# Mobile radar observation of tornadoes

Starting in the mid-1900s, mobile radar vehicles were being used for academic and military research. In the late 1900s, mobile doppler weather radars were designed and created with the goal to study atmospheric phenomena.

## History

Mobile doppler weather radars have been used on dozens of scientific and academic research projects from their invention in the late 1900s. One problems facing meteorological researchers was the fact that mesonets and other ground-based observation methods were being deployed too slow in order to accurately measure and study high-impact atmospheric phenomena. In 1993, the Electra Doppler Radar (ELDORA) system was created, consisting of a dual-beam radar mounted on top of a Lockheed P-3 Orion aircraft. The system was designed to provide high-resolution measurements of characteristics of very large storms when ground-based radar cannot. Between 1994-1995, the first Doppler on Wheels was constructed and was deployed for the first time at the end of the VORTEX1 Project. The Doppler on Wheels led to several scientific breakthroughs and theories regarding tornadoes. The Doppler on Wheels also led to the “first tornado wind maps, measurements of an axial downdraft and lofted debris, multiple vortices, winds versus damage and surface measurement intercomparisons, winds as low as 3–4 m (9.8–13.1 ft) above the ground level and low-level inflow, 3D ground-based velocity track display (GBVTD) vector wind field retrievals, rapid evolution of debris over varying land use and terrain, documentation of cyclonic/anticyclonic tornado pairs and documentation of varied and complex tornado wind field structures including multiple wind field maxima and multiple vortex mesocyclones, downward propagation of vorticity and an extensive climatology of tornado intensity and size revealing, quantitatively, that tornadoes are much more intense and larger than indicated by damage surveys.”
In 2011, Howard Bluestein, a research professor at the University of Oklahoma, led a team to develop the Rapid X-band Polarimetric Radar (RaXPol). In 2013, researchers published to the American Meteorological Society that RaXPol was created because “the need for rapidly scanning weather radars for observing fast-changing weather phenomena such as convective storms, microbursts, small-scale features in hurricanes, and the process of convective development has been well established” throughout history. This included publications by the National Center for Atmospheric Research in 1983, research by several scientists published in 2001, and published research by the U.S. federal government in 2012. The United States Department of Defense gave the University of Oklahoma over $5 million dollars (2019 USD) in the development of new mobile radars, which were set to be used by the United States Navy.
In 2023, the University of Oklahoma, along with the National Severe Storms Laboratory developed and deployed the first ever mobile phased array radar (HORUS).

## List of notable observations

Several tornadoes throughout the last few decades have been observed by various mobile radars. However, only the most notable ones are used for academic research and subsequently published. This is a list of known tornadoes which were observed by mobile radars.

### 1990–1999

| Official rating | Date | Location | Minimum peak wind speed | Maximum peak wind speed | Highest confirmed peak wind speed |
| F4 | April 26, 1991 | Ceres, Oklahoma | 268 mph (431 km/h) | 280 mph (450 km/h) | 280 mph (450 km/h) |
| A University of Oklahoma chase team headed by Howard Bluestein utilized mobile doppler weather radar to analyze the tornado. The radar measured peak winds of 120–125 m/s (270–280 mph; 430–450 km/h) between 150–190 m (490–620 ft) above the surface. At the time, this represented the strongest winds ever measured by radar, including the first measurements of F5 intensity winds. ||||||
| F2 | June 2, 1995 | Dimmitt, Texas | 95 m/s (210 mph; 340 km/h) | — | 95 m/s (210 mph; 340 km/h) |
| A Doppler on Wheels vehicle recorded a peak ground-relative wind speed of 95 m/s (210 mph; 340 km/h). Peak velocity differences (ΔV) recorded at an altitude of around 60 meters reached 139 m/s (310 mph; 500 km/h). ||||||
| F2 | June 8, 1995 | McLean, Texas | 35 m/s (78 mph; 130 km/h) | — | 35 m/s (78 mph; 130 km/h) |
| F2 | June 8, 1995 | McLean, Texas | — | — | — |
| F0 | June 8, 1995 | McLean, Texas | — | — | — |
| F4 | June 8, 1995 | McLean, Texas | — | — | 92 m/s (210 mph; 330 km/h) |
| F0 | June 8, 1995 | McLean, Texas | — | — | — |
| A cyclic supercell near McLean, Texas produced five tornadoes, all of which were observed by ELDORA aircraft. The F4 tornado was recorded to have 92 m/s (210 mph; 330 km/h) winds. ||||||
| F4 | May 30, 1998 | Spencer, South Dakota | 234 mph (377 km/h) | 264 mph (425 km/h) | 264 mph (425 km/h) |
| A Doppler on Wheels recorded winds of 264 mph (425 km/h) "well below" 50 metres (160 ft) above the ground level, "perhaps as low as 5–10 metres (16–33 ft) above the radar level". The Doppler on Wheels also recorded a confirmed five-second wind speed average of 112 m/s (250 mph; 400 km/h). ||||||
| F4 | May 3, 1999 | Mulhall, Oklahoma | 246 mph (396 km/h) | 299 mph (481 km/h) | 257 mph (414 km/h) |
| A Doppler on Wheels documented the largest-ever-observed core flow circulation with a distance of 1,600 m (5,200 ft) between peak velocities on either side of the tornado, and a roughly 7 km (4.3 mi) width of peak wind gusts exceeding 43 m/s (96 mph), making the Mulhall tornado the largest tornado ever measured quantitatively. The DOW measured a complex multi-vortex structure, with several vortices containing winds of up to 115 m/s (260 mph) rotating around the tornado. The 3D structure of the tornado has been analyzed in a 2005 article in the Journal of the Atmospheric Sciences by Wen-Chau Lee and Joshua Wurman. In 2024, it was published that the radar did measure winds of approximately 257 mph (414 km/h) approximately 30 m (98 ft) above the radar level. ||||||
| F5 | May 3, 1999 | Bridge Creek, Oklahoma | 281 mph (452 km/h) | 321 mph (517 km/h) | 321 mph (517 km/h) |
| In 2007, Joshua Wurman along with other researchers, published that a Doppler on Wheels recorded 135 m/s (300 mph; 490 km/h) approximately 32 metres (105 ft) above the radar level. In 2021, Wurman along with other researchers, revised the data using improved techniques and published that the Doppler on Wheels actually recorded 321 miles per hour (517 km/h) in the tornado. ||||||

