2024 Greenfield tornado
| |
| Meteorological history | |
|---|---|
| Formed | May 21, 2024, 2:57 p.m. CDT (UTC−05:00) |
| Dissipated | May 21, 2024, 3:45 pm. CDT (UTC−05:00) |
| Duration | 48 minutes |
| EF4 tornado | |
| on the Enhanced Fujita scale | |
| Highest winds |
|
| Overall effects | |
| Fatalities | 5 |
| Injuries | 35 |
| Damage | $31,800,000[1][2] |
| Areas affected | Page, Taylor, Adams, and Adair, Iowa counties. |
Part of the Tornado outbreak sequence of May 19–27, 2024 and Tornadoes of 2024 | |
On the afternoon of May 21, 2024, a violent tornado tracked across southwestern Iowa, devastating the city of Greenfield. The tornado would destroy many structures and wind turbines across its path that stretched through Page, Taylor, Adams, and Adair counties, while also causing more than $31 million in property damage, killing five people and injuring 35 more. The tornado reached peak intensity within Greenfield, with National Weather Service surveyors denoting maximum wind speeds estimated at 185 mph (298 km/h). However, estimated winds of 309–318 mph (497–512 km/h) were briefly measured inside the tornado by a Doppler on Wheels portable radar unit, one of three times that wind speeds exceeding 300 miles per hour (480 km/h) have been determined in a tornado from radar observations.
The tornado formed amidst a week-long period of elevated tornadic activity in an area expected to be strongly conducive to the development of long-tracked and fast-moving tornadoes. Over the next 48 minutes, the tornado would be observed by multiple storm chasers and research teams, who would determine the extreme wind figure from a direct radar measurement above the city of Greenfield. In addition to one fatality on a highway in Adams County, four would die in Greenfield, with the damage in the city described as "horrific", as surveyors revealed damage consistent with a violent EF4 tornado, however multiple independent analyses have come to the conclusion that the tornado may have been capable of producing EF5 or equivalent damage. The tornado was well-observed by researchers from the Flexible Array of Radars and Mesonets team, and has been an important milestone in the practical efficacy of the Warn-on-Forecast system, which may lead to increased awareness of tornado events before they occur.
Meteorological synopsis
[edit]
On May 21, a moderate risk for severe weather was issued over the states of Iowa, Missouri, Minnesota, Wisconsin, and Illinois, highlighting a regional 15% risk for significant tornadoes.[3] Early on that morning, convective storms along bow echo associated with an outflow boundary existed over western Nebraska and were expected to move eastward through the southern third of Iowa, bringing a small risk of surface-based severe weather. To the north, a roughly west-to-east band of non-severe storms existed along a composite frontal and outflow boundary. North of this boundary existed a large area of non-severe rain showers that covered an area of dew points near 60 Fahrenheit and surface temperature in the lower 60s Fahrenheit. These showers led to atmospheric stabilization that curtailed any severe risk north of the composite boundary. As the bowing segment of convection moved eastward, its severe risk was expected to lessen.[4]
Later on that morning, a large surface low-pressure trough was present over the Midwest, primarily centered over north-central Kansas, with a secondary and weaker low center near the tri-point of South Dakota, Iowa, and Minnesota, both connected by weak atmospheric troughing. A warm front extended from the southern low center to the northeast through southeastern Nebraska and over southern Iowa. A cold front over the same low center extended southeast through central Kansas into the Oklahoma panhandle. The primary surface low was expected to move quickly to the northeast, moving the warm sector bounded by the warm front further north. This airmass was expected to be increasingly conducive for severe weather as the afternoon progressed, especially in east-central to southeastern Nebraska and west-central to southwestern Iowa. Strong ascent brought by the shortwave caused likely elevated convection over the central Nebraska/Kansas border, but as storms approached the southeastern Nebraska/southwestern Iowa airmass, it was expected to transition to a more surface-based storm mode, with the primary hazards being fast-moving supercells capable of producing severe wind gusts up to 70 mph (110 km/h), large to very large hail, and tornadoes.[5]
Early in the afternoon, the southern low center had moved to southeastern Nebraska, with the low's attached warm front, now modified by outflow, expected to rapidly move northward ahead of the shortwave trough. This caused dew points in the upper 60s Fahrenheit to be present across much of Iowa. In conjunction with this, steep mid-level lapse rates and high levels of atmospheric instability hallmarked by MLCAPE levels of 2500–3500 j/kg, as well as powerful wind fields producing elongated hodographs indicative of a shift in wind speed with height were expected to be present in the region throughout the early afternoon. All of these factors would result in an environment very conducive for significant and fast-moving severe thunderstorms. The storm mode was initially expected to be discrete, with fast-moving storms that would stay ahead of the cold front. These storms were expected to quickly develop supercellular characteristics, with strong wind gusts up to 75 mph (121 km/h), very large hail up to 3 in (7.6 cm), and strong, long-lived, and long-tracked tornadoes all being possible.[6]
