Analysis of the 2013 Moore Tornado

View of the Moore tornado moments before it impacted Briarwood Elementary School at EF5 intensity. (Video stills by David Demko and Heidi Farrar)

□ The most catastrophic tornado in recent Oklahoma history touched down in the midst of a large scale severe weather outbreak on May 20th, 2013. The tornado devastated southern sections of Moore, a large suburb to the southwest of Oklahoma City. Moore was the focus of international media following a similar F5 tornado that swept through neighborhoods only one mile to the north in May of 1999.

Aerial view of extreme tornado damage in Moore (Santa Fe Avenue is the large street at right). A damage survey later concluded that several homes on SW 147th Street (left center) were swept away in EF5 fashion (Ortega, Burgess et al., 2014). While initially reported as being in excess of two miles wide, the tornado’s primary damage path was approximately 100 to 300 yards in width. (Image by Steve Gooch)

At top left, view of the tornado as it rapidly intensified in Grady County. At bottom left, the tornado became partially rain wrapped as it crossed the Canadian River into Cleveland County. At bottom right, the tornado as it entered Moore. (Video by KWTV)

The tornado touched down at 2:55pm near the town of Bridge Creek, the same community that was nearly wiped off the map following the 1999 Moore tornado. Video of the tornado suggests it initially appeared as a large “stovepipe” before entering a period of rapid intensification, at which point it expanded and became partially shrouded in a column of rain. The swirling mass reached high-end EF4 intensity as it thundered through rural areas east of the Canadian River. Several large homes on SW 155th Street were swept completely away and grass was scoured from the ground as the tornado approached peak intensity just west of Moore. The Wallace Horse Park on Western Avenue was impacted directly by the tornado, killing all but one of the horses being held at the facility (“Oklahoma Officials…”, 2013). The bodies of several horses were recovered a quarter mile away near Sylena Way. Trees along Western Avenue were stripped of bark and branches and left pointing towards the east. The tornado reached the edge of Moore at approximately 3:15pm. Witnesses described the tornado as a “black wall” surrounded by a continuous rain of debris.

Ground scouring and empty foundations near SW 155th Street, a half mile west of Moore. The tornado was likely at EF5 intensity in this area, though building construction only permitted a high-end EF4 rating. The Wallace Horse Park was located at the intersection at top left. (Image by Steve Gooch)

Briarwood Elementary School (bottom) was impacted directly by the tornado as it entered a densely populated section of Moore. The damage to the school was deemed to be of EF5 intensity (NWS, 2013). One woman was killed just east of the school in a home on SW 147th Street. (Image by Steve Gooch)

Extreme home damage in western Moore. (Image by David McNeese)

The tornado entered Moore near the intersection of 149th and Western Avenue, where hundreds of large one and two-story brick homes were obliterated. Briarwood Elementary School was impacted directly by the tornado at EF5 intensity, resulting in the near complete destruction of the school’s classroom buildings and gym. The tornado roared eastward towards Santa Fe Avenue, where at least one fatality occurred in the destruction of a two-story home. After roaring over Penn Lane, the tornado passed directly over Plaza Towers Elementary School at probable EF5 intensity. The large, brick school was nearly leveled while more than 70 students and teachers huddled in the bathrooms. Seven students were crushed to death as the building collapsed – initial reports that the students “drowned” in a puddle or swimming pool were erroneous (Kelly, 2013). Homes just south of the school on SW 14th Street were swept completely away and grass in a nearby field was scoured from the ground. One survivor in the area said the tornado shook the ground like an earthquake and was “louder than anything he had ever heard before” (Lawrence, 2013). While the survey analysis is ongoing, aerial imagery suggests that some of the most intense damage in Moore likely occurred in the vicinity of Plaza Towers Elementary.

Satellite view of the tornado’s devastating path through Moore. The storm caused EF5 damage at Briarwood Elementary and areas to the west. Another patch of EF5 damage occurred at the northern crest of the damage path immediately west of the Moore Medical Center (Ortega, Burgess at al., 2013).

Plaza Towers Elementary School before the tornado. (Image courtesy of Google Earth)

Extreme damage to Plaza Towers Elementary School and homes to the south, which were swept from their foundations. Wind rowing and ground scouring were evident throughout the damage path in Moore. A damage survey concluded that the construction standards in this area only permitted an EF4 rating, though EF5 damage likely would have occurred had a home of “superior construction” been struck.