### 2000–2009

| Official rating | Date | Location | Minimum peak wind speed | Maximum peak wind speed | Highest confirmed peak wind speed |
| F0 | April 30, 2000 | Crowell, Texas | — | — | — |
| F0 | April 30, 2000 | Crowell, Texas | — | — | — |
| F0 | April 30, 2000 | Crowell, Texas | — | — | — |
| Three F0 tornadoes were observed by Doppler on Wheels near Crowell, Texas on April 30, 2000. ||||||
| F1 | April 30, 2000 | Oklaunion, Texas | — | — | — |
| A Doppler on Wheels observed this F1 tornado. ||||||
| F2 | May 29, 2004 | Geary, Oklahoma | — | — | 181 mph (291 km/h) |
| A Doppler on Wheels recorded a peak wind gust of 81 m/s (180 mph; 290 km/h) at 6.5 m (21 ft) above the ground level. ||||||
| F1 | May 29, 2004 | Calumet, Oklahoma | — | — | — |
| A Doppler on Wheels observed an anticyclonic F1 tornado near Calumet, Oklahoma. ||||||
| F1 | May 13, 2005 | Truscott, Texas | — | — | 110 mph (180 km/h) |
| A Doppler on Wheels observed the tornado and recorded a peak wind speed of 110 mph (180 km/h). ||||||
| F3 | May 13, 2005 | Vera, Texas | — | — | 177 mph (285 km/h) |
| A Doppler on Wheels recorded a peak wind speed of 177 mph (285 km/h) about 30 m (98 ft) above the ground level. ||||||
| F0 | May 13, 2005 | Bomarton, Texas | — | — | 51 mph (82 km/h) |
| A Doppler on Wheels recorded a peak wind speed of 51 mph (82 km/h) about 20 m (66 ft) above the ground level. ||||||
| F2 | June 12, 2005 | Clairemont, Texas | 100 mph (160 km/h) | 201 mph (323 km/h) | 201 mph (323 km/h) |
| A Doppler on Wheels observed the tornado through its entire life. The radar recorded winds of 100 mph (160 km/h), 145 mph (233 km/h), and 201 mph (323 km/h) at various heights ranging from 3–50 m (9.8–164.0 ft). ||||||
| F0 | June 15, 2005 | Trego Center, Kansas | — | — | — |
| A Doppler on Wheels observed the tornado in an open field. ||||||
| EF5 | May 4, 2007 | Greensburg, Kansas | — | — | 179 mph (288 km/h) |
| An X-band mobile radar owned by the University of Massachusetts (UMass X-Pol) observed the tornado for roughly 34 minutes after its birth. Recorded winds "exceeding 80 m/s" (179 mph; 288 km/h) were noted roughly 1.5 km above the radar level. ||||||
| EF2 | June 5, 2009 | Goshen County, Wyoming | — | — | 271 mph (436 km/h) |
| A Doppler on Wheels observed the entire lifecycle of an EF2 tornado in Goshen County, Wyoming. The radar also observed a peak wind speed of 271 mph (436 km/h) at 15–20 m (49–66 ft) above the ground level. ||||||

