Debris Flow and Flooding in Alaska, October 1, 2022

The water levels along the Taiya River were receding from a previous rain event that produced some minor flooding on September 29th and was near to just below bankful levels by the afternoon hours of September 30th. Moderate to heavy rain along with very warm temperatures associated with a strong atmospheric river moved over the northern inner channels of Southeast Alaska through the overnight hours going into October. The strong low level winds along with abundant sub-tropical moisture being transported over the complex terrain of the region produced very high rain amounts with 1.5 to 2 inches falling in 18 hours across the headwaters of the Taiya River basin. The combination of the heavy precipitation along with ice melt from the glaciers in the headwaters caused significant amount of runoff into the Taiya River. The Taiya River rose rapidly through the overnight hours and was above moderate flood stage of 17 feet right after midnight on October 1st. The river continue to rise at a rapid rate and crested in the mid morning at 19.38 feet. This was the third highest crest at the time. There was significant amount of flooding along the Chilkoot trail and in the town of Dyea. The National Park Service campground in Dyea was closed from flood waters inundating the entire area along with water surrounding the NPS ranger station. There was significant amount of flooding of the roads going to the Dyea historic site from culverts being overwhelmed, Dyea Road near the McDermott Road turnoff had at least 6 inches of water over the road which is just past the Taiya River bridge. There was a lot of damage to NPS infrastructure along the Chilkoot trail, Dyea campground and roads around Dyea. This was one of the most impactful flooding events that the areas has seen in almost 20 years.

Heavy rain was falling over the Chilkat Valley with 1 inch of rain falling in a 6 hour time frame. By Saturday morning on October 1st the Haines Police and Alaska DOT reported that a landslide came down during the overnight hours around 23 mile along the Haines Highway and blocked both lanes. It took all day for DOT to reopen the highway.

Moderate precipitation fell over the the Jordan Creek area in Juneau from the afternoon of September 29th to day break on September 30th. This precipitation of 1 to 1.5 inches of rain in 12 to 18 hours rose Jordan Creek to be just below bankful. Heavy rain associated with a strong atmospheric river moved into the area through the afternoon and evening hours of September 30th. Jordan Creek started to rise rapidly in response to the runoff from to the heavy rain through the night of September 30th with it going over moderate flood stage of 10.5 feet in the morning hours of October 1st from 1.5 to 2 inches in 12 hours. Jordan Creek crested at 10.98 feet in the late morning which was the the second highest crest on record from the 2 to 3 inches of rain that fell over the previous 24 hours. As the rain tapered off water levels dropped below minor flood stage by the late afternoon. There was significant flooding of roads, yards, parking lots around the Jordan Creek area and along Jordan Avenue. Some homes and business did get water into their buildings and caused some damage.