Tim Marshall - Academia.edu (original) (raw)

Papers by Tim Marshall

nadoes Experiment-II (VORTEX2) field project was conducted in the spring of 2009 and 2010 (Wur-ma... more nadoes Experiment-II (VORTEX2) field project was conducted in the spring of 2009 and 2010 (Wur-man et al., 2010).1 The size and scope of the Verification of the Ori-gins of Rotation in Tornadoes Experiment-II (VOR-TEX2) field project (Wurman et al., 2010) required accurate forecasts to be made in order to plan the mission of the day and set up for future missions on following days. In 2009, the steering commit-tee was responsible for making the forecasts with input from the VOC. Each member of the steering committee would take turns producing the brief-ing for the daily morning PI mission planning-meeting. VORTEX2 utilized an armada of 35-40 vehicles with a variety of mobile observ-ing equipment. More than 100 scientists, students and media traveled over much of the Great Plains during the project. Although successful forecasts were made, the amount of time required of the steering commit-tee to create forecasts distracted from other mis-sion planning duties. To remove this distract...

On 31 May 2013, an intense, multiple-vortex tornado meandered through sparsely populated areas ne... more On 31 May 2013, an intense, multiple-vortex tornado meandered through sparsely populated areas near El Reno, Oklahoma (Fig. 1). This exceptionally wide tornado had a complex path, changing rapidly in both speed and direction (Fig. 2). The tornado killed eight people, all in vehicles, including three severe storm researchers (NWS, 2013). Storm survey teams traveled to the area the next day and rated 257 DIs (damage indicators) using the EF (Enhanced Fujita) scale developed by the Wind Science and Engineering Center (WSEC, 2006). Survey teams also documented damage to 344 non-standard DIs which included 112 oil tank batteries. The maximum damage rating was determined to be EF3. Total path length was 26.2 km. In addition, the tornado was well sampled at close range by the University of Oklahoma’s Rapid-Scan, X-band, Polarimetric, mobile Doppler radar (RaXPol). The radar obtained high temporal and spatial resolution velocity data indicating instantaneous winds in excess of 130 m s-1 clo...

The author conducted aerial and ground damage surveys along the Florida and Alabama coasts after ... more The author conducted aerial and ground damage surveys along the Florida and Alabama coasts after Hurricane Ivan. The purpose of these surveys was to: 1) determine the height of the storm surge, 2) acquire wind velocity data, 3) determine the timing of each, and 4) assess the performance of buildings exposed to wind and water effects. Particular emphasis was placed on delineating wind and water damage. A similar study has just been published by FEMA (2005). The author rode out Hurricane Ivan near Pensacola, FL then conducted hundreds of site specific inspections the year following the hurricane. Most buildings examined were wood-framed structures. Remaining buildings consisted of concrete masonry as well as multi-story, steel-reinforced, concrete structures. Various building failure modes were observed. Typically, wind exploited poorly anchored or attached roofs and vinyl siding whereas wave action undermined, collapsed and destroyed buildings near the coast. Wind damage generally be...

On May 22, 2011, a large and violent tornado struck southern portions of Joplin, MO. According to... more On May 22, 2011, a large and violent tornado struck southern portions of Joplin, MO. According to the National Oceanic and Atmospheric Administration (NOAA, 2011), the tornado killed 158 people and injured more than 1000 people. The tornado was rated EF-5 on the Enhanced Fujita Scale, with maximum winds exceeding 89 ms -1 (200 mph). During the week following the tornado, the author conducted aerial and ground surveys of the damage. Surveying the damage was a challenge due to the large numbers of damaged or destroyed buildings (about 8,500 structures) as well as the rapid clean-up that was ongoing. Certain buildings were being demolished with heavy equipment within days after the tornado. Therefore, the author decided to select a sample of 14 buildings constructed with concrete masonry unit (CMU) walls. CMU buildings typically had a combination of loadbearing walls (grouted cells reinforced with steel rebar) and non load-bearing walls (no grouted cells or rebar). Walls typically fail...

