EF3 Tornado — Monona, Iowa

2008-06-11 · near Blencoe, Monona, Iowa

Event narrative

This tornado tragically hit a boyscout camp north of Little Sioux Iowa killing 4 young scouts. The tornado initially touched down in Burt county Nebraska, crossed into Harrison county Iowa near mile marker 97 on Interstate 29, and then finally crossed into Monona county Iowa about 4 miles north of Little Sioux. In Monona county the tornado entered the Little Sioux Scout Ranch, destroying the rangers home near the entrance of the park giving it a rating of EF3. The storm then blew down trees and destroyed bunk houses at the camp. Four scouts were killed in one bunk house when a brick chimney collapsed on them. In total 48 people were injured at the camp. The tornado continued to topple trees as it tracked into Preparation Canyon State Park. Just before it entered the park a farmstead sustained damage. The tornado hit another farmstead about 2.5 miles southwest of Moorhead where trees were blown down and sheds damaged. The tornado then began to weaken and finally lifted about 2 miles southwest of Moorhead. The total path length was around 14 miles.

Wider weather episode

A very strong and unseasonably cold upper level low pressure system that was tracking across the northern plains brought a strong low level jet to the region during the early morning hours of June 11th. The warm and unstable air that worked north into the region helped spawn early morning severe thunderstorms across eastern Nebraska and southwest Iowa. Later that day as the upper level system worked into the central Dakotas, a cold front pushed across the region. This helped set off another round of thunderstorms that developed over east central Nebraska by late afternoon.

Isolated small supercell thunderstorms initially developed ahead of the cold front over eastern Nebraska, but they were quickly overtaken by a broken line of larger supercell thunderstorms, some of the heavy precipitation type, that developed along the cold front. Cell mergers and training were observed well into the evening hours as the activity quickly spread across southwest Iowa. The storms produced a total of 8 confirmed tornadoes in the Omaha/Valley warning area which covers eastern Nebraska and southwest Iowa.

View location on OpenStreetMap → (41.8641, -96.0191)

Source: NOAA Storm Events Database, event_id 98814. Narrative written by the NWS forecast office that issued the report.