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4:44 PM – Multi-vortex 4:25 PM Tornado lifts and destroys house tornado forms south
HWY HWY 177 4:50p 177 4:50p
WYNNEWOOD WYNNEWOOD
SCOUT 3 SCOUT 3
SULPHUR SULPHUR DAVIS Rt. 7 DAVIS Rt. 7 I-35 I-35
4:52 PM – Wedge just south 4:55 PM – Wedge just south
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Quickly deployed pod in Reality duplicates Hollywood front of wedge tornado V O R T E X 2 S P E C I A L E D I T I O N
SCOUT 3
Thanks to Scott Peake
V
HWY HWY 177 4:57p 177 4:57p
WYNNEWOOD WYNNEWOOD
SCOUT 3 SCOUT 3
SULPHUR SULPHUR DAVIS Rt. 7 DAVIS Rt. 7 I-35 I-35
Courtesy of CSWR 1 m/s = 2.237 mph 5:00 PM Tornado approaching us. Pod hit.
89 mph
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Courtesy of CSWR Courtesy of CSWR
1 km 1 km
Courtesy of CSWR Courtesy of CSWR
1 km 1 km
Courtesy of CSWR Courtesy of CSWR
78mph
1 km 1 km
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Courtesy of CSWR Courtesy of CSWR
1 km 1 km
Courtesy of CSWR FIRST POD HIT FOR CSWR
1 km
TORNADO TRACKS by NWS
I- 3 OKC Area 5 Damage
KATIE SULPHUR TORNADO TORNADO Surveys 9 MILES 17 MILES LONG LONG 21 MINUTES 43 MINUTES RATED EF-4 RATED EF-3
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1999, 2003 and 2013 PATHS May 3, 1999 – Moore, OK
1 SQ. MILE
Still images from video by Tim Marshall
Variation of damage: F0 to F5 F-scales overlaid on aerial photo
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CRITICAL CONNECTIONS Problems with foundation attachment
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Types of connections to slab Typical connection of wall to slab
F indicates likely failure areas
Straight-nailed studs pulled away from Studs pulled out from strapped bottom plate (May 1999) bottom plate (May 1999)
Bottom plate had been secured with Scrape in slab where cut nail moved shot pins (May 1999) (May 1999)
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Cut nails were all that was left of this I returned to Moore in August 1999 and house (May 1999) 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 Anchor Bolt Placement 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.
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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)
72.5% of walls were to be nailed or pinned to their foundations (Aug. 1999)
Oops #2 – Straps outside of insulation board (Aug. 1999)
Use of cut nails on perimeter walls Shot pinned wall plate to slab (Aug. 1999) was a code violation (Aug. 1999)
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How deep does a cut nail extend into the slab? Problems with wall attachment
About a half inch if it doesn’t spall the concrete!
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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New house built after it was destroyed by tornado. Note Typical rafter-top plate connection that nails through corner of top plate (Aug. 1999) performs poorly when it is uplifted
One house had clips between rafters Brick toppled suction side – ties not engaged and top plate (Aug. 1999)
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How ties are to be installed per FEMA
TTU publication resulted from the damage survey
http//www.depts.ttu.edu/nwi/Pubs/Reports/Journals/Reports 149 Journals/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 Houses swept clean south Towers School of Plaza Towers
Destroyed Destroyed home home 2013 2013
Cut nails on exterior walls Cut nails on exterior walls Cut nails on interior walls Shot pins on exterior walls
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Roof failures (2013) Roof failures (2013)
I returned to Moore in December 2013 Roof failures (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.
DEC. 2013 Inspection Comparison
AUGUST DECEMBER 1999 2013 Bolted perimeter 12.5 % 100 % Strapped perimeter 15 % 0% Bolts with no nuts or washers Nailed or pinned throughout entire house perimeter 72.5% * *Bolted plates frequently had added nails or pins.
A BIG IMPROVEMENT, right ? “A nut and washer shall be tightened on each anchor bolt.”
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DEC. 2013 Of the 20 homes examined in December 2013…
All homes had anchor bolts. However… Nail 25 % of homes had nuts and washers Bolt under cut properly tightened on centered bolts stud. No washer 75 % of homes had certain bolts with no “Studs shall have full bearing on nominal 2x.” nuts or washers or bolts were installed too close to the edges of the plates.
Bolt outside Bolt outside of plate of plate
All 20 inspected homes had Rafters were toe nailed to top solid sheathing (Dec. 2013) plates per code (Dec. 2013)
But wind uplift resistance is poor
4 of 20 homes had shelters 3 of 20 houses had rafters clipped to top plates (above-code) 2013
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So what was learned after three major tornado Many thanks to: disasters in the OKC area:
Homes have changed from a variety of National Science Foundation perimeter connections to bolts (+). Center for Severe Weather Research However, most homes (75%) had problems National Weather Service with the bolted plates (i.e. no nuts/washers, cut plates, cut studs, etc.) (-) Storm Prediction Center All homes had solid exterior sheathing (+) City of Moore, OK. 3 of 20 homes had rafter clips (+) Haag Engineering Co. 4 of 20 homes had shelters (+)
THE END
email: [email protected]
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