A tornado outbreak occurred during the evening of 26 December 2015 across portions of North Texas... more A tornado outbreak occurred during the evening of 26 December 2015 across portions of North Texas. In all, there were 12 confirmed tornadoes in 8 counties. Unfortunately, 13 people lost their lives and there were numerous injuries as two of the strongest tornadoes struck Dallas-Fort Worth (DFW) suburbs. Most fatalities occurred in vehicles near the Interstate 30/George Bush Turnpike interchange in Garland, Texas (Fig. 1). Damage survey teams were dispatched the next day by the Fort Worth National Weather Service (FWD) to determine characteristics of the tornado paths. The survey team utilized the Enhanced Fujita (EF) scale to rate damage severity developed by the Wind Science and Engineering Research Center (WSERC, 2006). This scale lists increasing degrees of damage (DoDs) to 28 damage indicators (DIs). DIs involved various building types as well as other items. The EF scale was adopted by the National Weather Service (NWS) in 2007. Not surprisingly, we found that tornadoes exploit...

On 29 May 2001 several supercells developed in west Texas ahead of a dryline. However, only one s... more On 29 May 2001 several supercells developed in west Texas ahead of a dryline. However, only one storm became a prolific tornado producer. Detailed radar and satellite analyses revealed the tornadic storm (herein called the Panhandle storm) interacted with surface boundaries produced by earlier convection. This storm also interacted with the forward flank downdraft of another supercell just to the southeast (herein called the Conway storm). The authors believe that the presence of surface boundaries and interaction with a nearby storm enhanced wind and moisture convergence in the Panhandle storm aiding in tornadogenesis. This case study illustrates how mesoscale factors influence storm behavior and present difficulties in forecasting and warning.

The author conducted aerial and ground damage surveys along the Mississippi and Alabama coasts af... more The author conducted aerial and ground damage surveys along the Mississippi and Alabama coasts after Hurricane Katrina. The purpose of these surveys was to: 1) determine the height of the storm surge, 2) acquire wind velocity data, 3) determine the timing of each, and 4) assess the performance of buildings exposed to wind and water effects. Particular emphasis was placed on delineating wind and water damage. Survey work is continuing at this time and thus, the results presented herein are preliminary and subject to change. The author rode out Hurricane Katrina in Slidell, LA then conducted hundreds of site specific inspections in the months following the hurricane. Most buildings examined were wood-framed structures constructed on various foundations to include concrete slab, pier and beam, timber pilings, or masonry piers. Various building failure modes were observed. Typically, wind exploited poorly anchored or attached roofs and vinyl siding whereas wave action undermined, collap...

No sooner than a hurricane has dissipated, than another storm begins to brew about whether the da... more No sooner than a hurricane has dissipated, than another storm begins to brew about whether the damage done to buildings was caused by wind, rising water, or both. This controversy arises due to various insurance coverages. Typically, private insurance companies pay for wind damage, whereas government insurance pays for rising water damage. The task to delineate the types of building damages is left to adjusters and engineers. Occasionally, meteorologists are asked to develop a timeline with regard to the magnitudes and directions of wind and rising water for particular building locations. While meteorological studies do not take the place of detailed site inspections, they can provide a better understanding of how wind and rising water damages occurred. This paper will present certain data sources that are available to meteorologists after a hurricane and describe how to best utilize these data to establish a wind and water timeline for a particular building site. Among the most imp...

On the afternoon of May 11, 1982, several tornadoes touched down in southwestern Oklahoma. One of... more On the afternoon of May 11, 1982, several tornadoes touched down in southwestern Oklahoma. One of the tornadoes struck the east side of the city of Altus and traveled three miles in a northeasterly direction through the Altus Air Force Base, causing extensive damage. On the following day, a team of windstorm researchers from the Institute for Disaster Research at Texas Tech University went to the disaster scene. The purpose of the investigations was to define the tornado damage path and to assess the damage to structures on the base.