As the tornado continued on, it curved to the north and momentarily paused just west of Telephone Road. Four people, including a mother and her infant son, were killed after taking shelter in a walk-in freezer at a 7-Eleven convenience store on the northern margin of the damage swath (a similar tragedy occurred at a Pizza Hut in Joplin, Missouri, following an EF5 tornado in 2011). On SW 6th Street, a row of well-built homes was obliterated in EF5 fashion. Across the street, the massive tornado engulfed the Moore Medical Center. The complex was severely damaged and vehicles in the parking lot were mangled beyond recognition and piled against the building’s remaining walls. Due to extensive warning and the strong construction of the building, no fatalities occurred at the medical center. A large movie theater that had been directly in the storm’s path suffered only modest damage as the tornado’s inner core made a brief curve to the north.

The Moore Medical Center was impacted directly by the massive tornado. Dozens of cars in the adjoining parking lot were hurled against the structure’s western wing. Some vehicles nearby were damaged but largely unmoved, an indication the tornado had a violent multiple vortex structure. (Image by Steve Gooch)

At left, a tree stripped completely of bark and branches. At right, extreme damage to the well-constructed Moore Medical Center. (Images by Brett Deering)

Just east of the Moore Medical Center, the tornado crossed the I-35. More than a dozen abandoned vehicles were swept off the freeway, some of which were left in a tangled mass atop the freeway divider. The tornado began to reorganize in this area and the damage path briefly widened and became more erratic in nature. Video footage and aerial imagery indicate that a narrow core of EF4 winds developed as the tornado’s path made a slight turn to the east. Homes within a streak less than 50 yards wide were obliterated as the tornado roared through subdivisions just south of 4th street.

The remains of vehicles on the I-35. (Video still by KWTV)

In eastern Moore, the tornado narrowed and left a streak of extreme damage less than one block wide. A damage survey later concluded that three homes were swept away in EF5 fashion east of the freeway (Ortega, Burgess et al., 2014). Pictured above is damage to homes on East Moore Court. A total of 23 people were killed directly by the tornado. (Image by Steve Gooch)

The 2013 Moore tornado caused more fatalities in Cleveland County than the 1999 Bridge Creek tornado, which killed 11 in Moore and adjacent areas. Due to the severity of the damage, the 2013 tornado was upgraded to an EF5 less than 30 hours after impacting Moore.

In terms of damage intensity, the 2013 Moore tornado was comparable to the 1999 Bridge Creek tornado. Both tornadoes left multiple instances EF5 damage in the city, but the 1999 tornado reached an even greater level of intensity in rural areas to the southwest. Mobile doppler radar was not present to analyze the 2013 tornado but it is undoubtable that velocities in excess of 250mph would have been recorded during the storm’s passage through Moore.

Graphic depicting the tracks of the 1999 and 2013 tornadoes with red denoting areas of surveyed or probable EF5 damage (intensity estimates for the 2013 storm are subjective and may differ slightly from the final NWS report). The Bridge Creek tornado was nearing the end of its intensity maxima when it reached the edge of Moore but continued causing high-end EF4 damage all the way to Midwest City (out of frame at top). The 2013 tornado, by contrast, fluctuated in strength but left an intermittent trail of EF5 damage all the way across the city of Moore. The storm changed direction and narrowed significantly after crossing the I-35 but continued leaving a thin streak of extreme damage until finally weakening outside Moore.

Extreme damage following the 2013 Moore tornado near Westmoor. Due to extensive warning, few of Moore’s residences were above ground in the destroyed homes. The death toll of 23 was remarkably low considering the scope of the devastation. (Image by 1984 Studios)

The List of the Strongest Tornadoes Ever Recorded (Pre-1970): Part II

Vehicle damage is one way to ascertain the intensity of historical tornadoes, particularly since cars built pre-1960 were significantly heavier than modern light-weight vehicles. At left, extreme vehicle damage following the 1953 Beecher tornado (Image from the Flint Public Library). At center, a destroyed car after the 1956 Hudsonville tornado (Image by Thelma Bakker). At right, a truck stripped to its frame following the catastrophic Udall tornado of 1955.

