EF2 Tornado — Montgomery, Iowa

2024-05-21 · near Villisca, Montgomery, Iowa

Event narrative

This is a continuation of the Adams County EF-3 tornado as it came out of Page County. This tornado crossed into southern Montgomery County just east of the Montgomery-Page Street and O Avenue intersection. As the tornado continued to the northeast, it tracked through several homesteads snapping tree trunks and destroying multiple farm outbuildings. As the tornado crossed 250th Street, a radio tower was destroyed resulting in EF-2 damage. Further to the northwest at a homestead at the intersection of 240th Street and T Avenue, a home took a direct hit with the majority of its roof blown off in addition to the loss of several exterior walls on the second floor. Trees on the property were uprooted and farm outbuilding were completely destroyed and swept away. This is the strongest damage from this tornado in Montgomery County, rated EF-2 with estimated wind speeds of 130 mph. The tornado then crossed US Highway 71 three-quarters of a mile south of US Highway 34, causing damage to trees and destroying an attached garage to a residence. The walls of the garage were bolted to the foundation and had been completely swept away. The remaining house had significant roof damage, but all the walls remained. Afterwards, the tornado crossed US Highway 34 on the south side of the Hacklebarney Woods County Park. Here trees were snapped, small outbuildings were destroyed and a camping trailer was rolled on its side. The tornado then continued northeast, causing damage to outbuildings and snapping tree trunks as it crossed Vine Avenue. The tornado then crossed into Adams County (see Des Moines National Weather Service StormData) approximately two-thirds of a mile north of 210th Street.

Wider weather episode

Troughing over the western CONUS brought southwesterly flow aloft over the central and northern Plains for the duration of this event. In the couple of days leading up to May 21st, the upper-level flow pattern amplified as a trough deepened over the northern Rockies. This trough then ejected out into the central Plains on the 21st. At the surface, a stationary front developed and stretched across central Nebraska and southern Iowa by the evening of the 19th. Elevated convection that morning north of the developing surface boundary resulted in isolated instances of severe hail and wind across southeast Nebraska. Additional scattered strong to severe thunderstorms developed along this frontal boundary as it slowly lifted north, with a 64 miles per hour wind gust measured in Lancaster County and golf ball sized hail falling in Clarinda Iowa.

A weak low-pressure system developed the morning of the 20th in response to a shortwave rounding the base of the main trough out west, resulting in a cold front that pushed southeast across South Dakota and central Nebraska that afternoon. This front, however, stalled out across eastern Nebraska and western Iowa that evening, remaining draped across the region that night and into the morning of the 21st. Numerous rounds of strong and severe thunderstorms that night brought widespread severe weather and flash flooding, primarily across east-central Nebraska and southwest Iowa, though some elevated supercells in northeast Nebraska brought small hail to the area. After 10 UTC, an intense line of severe thunderstorms moved across eastern Nebraska and western Iowa bringing wind gusts ranging from 60 to 95 miles per hour, in addition to several spin-up tornadoes.

As the primary upper level disturbance ejected out over the Great Plains, intense surface cyclogenesis was noted over eastern Nebraska. This resulted in the frontal boundary that had been draped across eastern Nebraska and western Iowa that night prior to be forced northward. By 18 UTC, a strong cold front pushed through southeast Nebraska and into Iowa that afternoon. Scattered supercell thunderstorms developed along this cold front and moved across southeast Nebraska and western Iowa. These supercells became tornadic after crossing the Missouri River into Iowa, with several long-track significant tornadoes being confirmed across the state. In the OAX CWA, the strongest tornado damage confirmed was that consistent of an EF-2 in Montgomery County. This tornado continued into the DMX CWA where it caused EF-3 damage. Another tornado developed in Page County shortly before 3 PM that afternoon. This tornado went on to produce EF-4 damage in the DMX CWA. All in all, over this three-day event, 10 tornadoes were confirmed across the OAX CWA.

View location on OpenStreetMap → (40.9010, -95.0980)

Source: NOAA Storm Events Database, event_id 1188213. Narrative written by the NWS forecast office that issued the report.