Weather and Forecasting, 2014

The tornado that affected Moore, Oklahoma, and the surrounding area on 20 May 2013 was an extreme... more The tornado that affected Moore, Oklahoma, and the surrounding area on 20 May 2013 was an extreme event. It traveled 23 km and damage was up to 1.7 km wide. The tornado killed 24 people, injured over 200 others, and damaged many structures. A team of surveyors from the Norman, Oklahoma, National Weather Center and two private companies performed a detailed survey (all objects/structures) of the tornado to provide better documentation than is normally done, in part to aid future studies of the event. The team began surveying tornado damage on the morning of 21 May and continued the survey process for the next several weeks. Extensive ground surveys were performed. The surveys were aided by use of high-resolution aerial and satellite imagery. The survey process utilized the enhanced Fujita (EF) scale and was facilitated by use of a National Weather Service (NWS) software package: the Damage Assessment Toolkit (DAT). The survey team defined a “well built” house that qualified for an EF...

Bulletin of the American Meteorological Society, 2014

Asphalt shingles have been utilized as a roofing material for more than one hundred years. The fi... more Asphalt shingles have been utilized as a roofing material for more than one hundred years. The first asphalt shingles were manufactured in 1901 but were not mass produced until 1911 (Snoke 1941). Asphalt shingles were originally made from cotton rags that were coated with asphalt and surfaced with slate particles (McNulty 2000). In the early 1960s, glass fiber mats were introduced as the base material for asphalt shingles which made the shingles lighter and less apt to retain detrimental moisture (Cullen 1993). Relatively inexpensive asphalt along with advancements in mat and sealant technology quickly led to asphalt shingles becoming the primary choice for steep slope roofing. In 2009, asphalt shingles comprised 57 percent of the roofing market covering 138.5 million roofing squares (The Freedonia Group 2010). (Note: A square in roofing is 100 sq. ft. or 9.3 m.) Today, there are literally billions of roofing squares covered by asphalt shingles in the United States (Noone and Blanch...

INTERFACE, 2020

Impact tests were conducted for five different shingle designs from four different shingle manufa... more Impact tests were conducted for five different shingle designs from four different shingle manufacturers. All of the shingles were advertised as having UL-2218 class ratings, including four CLASS 4-rated shingles and one CLASS-3 rated shingle. Shingles were installed on test panels and subjected to steel ball bearing drops in accordance with UL-2218, and duplicate panels were subjected to ice ball impacts in accordance with ANSI FM-4473. Upon completion of the impact testing, shingles were examined for pass/fail criteria as listed in each standard. We found that none of the five shingles adequately passed either UL-2218 or ASNI FM-4473 which calls into question the validity and quality of hail impact resistant asphalt shingles.

Hurricane Ivan struck the Alabama coast and western Florida panhandle during the late evening on ... more Hurricane Ivan struck the Alabama coast and western Florida panhandle during the late evening on September 15, 2004 and early morning of September 16, 2004 as a Category 3 storm. The eye of the storm made landfall at Gulf Shores, AL around 2 AM local time and the fragmented eyewall tracked northward up the Perdido River along the Alabama/Florida state line. The author rode out the hurricane in Warrington, FL adjacent to the Pensacola Naval Air Station. Ground and aerial damage surveys were conducted after the hurricane from Dauphin Island, AL to Fort Walton Beach, FL. This report summarizes the performance of wind and water damage to buildings and presents pertinent weather information. This information is subject to change as it was published within a few months after the event.

This was my Masters Thesis for partial fulfillment of the M.S. degree in Civil Engineering. The ... more This was my Masters Thesis for partial fulfillment of the M.S. degree in Civil Engineering. The topic involved using recently published load and resistance data along with statistical methods to place degrees of confidence in calculated failure wind speeds during damage assessments. Much of the work herein stemmed from my survey of damage to the Altus Air Force Base that was struck by a tornado on April 11, 1982.