□ While nowhere near definitive, objectivity is attempted through the use of damage photographs, reliable survey reports and fatality statistics. Unverified accounts, vague newspaper descriptions and damage figures are not considered. Tornadoes that occurred before 1880 and tornadoes that caused less than 10 deaths are excluded to eliminate the thousands of rural storms that failed to attract significant media attention. Little to no photographic evidence makes the inclusion of some past tornadoes unfeasible without further information.

Click to see Part I.

The list of the strongest tornadoes from 1880 to 1969:

1. Sherman, Texas – May 15, 1896

2. De Soto/Murphysboro/West Frankfurt, Illinois – March 18, 1925

3. New Richmond, Wisconsin – June 12, 1899

4. Beecher, Michigan – June 8th, 1953

5. Hudsonville, Michigan – April 3, 1956

6. Tupelo, Mississippi – April 5, 1936

7. Udall, Kansas – May 25, 1955

8. Pomeroy, Iowa – July 6, 1893

9. Woodward, Oklahoma – April 9, 1947

10. Scott County, Mississippi – March 3, 1966

11. Ruskin Heights, Missouri – May 20, 1957

12. Snyder, Oklahoma – May 10, 1905

13. Colfax, Wisconsin – June 4, 1958

14. Gans, Oklahoma – January 22, 1957

15. Winston County, Alabama – April 20, 1920

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7. Udall, Kansas – May 25, 1955

The Udall tornado caused the highest death toll in a US town with a population under 1,000. The town’s block-long business district was wrecked, whereas homes immediately to the south were swept completely away.

□ On the evening of May 25, 1955, a powerful supercell thunderstorm was edging northward near Ponca City, Oklahoma. After spawning a tornado that took 20 lives in the town of Blackwell, the storm produced another tornado that touched down near the Kansas border just before 10pm. Witnesses in the area reported that the tornado, which was made visible by near constant lightning, was approximately a quarter mile wide early in its development (NWS Storm Reports). The storm widened and strengthened as it moved northward, eventually expanding to more than half a mile in diameter. Maps from the time show the tornado traveled almost due north, but damage patterns indicate the tornado made a turn to the northeast as it roared towards the tiny town of Udall, which had only 600 residents (LIFE, 1955). The town’s population was within the boundaries of a tornado watch but a slight bureaucratic delay meant that the alert was not issued until 10:08pm. As a result, most residents who watched the 10 o’clock news were told that all advisories had been lifted (Smith, 2010). Many residents were in bed at 10:25pm, the moment the storm struck.

As the tornado reached the southwestern edge of town, it devastated the local high school and hurled vehicles from nearby houses more than a quarter mile. A massive electrical arc lit up the sky as the tornado struck a power station on 3rd Street, causing the entire town to disappear into darkness. The roar of the approaching storm gave many residents valuable time to seek shelter but the intensity of the winds below 2nd Street left nowhere safe to take cover. Rows of homes were swept completely away as the core of F5 winds passed just south of the town’s commercial strip (LIFE, 1955). The ensuing blizzard of high velocity debris killed people who attempted to run towards the few underground storm caves in town, including a couple and their two children (Raw Data Report, 1955). After leveling the town hall, the tornado crossed the railroad tracks that bisect the center of Udall and obliterated buildings in a neighborhood to the northeast. A nursing home on East Lewis Street was destroyed, leading to multiple fatalities. After exiting town, the tornado left a wide streak of scoured vegetation. (LIFE, 1955). A total of 75 people were killed in Udall, and another five lost their lives in a home south of town.

When the final people succumbed to their injuries, 13% of the town’s population was dead. There were multiple fatalities in 17 households, with up to five deaths in a single home (List of Deceased). The incredible intensity of the tornado left unusual sights across town. The damage to Udall’s public school was perhaps the most intense ever photographed. Thick, steal cross-beams arching over the school’s gym were snapped and, in some cases, blown completely away (NWS image). Near one of the classrooms, the severely denuded frame of a Ford truck was left tangled in a partially debarked tree. Areas of grass around the campus were scoured from the ground, and low-lying vegetation was stripped bare (Udall Historical Museum). Farther inside town, power poles were snapped like toothpicks several feet above the ground and a 30ft by 40ft concrete block building was swept away. The Udall event remains by far the deadliest tornado in Kansas history and one of the worst disasters to ever occur within the boundaries of tornado alley.

