Debris Flow in Craig Coastal, Alaska

It had been very wet in the area with 3 to 5 inches of rain over the 3 previous days. Heavy rain from an atmospheric river moved over western Prince of Wales Island on November 1 and persisted into the morning of November 2 with an additional 3 to 5 inches of rainfall. Rain rates ranged from 0.30 to 0.40 inches per hour. The heavy rain along with the already saturated soils increased the risk of debris flow near steep terrain. A debris flow was initiated above Port St. Nicholas road and blocked the single lane road to a subdivision with mud, trees and other debris. This blocked the road going to Craig, the main town in the area.

Deep low pressure tracked northward along the outer coast causing impacts across Southeast Alaska beginning Halloween night through November 2nd. High Winds were felt over the outer coast and heavy rain caused rivers to rise out of their banks across the southern half of Southeast Alaska with minor impacts. The ground was already saturated by moderate to heavy rain leading up to November 1 and 2 with amounts ranging from 5 to 9 inches. Multiple mudslides occurred near steep terrain after rain amount of 3.5 inches over 36 hrs along with wet antecedent soil conditions. Tight pressure gradient along the Coast Mountains resulted in strong northerly outflow winds and cold air to push southward through the northern inner channels resulting in heavy snow.