A particularly dangerous situation tornado watch was issued at 1:10 p.m. over much of Iowa and parts of surrounding states. All severe weather hazards were expected as the risk of "[s]everal tornadoes and a few intense tornadoes" would exist over the highlighted region that included Greenfield. The watch outlined a 90% chance of two or more tornadoes, with an 80% chance of one or more significant (EF2–EF5) tornadoes occurring in the watch area.[7]
Tornado summary
[edit]Formation through Adams County
[edit]
The tornado would first touch down at the intersection of 110th Street and Vine Avenue in rural Page County, Iowa at 2:57 p.m. Central Daylight Time (UTC–5). Across Page County, damage up to EF1 intensity occurred, restricted primarily to tree branches, while the roof of a farm outbuilding was torn off.[8] It then briefly tracked through the far northwestern tip of Taylor County, causing no damage,[8] before moving into Adams County, where trees, power poles, and farm buildings all suffered damage past the county border. The tornado intensified as it passed through rural areas to the southeast of Nodaway, before crossing U.S. Route 34 north of Brooks, where numerous videos displayed the tornado's large funnel with an area of swirling debris below.[8] The tornado then crossed Iowa Highway 148, where 41-year-old Monica Irma Zamarron was ejected from her vehicle after being caught in the tornado's circulation.[9] The tornado began producing more EF2 damage past this point, before producing EF3 damage at the intersection of 150th Street and Notchwood Avenue, where an unanchored home lost its walls and slid off its foundation, while all nearby outbuildings were destroyed.[8] Throughout the rest of Adams County, the tornado caused damage to multiple wind turbines, many of which collapsed, while reaching a maximum width in the county of 1,300 yd (1,200 m) and exhibiting the properties of a multiple-vortex tornado.[8]
Adair County
[edit]The tornado then crossed into Adair County, still with multiple-vortex characteristics,[8] while downing a wind turbine[10] and a metal truss tower.[11] The tornado then approached Fontanelle Road, where a well-anchored home was destroyed with the debris thrown into a nearby field.[8] An outbuilding on the property was completely obliterated, although the farm equipment was mostly unmoved and not severely damaged, and trees were shredded. Northeast of there on 310th Street, a nailed down cinderblock foundation home and an outbuilding were obliterated and swept away; vehicles inside the garage of the home were damaged, but not tossed, while debris from the structures and vehicles within it were left straddling along the sides of the foundation. The tornado then moved back over open terrain, inflicting damage to an outbuilding, which was rated EF1, and downing more wind turbines. Low-end EF4 damage was observed again as the tornado crossed 290th Street where another home was leveled.[12]
Crossing Jordan Avenue, the violent tornado leveled another home, overturned a vehicle, and threw the vehicle into a tree line. A nearby home was also mostly destroyed at EF3 intensity, and more trees were snapped, including some that had partial debarking. The tornado then moved through another wind farm, collapsing additional wind turbines. As the tornado approached Greenfield from the southwest, it inflicted EF1 roof damage to a home, destroyed an outbuilding, tossed vehicles at EF2 intensity, destroyed two homes at EF3 intensity with the first one being leveled, and inflicted EF1 roof damage to another home. Right before entering Greenfield, the tornado passed over Nodaway Park Ponds and destroyed two outbuildings and inflicted severe roof damage to a home at EF2 intensity.[12]
Greenfield and dissipation
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The tornado then turned east-northeastward, entered the southwest part of Greenfield, and became violent again reaching its peak intensity of mid-range EF4 as it entered the town. Dozens of homes were leveled with some homes being partially swept away, and mobile homes and outbuildings were obliterated. The most intense damage occurred along SE 2nd Street, where a well-built home was obliterated and swept away; however, other homes that were leveled nearby were not completely swept away although debris was scattered throughout the area. The estimated wind speed at this location was 185 mph (298 km/h) as a result. Many other homes suffered extensive roof and exterior wall damage, and many large trees were snapped and stubbed, including some that landed on and contributed to houses being leveled. The tornado then briefly weakened but remained at an intense high-end EF3 strength on the southeast side of town, continuing to heavily damage homes, including some that were leveled or shifted off their foundations, obliterating mobile homes, and snap large trees. The tornado then became violent again, reaching low-end EF4 intensity on the eastern side of town near the intersection of Iowa 92 and Iowa 25. More homes were leveled, shifted off their foundations, or suffered severe roof and exterior wall damage. It also heavily damaged or destroyed more outbuildings and stubbed additional trees. All throughout the town, vehicles were destroyed and wooden power poles were snapped as well.