Vehicles across town were thrown long distances and mangled beyond recognition. At left, the tornado’s most iconic sight was the remains of a truck wrapped around a tree near the public school. A postcard from the time wrote that the (very likely deceased) driver was found a quarter mile outside town. (Images from the Udall Historical Museum)

At left, the foundation of a home that was swept completely away. Nearly every home south of 2nd Street was obliterated in F5 fashion. At right, a grade school with thick brick walls was nearly leveled to the ground. (Images from the Udall Historical Museum)

Composite aerial view of the town taken two days later after only moderate clean-up had occurred. The southern section of town (at left) was swept completely away, leaving a checkerboard of empty foundations. The rest of the community was left as a patchwork of F5 to F0 damage, with the least damage occurring in the northwest corner of town.

At left, ground scouring just east of town. At right, a field near the high school that appears to have been stripped bare (as evidenced by the post-storm tire tracks, which are a common sight in ground effected by F5 winds). The trees in the background have been completely debarked. (Right image from the Udall Historical Museum)

6. Tupelo, Mississippi – April 5, 1936

Catastrophic damage following the 1936 Tupelo tornado.

□ One of the worst tornado disasters in world history occurred in the midst of a wide-scale severe weather outbreak that brought devastating tornadoes throughout the Southeastern United States in the spring of 1936. Just after 8pm on April 5th, a massive funnel touched down approximately eight miles southwest of Tupelo, Mississippi. Little is known about the tornado’s path outside the city, but several fatalities occurred in rural areas, including one person who was killed in a vehicle swept off a road (Mississippi State Geological Survey). As the tornado raced through the outskirts of town it swept away the Burroughs home, leading to the deaths of the couple and their 11 children (New York Times, 1936).

One witness described the storm as “four funnels that merged” just west of town (The Press-Scimitar, 1936). More than a dozen large, well-constructed plantation homes were swept completely away as the tornado entered the wealthy Willis Heights neighborhood (Grazulis, 1993). Reported damage patterns indicate the tornado had a complex multiple vortex structure as some homes adjacent to the worst devastation suffered relatively modest damage (Mississippi State Geological Survey). The tornado tore through residential neighborhoods just north of the city’s business district, with most of the destruction occurring in a 300 yard wide swath centered near the intersection of Madison and Allen Street. One witness recalled that “all of a sudden, all these houses across the street went down like paper” (Edith Gurner, 2008). Residents scrambled into unusual hiding spots as the tornado approached, including one man who survived the storm after crawling into a manhole.

The tornado likely moved in excess of 55mph and took less than two minutes to reach the eastern side of Tupelo. Tens of thousands of pounds of debris were centrifuged around the core of the tornado as it crossed Gum Pond, where dozens of bodies from across town were later recovered. Many of the dead pulled from the water were black victims who likely originated from a working class neighborhood several blocks to the west. Materials from across town piled against the eastern shore of the pond as the tornado exited the area and plowed to the northeast. Heavy timbers and construction beams pierced deeply into the ground and the thick, concrete Battle of Tupelo Monument was blown apart. Additionally, fields east of town were scoured of vegetation and left covered with pulverized debris the size of woodchips (Mississippi State Geological Survey).

After the storm passed, rescue workers and the citizens of Tupelo combed the wreckage as torrential rain fell over the area. One survivor later reported that there was an eerie silence in the worst affected areas, without a single cry or moan coming from the rubble (Moore, 1992). The condition of some of the bodies made determining even the sex of the dead challenging (Mississippi State Geological Survey). Entire families were wiped out in the storm, with multiple households suffering more than five fatalities. The tornado’s final death toll is debatable due to the unknown fate of approximately 100 critically injured white patients and an unknown (but likely similar) number of injured black residents (Grazulis, 1993). The official death toll of 216 only takes into account the immediate fatalities from the storm, so later estimates were increased to 233. A final figure of 250 deaths seems appropriate, making the Tupelo event the deadliest tornado disaster in a single US town (Grazulis, 1993). The fatality rate within the main damage swath was perhaps the highest of any tornado to cause more than 100 deaths since the turn of the 20th century. While the storm was largely forgotten amidst the turmoil of the Great Depression, it remains one of the most catastrophic severe weather events to occur on American soil.