### 2010–2019

| Official rating | Date | Location | Minimum peak wind speed | Maximum peak wind speed | Highest confirmed peak wind speed |
| EF5 | May 24, 2011 | Hinton, Oklahoma | 289 mph (465 km/h) | 296 mph (476 km/h) | 295.5 mph (475.6 km/h) |
| RaXPol recorded a wind gust of 124.8 m/s (279 mph; 449 km/h) about 200–230 feet (60–70 m) above the radar level. However, this data was later revised to be 132.1 m/s (295 mph; 476 km/h) at 72 ft (22 m) above the radar level. ||||||
| EF4 | May 18, 2013 | Rozel, Kansas | 165 mph (266 km/h) | 185 mph (298 km/h) | 185 mph (298 km/h) |
| A Doppler on Wheels recorded "near surface" winds of between 165–185 mph (266–298 km/h). ||||||
| EF2 | May 19, 2013 | Clearwater, Kansas | — | — | 155 mph (249 km/h) |
| A Doppler on Wheels recorded winds of 155 mph (249 km/h) at 70 m (230 ft) above the ground level. ||||||
| EF5 | May 20, 2013 | Moore, Oklahoma | — | — | 140 mph (230 km/h) |
| A PX-1000 transportable radar unit operated by University of Oklahoma's Advanced Radar Research Center was used to observe the path of the tornado through Moore, with researchers detailing a "loop" in the path near the Moore Medical Center as a "failed occlusion". ||||||
| EF3 | May 28, 2013 | Bennington, Kansas | — | — | 264 mph (425 km/h) |
| A Doppler on Wheels recorded winds of 264 mph (425 km/h) approximately 153 ft (47 m) above the ground level. ||||||
| EF3 | May 31, 2013 | El Reno, Oklahoma | 291 mph (468 km/h) | 336 mph (541 km/h) | 313 mph (504 km/h) |
| A Doppler on Wheels recorded winds between 257–336 mph (414–541 km/h) at or less than 100 metres (330 ft) above the radar level in a suction vortex inside the tornado. This was later revised by the Doppler on Wheels team to 291–336 mph (468–541 km/h). In 2015, Howard Bluestein, along with other researchers, reported that the radar did capture at least a moment of winds of 313 miles per hour (504 km/h). ||||||
| EF3 | May 9, 2016 | Sulphur, Oklahoma | — | — | 218 mph (351 km/h) |
| A Doppler on Wheels operated by the Center for Severe Weather Research recorded winds of 218 mph (351 km/h) at 17 m (56 ft) above the radar level. ||||||
| EF2 | May 24, 2016 | Dodge City, Kansas | — | — | 201 mph (323 km/h) |
| While a Doppler on Wheels was observing the tornado, it documented winds of 40 m/s (89 mph; 140 km/h), which increased to at least 90 m/s (200 mph; 320 km/h) over a span of 21 seconds. These winds lasted less than one minute. ||||||
| EF2 | May 20, 2019 | Mangum, Oklahoma | — | — | 122.7 mph (197.5 km/h) |
| The University of Oklahoma's RaXPol observed this tornado and recorded a maximum VROT of 106.6 kn (122.7 mph; 197.4 km/h). ||||||

### 2023

| Official rating | Date | Location | Minimum peak wind speed | Maximum peak wind speed | Highest confirmed peak wind speed |
| EF4 | March 24, 2023 | Rolling Fork, Mississippi | — | — | 152 mph (245 km/h) |
| At least two mobile radars on the PERiLS Project observed the violent EF4 tornado at a height of 600–700 m (2,000–2,300 ft) above the radar level. ||||||

### 2024

| Official rating | Date | Location | Minimum peak wind speed | Maximum peak wind speed | Highest confirmed peak wind speed |
| EF3 | April 26, 2024 | Harlan, Iowa | — | — | 224 mph (360 km/h) |
| A Doppler on Wheels recorded a wind gust of ~79 m/s (180 mph) about 258 m (846 ft) above the radar level. Peak ground level wind speed was estimated around 224 mph (360 km/h). ||||||
| EF2 | April 27, 2024 | Dexter, Kansas | — | — | — |
| EF1 | April 27, 2024 | Dexter, Kansas | — | — | — |
| A Doppler on Wheels observed an EF2 and an EF1 tornado near Dexter, Kansas. ||||||
| EF2 | May 19, 2024 | Custer City, Oklahoma | — | — | 197 mph (317 km/h) |
| A Ka-band mobile radar unit from Texas Tech University recorded a 0-second gust of 87.9 m/s. ||||||
| EF4 | May 21, 2024 | Greenfield, Iowa | 309 mph (497 km/h) | 318 mph (512 km/h) | ≥309 mph (497 km/h) |
| A Doppler on Wheels recorded winds of 263–271 mph (423–436 km/h) approximately 30–50 m (98–164 ft) above the radar level. Following calculations to more accurately determine peak wind speeds, it was published that ground-relative winds of 309–318 mph (497–512 km/h) could be observed briefly to the immediate east of the main circulation. ||||||
| EF2 | May 22, 2024 | Temple, Texas | — | — | — |
| A Doppler on Wheels observed an EF2 tornado near Temple, Texas. ||||||
| EF2 | May 23, 2024 | Duke, Oklahoma & Olustee, Oklahoma | — | — | 180 mph (290 km/h) |
| Two Doppler on Wheels scanned a large and long-lived EF2 tornado near Duke, Oklahoma. A mobile radar from Texas Tech University recorded winds of 180 mph (290 km/h) less than 20 m (22 yd) above the surface. ||||||
| EFU | May 25, 2024 | Windthorst, Texas | — | — | — |
| The University of Oklahoma’s RaXPol observed and documented a tornado near Windthorst, Texas. ||||||