Flood — Upr Tanana Vly Fortymile, Alaska

2010-07-10 to 2010-07-12 · near Chicken, Upr Tanana Vly Fortymile, Alaska

Wider weather episode

An area of low pressure moved out of the Gulf of Alaska and to the Alaska-Yukon border on the 11th. As the low moved southeast and into the southern Yukon moisture wrapped around the low and produced heavy rainfall across the Fortymile County. Rainfall amounts of 3.2 inches were observed at Chicken and O'Brien Creek, which is over one quarter of the average annual rainfall in just a little over one day.

The heavy rain caused the Fortymile River at the Taylor Highway bridge to rise 22 feet and the river crested at 94.5 feet. This surpassed the previous record of 92.4 ft on May 3, 1979 and may have surpassed the all-time record observed in 1964. Unfortunately, there are no records of the peak crest in 1964. The crest observed on O'Brien Creek which is a tributary of the Fortymile River was the highest on record. Due to the areal extent and distribution of the rainfall over the region and the resulting flood damage, this suggests that the flood was likely one of the highest floods on record for the Fortymile River basin and its tributaries.

The heavy rain washed out parts of the Taylor Highway and stranded 20 to 30 people. Seven portions of the road were completely washed out for several hundred feet, and multiple mud slides took out parts of the road. A U.S Customs Agent was missing and presumed dead after searchers found his U.S. Government Vehicle in O'Brien Creek. The Alaska State Troopers stated the driver evidently failed to negotiate a corner and his vehicle went down a 200-foot embankment and ended up i the creek.

View location on OpenStreetMap → (64.0700, -141.9500)

Source: NOAA Storm Events Database, event_id 236250. Narrative written by the NWS forecast office that issued the report.