On the afternoon of July 11, 1978, a large thunderstorm developed near the intersection of two bo... more On the afternoon of July 11, 1978, a large thunderstorm developed near the intersection of two boundaries in eastern Kansas. A gust front had been produced that morning by a large thunderstorm complex in central Missouri. This boundary had a well-defined arc shape with towering cumulus activity along the leading edge, followed by relatively clear skies. The arc cloud had several perturbations which became more numerous with time as it moved westward at 35 km/hr. In addition, a cloud boundary was located just north of a stationary front extending from a weak surface low-pressure center in western Kansas. This study shows the importance of merging boundaries in producing deep convection.

nadoes Experiment-II (VORTEX2) field project was conducted in the spring of 2009 and 2010 (Wur-ma... more nadoes Experiment-II (VORTEX2) field project was conducted in the spring of 2009 and 2010 (Wur-man et al., 2010).1 The size and scope of the Verification of the Ori-gins of Rotation in Tornadoes Experiment-II (VOR-TEX2) field project (Wurman et al., 2010) required accurate forecasts to be made in order to plan the mission of the day and set up for future missions on following days. In 2009, the steering commit-tee was responsible for making the forecasts with input from the VOC. Each member of the steering committee would take turns producing the brief-ing for the daily morning PI mission planning-meeting. VORTEX2 utilized an armada of 35-40 vehicles with a variety of mobile observ-ing equipment. More than 100 scientists, students and media traveled over much of the Great Plains during the project. Although successful forecasts were made, the amount of time required of the steering commit-tee to create forecasts distracted from other mis-sion planning duties. To remove this distract...

On 31 May 2013, an intense, multiple-vortex tornado meandered through sparsely populated areas ne... more On 31 May 2013, an intense, multiple-vortex tornado meandered through sparsely populated areas near El Reno, Oklahoma (Fig. 1). This exceptionally wide tornado had a complex path, changing rapidly in both speed and direction (Fig. 2). The tornado killed eight people, all in vehicles, including three severe storm researchers (NWS, 2013). Storm survey teams traveled to the area the next day and rated 257 DIs (damage indicators) using the EF (Enhanced Fujita) scale developed by the Wind Science and Engineering Center (WSEC, 2006). Survey teams also documented damage to 344 non-standard DIs which included 112 oil tank batteries. The maximum damage rating was determined to be EF3. Total path length was 26.2 km. In addition, the tornado was well sampled at close range by the University of Oklahoma’s Rapid-Scan, X-band, Polarimetric, mobile Doppler radar (RaXPol). The radar obtained high temporal and spatial resolution velocity data indicating instantaneous winds in excess of 130 m s-1 clo...

The author conducted aerial and ground damage surveys along the Florida and Alabama coasts after ... more The author conducted aerial and ground damage surveys along the Florida and Alabama coasts after Hurricane Ivan. The purpose of these surveys was to: 1) determine the height of the storm surge, 2) acquire wind velocity data, 3) determine the timing of each, and 4) assess the performance of buildings exposed to wind and water effects. Particular emphasis was placed on delineating wind and water damage. A similar study has just been published by FEMA (2005). The author rode out Hurricane Ivan near Pensacola, FL then conducted hundreds of site specific inspections the year following the hurricane. Most buildings examined were wood-framed structures. Remaining buildings consisted of concrete masonry as well as multi-story, steel-reinforced, concrete structures. Various building failure modes were observed. Typically, wind exploited poorly anchored or attached roofs and vinyl siding whereas wave action undermined, collapsed and destroyed buildings near the coast. Wind damage generally be...

On May 22, 2011, a large and violent tornado struck southern portions of Joplin, MO. According to... more On May 22, 2011, a large and violent tornado struck southern portions of Joplin, MO. According to the National Oceanic and Atmospheric Administration (NOAA, 2011), the tornado killed 158 people and injured more than 1000 people. The tornado was rated EF-5 on the Enhanced Fujita Scale, with maximum winds exceeding 89 ms -1 (200 mph). During the week following the tornado, the author conducted aerial and ground surveys of the damage. Surveying the damage was a challenge due to the large numbers of damaged or destroyed buildings (about 8,500 structures) as well as the rapid clean-up that was ongoing. Certain buildings were being demolished with heavy equipment within days after the tornado. Therefore, the author decided to select a sample of 14 buildings constructed with concrete masonry unit (CMU) walls. CMU buildings typically had a combination of loadbearing walls (grouted cells reinforced with steel rebar) and non load-bearing walls (no grouted cells or rebar). Walls typically fail...