[12][13] Four elderly people were killed and 35 other people were injured in the town.[14][15][13] The Adair County hospital suffered significant damage with lab and testing equipment being destroyed and hallways flooded. Catherine Hillestad, CEO of the hospital, stated "Had that tornado been any closer to our hospital or hit us directly, this entire building would be gone", referring to the fact that the hospital was very close to the tornado's worst damage path.[16] The tornado was rated as a mid-range EF4 with wind speeds estimated at 185 mph (298 km/h), reaching a peak width of 1,300 yards (1,200 m) along an 42.38-mile (68.20 km) path, remaining on the ground for 48 minutes. Five fatalities occurred, along with 35 injuries.[8]
Observation and research
[edit]Storm chasers and DOW observation
[edit]
Storm chaser Reed Timmer captured close-range drone footage of the tornado destroying multiple windmills over rural Iowa.[17] Chicago & Midwest Storm Chasers released a video of an aerial drone survey of Greenfield.[18]
A research team headed by Joshua Wurman and Karen Kosiba of the Flexible Array of Radars and Mesonets research team observed the Greenfield tornado with a myriad of observational instruments. While one crew went to deploy a pod of observational instruments in the direct path of the tornado for data collection, another, operating with a Doppler on Wheels (DOW) portable radar unit arrived in Greenfield at 3:30 p.m. and stationed themselves roughly 300 yd (270 m) away from the ultimate path of the tornado around 1 mile east of the center of the community. As the tornado struck Greenfield, the DOW unit experienced wind gusts of 80 mph (130 km/h) at their point of observation,[19] while a weaker tornado would form directly overhead the DOW vehicle operated by Kosiba.[20] The Greenfield tornado would narrow in width,[19] and a very brief wind gust of 263–271 mph (423–436 km/h) was measured at a height of 44 metres (144 ft), which translated to an instantaneous gust of 309–318 mph (497–512 km/h) when adjusted to a ground level estimation.[21][20] This was one of only three observations of wind speeds exceeding 300 mph (480 km/h) inside of a tornado, alongside the 1999 Bridge Creek–Moore tornado and the 2013 El Reno tornado.[22] Pieter Groenemeijer, the director of the European Severe Storms Laboratory stated in reference to the Greenfield tornado that "on the IF-scale, 250 mph measured below 60 m above ground level is IF4 on the IF-scale, 290 mph is IF5."[23]
Damage analysis
[edit]
In addition to radar data, across the street from the Adair County Memorial Hospital, the tornado ripped new concrete parking lot stop blocks from the ground, which were installed sometime after August 2023. Mechanical engineer Ethan Moriarty calculated that winds of at least 247 miles per hour (398 km/h) was needed to rip the concrete stop blocks out of the ground if they were cracked prior to being pulled up, or 283 miles per hour (455 km/h) if they were uncracked prior to being ripped out of the ground. The tornado, once nearly a mile wide at one point, had reduced in size significantly before impacting Greenfield, with the conservation of angular momentum potentially being responsible for the tornado's intensity near the end of its life. In the conclusion of his analysis, Moriarty stated that he believed the tornado was "without question a tornado capable of EF5 damage", while stating that, had the tornado been rated on a scale other than the Enhanced Fujita scale, it may have received a higher rating.[24]
Warn-on-Forecast
[edit]The National Severe Storms Laboratory used the Warn-on-Forecast system, an experimental forecasting tool using models and machine learning to predict individual storms, predicted a high probability of extremely strong surface level rotation in the vicinity of Greenfield over a full hour before the tornado began. This information was shared with National Weather Service forecasters across Iowa to assist in their warning-issuing operations. Forecasters had been discussing the implications of the Warn-on-Forecast output internally around 75 minutes before the tornado struck Greenfield. The National Oceanic and Atmospheric Administration outlines increasing meteorological lead time as aiding in their strategic goal to reduce losses of life and economic damages from severe weather events.[25]
Aftermath
[edit]