Aerial views of damage in Tupelo. At left, the devastation around Gum Pond. Possible vegetation scouring is visible atop the mound at right center. At right, looking northeast at the tornado’s path through the city.

Views of damage in Tupelo. At left, the remains of homes and a tree that was stripped bare by Gum Pond. At bottom right, only sections of baseboard remain where a home once stood.

At left, complete devastation in the eastern section of town. At right, a heavily damaged mansion that was similar to nearby residences that were reduced to their foundations. The three-story Hoffman house at 365 North Church Street was swept completely away, leading to several fatalities.

At left, the remains of the Hoffman mansion, which was swept down to its baseboards. Homes across the street suffered relatively modest damage. At right, a field that was “stripped bare” just east of town. (Mississippi State Geological Survey, 1936)

5. Hudsonville, Michigan – April 3, 1956

The Hudsonville tornado never took on the “wedge” shape typical of most F5 tornadoes and instead appeared as a large funnel, sometimes with two or more vortices visible at once. (Image by Marvin Bueker)

□ In the spring of 1956, one of the most violent tornadoes ever documented touched down far outside tornado alley in the outskirts of Grand Rapids, Michigan. Thousands of residents across the area witnessed the widely visible funnel as it turned to the north-northeast at nearly 50mph. The first instances of F5 damage occurred only five minutes after touchdown as the tornado crossed New Holland Street. Several newly built homes in the area were swept completely away, leading to the storm’s first fatality. Heavy pieces of furniture from the destroyed residences were thrown several hundred yards at high speeds, leaving long gouge marks in the ground upon impact. Aerial views of ground scouring indicate that the tornado intensified even further as it continued towards the west side of Hudsonville. The storm was well into the F5 category when it crossed the intersection of Van Buren Street and 40th Avenue. Seven homes within a 100-yard wide streak nearly vanished without a trace. The Oostendorp home was swept completely away along with the flooring and plumbing fixtures, leading to the deaths of the homeowner and his infant son (1956tornadoes). Vegetation around the home was scoured from the ground or left clinging by only a few roots, whereas neighboring homes only 60 yards to the east were left damaged but still standing.

The tornado maintained its strength as it crossed Port Sheldon Street near Elmwood Lake. Approximately fifteen homes were considered destroyed in this area. Four fatalities occurred in one home that was swept completely away. The underground basement of the home where the fatalities occurred was swept clean of furniture and personal affects. Debris from obliterated structures was whipped into long lines of wind rowing that extended more than a half mile through the surrounding fields. A car that had been driving on Port Sheldon Street was hurled several hundred feet, killing the two occupants. In total, 13 deaths were reported in the Hudsonville area.

After crossing the Grand River, the tornado swept through rural areas near the town of Standale, where four people died (Sheboygan Journal Wisconsin, 1956). The tornado would continue for another 40 miles through sparsely populated areas north of Grand Rapids. The final fatality occurred near Comstock Park, where several homes were leveled to the ground. Photographs indicate that the tornado narrowed into a long, snake-like funnel in the latter stages of its life before finally dissipating. Overall, the tornado caused 18 deaths and completely obliterated nearly 100 homes.

The remains of a home where a man and his young son were killed. Vegetation around the bare foundation was scoured from the ground and the fallen tree trunk behind the home was debarked and stripped of branches. Much of the furniture and debris from the home was found more than a quarter mile away. Amazingly, the homeowner’s wife and daughter survived the tornado, though both were critically injured. (Image by Thelma Bakker)

Extreme damage to cars near Port Sheldon Street. The mangled car at right originated from a home where four fatalities occurred. (Images by Thelma Bakker)

Aerial view of F5 damage to two homes along 40th Avenue. The tornado’s narrow path was made visible by streaks of pronounced wind rowing, an indication of extreme intensity. Similar wind rowing was photographed throughout the tornado’s damage path. All of the photographs used in this section came from 1956tornadoes flickr page, which is the single best resource for information and imagery on the Hudsonville tornado.