A tornado outbreak occurred during the evening of 26 December 2015 across portions of North Texas... more A tornado outbreak occurred during the evening of 26 December 2015 across portions of North Texas. In all, there were 12 confirmed tornadoes in 8 counties. Unfortunately, 13 people lost their lives and there were numerous injuries as two of the strongest tornadoes struck Dallas-Fort Worth (DFW) suburbs. Most fatalities occurred in vehicles near the Interstate 30/George Bush Turnpike interchange in Garland, Texas (Fig. 1). Damage survey teams were dispatched the next day by the Fort Worth National Weather Service (FWD) to determine characteristics of the tornado paths. The survey team utilized the Enhanced Fujita (EF) scale to rate damage severity developed by the Wind Science and Engineering Research Center (WSERC, 2006). This scale lists increasing degrees of damage (DoDs) to 28 damage indicators (DIs). DIs involved various building types as well as other items. The EF scale was adopted by the National Weather Service (NWS) in 2007. Not surprisingly, we found that tornadoes exploit...

On 29 May 2001 several supercells developed in west Texas ahead of a dryline. However, only one s... more On 29 May 2001 several supercells developed in west Texas ahead of a dryline. However, only one storm became a prolific tornado producer. Detailed radar and satellite analyses revealed the tornadic storm (herein called the Panhandle storm) interacted with surface boundaries produced by earlier convection. This storm also interacted with the forward flank downdraft of another supercell just to the southeast (herein called the Conway storm). The authors believe that the presence of surface boundaries and interaction with a nearby storm enhanced wind and moisture convergence in the Panhandle storm aiding in tornadogenesis. This case study illustrates how mesoscale factors influence storm behavior and present difficulties in forecasting and warning.

The author conducted aerial and ground damage surveys along the Mississippi and Alabama coasts af... more The author conducted aerial and ground damage surveys along the Mississippi and Alabama coasts after Hurricane Katrina. The purpose of these surveys was to: 1) determine the height of the storm surge, 2) acquire wind velocity data, 3) determine the timing of each, and 4) assess the performance of buildings exposed to wind and water effects. Particular emphasis was placed on delineating wind and water damage. Survey work is continuing at this time and thus, the results presented herein are preliminary and subject to change. The author rode out Hurricane Katrina in Slidell, LA then conducted hundreds of site specific inspections in the months following the hurricane. Most buildings examined were wood-framed structures constructed on various foundations to include concrete slab, pier and beam, timber pilings, or masonry piers. Various building failure modes were observed. Typically, wind exploited poorly anchored or attached roofs and vinyl siding whereas wave action undermined, collap...

No sooner than a hurricane has dissipated, than another storm begins to brew about whether the da... more No sooner than a hurricane has dissipated, than another storm begins to brew about whether the damage done to buildings was caused by wind, rising water, or both. This controversy arises due to various insurance coverages. Typically, private insurance companies pay for wind damage, whereas government insurance pays for rising water damage. The task to delineate the types of building damages is left to adjusters and engineers. Occasionally, meteorologists are asked to develop a timeline with regard to the magnitudes and directions of wind and rising water for particular building locations. While meteorological studies do not take the place of detailed site inspections, they can provide a better understanding of how wind and rising water damages occurred. This paper will present certain data sources that are available to meteorologists after a hurricane and describe how to best utilize these data to establish a wind and water timeline for a particular building site. Among the most imp...

On the afternoon of May 11, 1982, several tornadoes touched down in southwestern Oklahoma. One of... more On the afternoon of May 11, 1982, several tornadoes touched down in southwestern Oklahoma. One of the tornadoes struck the east side of the city of Altus and traveled three miles in a northeasterly direction through the Altus Air Force Base, causing extensive damage. On the following day, a team of windstorm researchers from the Institute for Disaster Research at Texas Tech University went to the disaster scene. The purpose of the investigations was to define the tornado damage path and to assess the damage to structures on the base.

