Power Outage in Juneau, AK

As the atmospheric river moved over the north central inner channels of Southeast Alaska it produced significant amount of precipitation from December 1-2. Heavy to moderate rainfall persisted over 36 hours with the highest amounts coming during the overnight hours going into December 2nd. By mid morning on December 1st, 2 to 3 inches of precipitation fell which is a 5 to 10 year event at the Juneau forecast office and the downtown Juneau LARC. Some of that precipitation did fall as snow, from 9 to 20 inches at elevations above 1000 feet. The snow level rose rapidly through the afternoon of December 1st to be above the mountain tops by the evening hours. This warming at elevation melted the fresh snow that fell with most gains lost by the morning of December 2nd. By the end of December 1st the Juneau airport reported a 24 hour precipitation amount of 4.93 which was a 100 year event and broke the all time daily precipitation record from 1946. Precipitation amounts for December 1st ranged from 3 to 5 inches with a number of daily precipitation records broken. Over the 2 days precipitation amounts were from 5 to 7. The Juneau airport 48hr total of 6.39 remained around the 100 year event. Other areas that did report heavy precipitation did not seem to get the intensity the airport reported. The Juneau forecast office 48hr total of 5.10 was near a 5 year event with the 24hr amount of 4.09 on December 1st was 5 to 10 year event. There was significant runoff from the intense precipitation and from the snowmelt in the mountains. Most of the small streams in the Juneau area began to rise rapidly through the morning hours of December 1st with Jordan Creek going over minor flood stage by the afternoon. As the heavy rain persisted into the evening and overnight hours going into December 2nd the soils continued to be super saturated to produce extreme runoff across the area. This produced record flooding along Jordan Creek in the early morning of December 2nd before it crested around 8am AKST at 11.20 feet for a total rise of 4.5 feet over 36 hours. Multiple homes around Jordan Creek and business in Jordan Square were flooded. Roads near the creek from Jordan Ave, Cascade St, Trout St and the main road of Glacier Highway all were significantly flooded with 1 to 3 feet of water. Due to the intense long duration heavy precipitation, additional snowmelt runoff, and high soil saturation there were multiple debris flows reported across the Juneau area near steep terrain which damaged homes, blocked a number of roads and overwhelmed culverts that damaged roads from erosion. Renninger Street, at the base of Heintzleman Ridge, accesses a city water reservoir along with a middle schools was washed out from erosion on both sides of the road. Residences along Mary Ellen Way on Vanderbilt Hill had multiple debris flows that damaged homes and deposited debris into yard that blocked drainages to divert water into homes. Multiple large debris flows occurred along the lower and upper Salmon Creek Rd and damaged the penstock that brings water from the reservoir to the ALE&P power plant and CBJ water treatment facility. This is the only water supply for DIPAC hatchery that supplies fish stock to all of Southeast Alaska. Without the water DIPAC 2021 stock will die impacting sport and commercial fisheries. A big debris flow was reported along Wire St which damages homes and blocked the Glacier Hwy. Another big debris flow was reported near the AWARE shelter along Glacier Hwy which deposited lots of mud around the shelter and surrounding homes. A home was damaged by a debris flow on Cohen Dr near Tee Harbor as the debris smashed into the side of the home removing a significant portion of the structural support. This was one of the most impactful flooding and debris flow events in recent memory and the data backups extreme impacts. The city of Juneau declared a disaster for this event.