F1 Tornado — Story, Iowa

2005-09-08 · near Ames, Story, Iowa

Event narrative

A tornado touched down in the central Campas Area of ISU. Eight injuries occurred, one serious enough to require hospitalization.

Wider weather episode

A nearly stationary front extended east-southeast to west-northwest across Iowa. Cooler and drier air was to the north of the front, with very warm and unstable air to the south. Dew point temperatures approached 70 to the south of the boundary during the morning hours of the 8th. A short wave tracked southeast across the area in a general northwest flow. The air mass became quite unstable in the vicinity of the boundary with lifted indices around -7 C. The shear profile was favorable with about 40 kts of shear in the lower layers. Plenty of deep moisture was available with the system with precipitable water values in the 1.5 to 1.8 inch range. Hail was somewhat limited with the storms, but not absent with freezing levels in the 12,500 to 13,000 foot range. CAPE values ahead of the storms were in the 1500 to 2000 J/kg range, with CAPE in the -10 C to -30 C layer of the atmosphere in the 400 J/kg range. Thunderstorms which began well to the northwest during the previous night tracked southeast into Iowa during the morning of the 8th. A steady flow of moisture was transported into the area with a feed at 850 mb of about 25 kts. The storms were fast moving and the area tended to bow out. Wind damage was wide spread with numerous reports of winds of 60 to 70 MPH. An intense cluster of storms moved through the central Iowa area with measured wind gusts of 83 MPH reported at both Ames and Ankeny with the gust front passage. There was one reported tornado with the system in Ames. The tornado touched down near the power plant o nthe ISU Campus. Eight people were injured by the tornado. One was injured seriously enough to be taken to hospital. Initial damage estimates were around $150,000. Many of the storms produced hail, however much of the hail was below severe limits. Reports of penny size hail were received from several locations. The largest hail came with the cluster in central Iowa. Golf ball size hail fell west of Elkhart in Polk County. The storm and high winds resulted in power outages to 8700 customers in the Des Moines area. The high winds caused a semi-tractortrailer and a camper to oberturn on INterstate 80 just west of exit 141 in Polk County. The thunderstorms also produced locally heavy rainfall. Local flooding occurred on the north side of Indianola as the storms moved through.

View location on OpenStreetMap → (41.8833, -93.8500)

Source: NOAA Storm Events Database, event_id 5472101. Narrative written by the NWS forecast office that issued the report.