In the hours following the tornado, emergency personnel as well as storm chasers rushed into Greenfield to provide aid. Surrounding communities such as Red Oak quickly responded in Greenfield, with aid also coming from communities on the borders of Nebraska and Missouri.[26] The local St. John's Catholic Church parking lot was set up as a center for volunteers.[26] In a press conference later that day, Iowa State Patrol held a press conference in Adair County, which also included the announcements of a one-day curfew in Greenfield and the establishment of security checkpoints to get into town, with only residents being allowed to enter in the immediate aftermath.[27]
Iowa state governor Kim Reynolds toured the damage the following day, describing the views as "horrific."[28] Reynolds stated that personnel from the Federal Emergency Management Agency were in Greenfield, who would be coordinating local and state recovery personnel. Due to timely response, 50% of the town's power was restored by Thursday morning.[26] A resident of Greenfield went viral after a news clip circulated of him being distraught over losing golf clubs. In response, he received new golf clubs from Callaway and TaylorMade, and he also received an invitation to play in the John Deere Classic mini Pro-Am.[29]
By November 2024, six months following the tornado, the Greater Greenfield Community Foundation, a group intending to assist residents of the city recover, raised $1 million (2024 USD). Jeremy Cooper, the emergency manager of Adair County, stated that 51 building permits had been issued, with 34 homes under active construction.[30]
Fatalities
[edit]| Name | Age | Type of structure | Location | Additional notes | Reference |
|---|---|---|---|---|---|
| Monica Irma Zamarron | 49 | Motor vehicle | Iowa Highway 148 in Adams County | Initial reports stated that Zamarron may have been a storm chaser, but this was later rebuked by a family member. | [9][8] |
| William Williamson | 70 | Permanent home | South 5th Street in Greenfield | Williamson was rescued from his home but died of his injuries. One of Williamson's two dogs also died. | [9][8] |
| Michael Jensen | 73 | Permanent home | Southeast Jackson Street in Greenfield | [9][8] | |
| Pamela Wiggins | 77 | Permanent home | 800 block of Iowa Street in Greenfield | Pamela and Dean Wiggins were a married couple that died when the tornado struck their home north of the hospital in Greenfield. | [9][8] |
| Dean Wiggins | 78 |
See also
[edit]
- 2008 Parkersburg–New Hartford tornado, the most recent EF5 tornado in Iowa
- Tornado records
- List of F4 and EF4 tornadoes (2020–present)
- 2023 Rolling Fork–Silver City tornado, another EF4 tornado that struck Mississippi at a similar intensity the year prior
- 2024 Barnsdall–Bartlesville tornado, another EF4 tornado that struck Oklahoma two weeks prior
- Mobile radar observation of tornadoes
- Research on tornadoes in 2024
References
[edit]- ^ "Storm Events Database". National Centers for Environmental Information.
- ^ "Storm Events Database". National Centers for Environmental Information.
- ^ Edwards, Roger; Goss, Steve (May 21, 2024). "May 21, 2024 1300 UTC Day 1 Convective Outlook" (Convective Outlook). Norman, Oklahoma: Storm Prediction Center. Retrieved May 22, 2024.
- ^ Goss (May 21, 2024). "Mesoscale Discussion 867". Storm Prediction Center.
- ^ Mosier & Guyer (May 21, 2024). "Mesoscale Discussion 869". Storm Prediction Center.
- ^ Mosier & Guyer (May 21, 2024). "Mesoscale Discussion 871". Storm Prediction Center.
- ^ Guyer (May 21, 2024). "Particularly Dangerous Situation (PDS) Tornado Watch 277". Storm Prediction Center.
- ^ a b c d e f g h i j k l Survey summaries for Page, Taylor, Adams, and Adair counties:
- National Weather Service in Omaha, Nebraska (2024). Iowa Event Report: EF1 Tornado (Report). National Centers for Environmental Information. Retrieved August 19, 2024.
- National Weather Service in Des Moines, Iowa (2024). Iowa Event Report: EFU Tornado (Report). National Centers for Environmental Information. Retrieved August 19, 2024.
- National Weather Service in Des Moines, Iowa (2024). Iowa Event Report: EF3 Tornado (Report). National Centers for Environmental Information. Retrieved August 19, 2024.
- National Weather Service in Des Moines, Iowa (2024). Iowa Event Report: EF4 Tornado (Report). National Centers for Environmental Information. Retrieved August 19, 2024.
- ^ a b c d e Ages: "Authorities identify five people killed in Greenfield tornado". KWWL (TV). May 26, 2024. Retrieved February 4, 2025.
Further information: Werner, Kyle; Bacharier, Galen; Tugade, F. Amanda (May 30, 2024). "Funeral services start soon for Greenfield tornado victims". The Des Moines Register. Retrieved February 4, 2025. - ^ Information on Tornado damage point sourced from "Damage Assessment Toolkit". NOAA. 2025.
To access the DAT report, set both dates to 21 May 2024, reload, and zoom in to the affected region around 41.18 N -94.57 W. Information is then available by clicking on the highlighted marker(s). - ^ Information on Tornado damage point sourced from "Damage Assessment Toolkit". NOAA. 2025.