Weather and Forecasting, 2014

The tornado that affected Moore, Oklahoma, and the surrounding area on 20 May 2013 was an extreme... more The tornado that affected Moore, Oklahoma, and the surrounding area on 20 May 2013 was an extreme event. It traveled 23 km and damage was up to 1.7 km wide. The tornado killed 24 people, injured over 200 others, and damaged many structures. A team of surveyors from the Norman, Oklahoma, National Weather Center and two private companies performed a detailed survey (all objects/structures) of the tornado to provide better documentation than is normally done, in part to aid future studies of the event. The team began surveying tornado damage on the morning of 21 May and continued the survey process for the next several weeks. Extensive ground surveys were performed. The surveys were aided by use of high-resolution aerial and satellite imagery. The survey process utilized the enhanced Fujita (EF) scale and was facilitated by use of a National Weather Service (NWS) software package: the Damage Assessment Toolkit (DAT). The survey team defined a “well built” house that qualified for an EF...

Bulletin of the American Meteorological Society, 2014

Asphalt shingles have been utilized as a roofing material for more than one hundred years. The fi... more Asphalt shingles have been utilized as a roofing material for more than one hundred years. The first asphalt shingles were manufactured in 1901 but were not mass produced until 1911 (Snoke 1941). Asphalt shingles were originally made from cotton rags that were coated with asphalt and surfaced with slate particles (McNulty 2000). In the early 1960s, glass fiber mats were introduced as the base material for asphalt shingles which made the shingles lighter and less apt to retain detrimental moisture (Cullen 1993). Relatively inexpensive asphalt along with advancements in mat and sealant technology quickly led to asphalt shingles becoming the primary choice for steep slope roofing. In 2009, asphalt shingles comprised 57 percent of the roofing market covering 138.5 million roofing squares (The Freedonia Group 2010). (Note: A square in roofing is 100 sq. ft. or 9.3 m.) Today, there are literally billions of roofing squares covered by asphalt shingles in the United States (Noone and Blanch...

INTERFACE, 2020

Impact tests were conducted for five different shingle designs from four different shingle manufa... more Impact tests were conducted for five different shingle designs from four different shingle manufacturers. All of the shingles were advertised as having UL-2218 class ratings, including four CLASS 4-rated shingles and one CLASS-3 rated shingle. Shingles were installed on test panels and subjected to steel ball bearing drops in accordance with UL-2218, and duplicate panels were subjected to ice ball impacts in accordance with ANSI FM-4473. Upon completion of the impact testing, shingles were examined for pass/fail criteria as listed in each standard. We found that none of the five shingles adequately passed either UL-2218 or ASNI FM-4473 which calls into question the validity and quality of hail impact resistant asphalt shingles.

Hurricane Ivan struck the Alabama coast and western Florida panhandle during the late evening on ... more Hurricane Ivan struck the Alabama coast and western Florida panhandle during the late evening on September 15, 2004 and early morning of September 16, 2004 as a Category 3 storm. The eye of the storm made landfall at Gulf Shores, AL around 2 AM local time and the fragmented eyewall tracked northward up the Perdido River along the Alabama/Florida state line. The author rode out the hurricane in Warrington, FL adjacent to the Pensacola Naval Air Station. Ground and aerial damage surveys were conducted after the hurricane from Dauphin Island, AL to Fort Walton Beach, FL. This report summarizes the performance of wind and water damage to buildings and presents pertinent weather information. This information is subject to change as it was published within a few months after the event.

This was my Masters Thesis for partial fulfillment of the M.S. degree in Civil Engineering. The ... more This was my Masters Thesis for partial fulfillment of the M.S. degree in Civil Engineering. The topic involved using recently published load and resistance data along with statistical methods to place degrees of confidence in calculated failure wind speeds during damage assessments. Much of the work herein stemmed from my survey of damage to the Altus Air Force Base that was struck by a tornado on April 11, 1982.

On the afternoon of July 11, 1978, a large thunderstorm developed near the intersection of two bo... more On the afternoon of July 11, 1978, a large thunderstorm developed near the intersection of two boundaries in eastern Kansas. A gust front had been produced that morning by a large thunderstorm complex in central Missouri. This boundary had a well-defined arc shape with towering cumulus activity along the leading edge, followed by relatively clear skies. The arc cloud had several perturbations which became more numerous with time as it moved westward at 35 km/hr. In addition, a cloud boundary was located just north of a stationary front extending from a weak surface low-pressure center in western Kansas. This study shows the importance of merging boundaries in producing deep convection.