To access the DAT report, set both dates to 21 May 2024, reload, and zoom in to the affected region around 41.18 N -94.58 W. Information is then available by clicking on the highlighted marker(s). - ^ a b c Branches of the National Oceanic and Atmospheric Administration; National Weather Service; National Severe Storms Laboratory (2024). "Damage Assessment Toolkit". DAT. United States Department of Commerce.
- ^ a b Sutton, Joe; Tucker, Emma; Gilbert, Mary; Shackelford, Robert; Wolfe, Elizabeth (May 21, 2024). "Multiple fatalities after tornado rips through rural Iowa city, official says, as severe storms rake the Midwest". CNN. Archived from the original on May 22, 2024. Retrieved May 22, 2024.
- ^ Reyna-Rodriguez, Victoria; Kealey, Kate; Sitter, Phillip; Rood, Lee; Lathers, Addison. "Updates: Tornado, storm damage still being felt in Iowa as clean up begins". The Des Moines Register. Retrieved May 23, 2024.
- ^ "Greenfield tornado: Authorities confirm multiple fatalities in southwest Iowa". KCCI. May 22, 2024. Archived from the original on May 22, 2024. Retrieved May 22, 2024.
- ^ Bowman, Beau (November 11, 2024). "Adair County hospital fully reopens 6 months after deadly Greenfield tornado". KCCI. Retrieved February 5, 2025.
- ^ Kealey, Kate; Eller, Donelle (May 22, 2024). "Watch: Drone video shows destructive tornado topple wind turbines near Greenfield, Iowa". The Des Moines Register. Retrieved February 6, 2025.
- ^ "Drone video shows destruction, path of deadly Greenfield, Iowa tornado". KCCI. May 21, 2024. Retrieved February 6, 2025.
- ^ a b Bush, Evan; Prociv, Kathryn (June 22, 2024). "A deadly tornado and a rare feat for storm chasers". NBC News. Retrieved February 4, 2025.
- ^ a b Pflaumer, Katie (July 26, 2024). "BEST: Capturing the Worst Tornado Winds – The Front Page". Retrieved February 6, 2025.
- ^ "Flexible Array of Radars and Mesonets (FARM) statement concerning preliminary peak wind speed determinations based on Doppler On Wheels (DOW) data obtained in the Greenfield, Iowa tornado of 21 May 2024" (PDF). Champaign–Urbana metropolitan area: University of Illinois. June 23, 2024. Archived from the original (PDF) on June 24, 2024. Retrieved June 24, 2024.
- ^ Satre, Zane (June 26, 2024). "300+ mph: Greenfield, Iowa tornado had some of the strongest winds ever recorded, radar data shows". KCCI. Retrieved February 6, 2025.
- ^ Groenemeijer, Pieter (May 22, 2024). "Impressive measurement! On the IF-scale, 250 mph measured below 60 m above ground level is IF4 on the IF-scale, 290 mph is IF5" (Post on 𝕏). 𝕏 (Formerly Twitter). European Severe Storms Laboratory. Archived from the original on May 22, 2024. Retrieved May 22, 2024.
- ^ Moriarty, Ethan (October 14, 2024). "Was Greenfield an EF5 Tornado? - DAMAGE ANALYSIS: Greenfield, IA EF4" (Video). June First. Retrieved October 15, 2024 – via YouTube.
- ^ Moody, Wes (June 13, 2024). "SCIENCE IMPACT: Experimental Warn-on-Forecast System yields 75-minute lead time on violent tornado". National Severe Storms Laboratory. Retrieved February 6, 2025.
- ^ a b c Mendiola, José. "Greenfield tornado damaged, destroyed at least 153 Iowa homes in roughly one minute". The Des Moines Register. Retrieved July 5, 2024.
- ^ Dinkla, Alex (May 21, 2024). Iowa State Patrol releases statement in wake of devastating tornado (Report). Iowa State Patrol.
- ^ Opsahl, Robin (May 22, 2024). "Reynolds tours 'gut wrenching' Greenfield tornado damage, will seek federal aid". Iowa Capital Dispatch. Iowa Capital Dispatch. Retrieved July 5, 2024.
- ^ Kopatich, Kate; Donia, Joey (July 2, 2024). "Viral Greenfield, Iowa tornado victim plays in John Deere Classic mini Pro-Am". KWQC. KWQC-TV. Retrieved July 5, 2024.
- ^ Bowman, Beau (November 21, 2024). "New homes pop up in Greenfield six months after deadly tornado". KCCI. Retrieved February 6, 2024.