Flood — Taiya Inlet, Alaska

2015-09-29 to 2015-09-30 · near Skagway, Taiya Inlet, Alaska

Event narrative

There was constant rain in the headwaters of the Taiya River basin from September 27-30. The water levels began to rise on the 28th from the first stalled warm front and continue on a stead climb through the 29th from about three to four inches in 48 hours. The more significant cold front with a lot more upper level energy and orographic lifting produced about one to one and a half inch of rain in 12 hours. That amount of rain in the headwaters with already saturated soils produced large and fast rises on the Taiya River. The runoff pushed the water level over minor flood stage in the early evening hours then over moderate flood stage overnight into early morning of September 30. Once the rain rates associated with the cold front diminished the river levels receded back below flood stage by mid morning on the 30th. The Chilkoot trail was flooded with significant amount of water over the trail with thigh deep in places along the lower portions of the trail near the river.

Wider weather episode

A series of weather fronts moved over the Southeast Alaska starting late on September 27th with the last one moving over the area early on the 30th. A strong upper trough of low pressure moved out of the Northern Bering and dug into the Northwestern Gulf of Alaska on the 27th and 28th. This tipped over the upper level ridge over the Gulf of Alaska and increased the onshore flow. The trough continue to deepen through the 29th and 30th before lifting into Canada. As the trough strengthened and dug into the North Pacific it tapped into some sub-tropical moisture and lifted it into the Gulf of Alaska. There was very high precipitable water values that fed the lifting warm fronts over the northern inner channels of Southeast Alaska. The first warm front moved over the area in the afternoon of September 27th morning hours and stalled there through the evening of the 28th. Another wave along the cold front developed and very strong surface low pressure system over the Northern Gulf of Alaska pushed another warm front over the area in the early mornings of the 29th. The very strong associated cold front pushed over the area and into Canada by the early morning of the 30th. There was significant amount of rain in the headwaters of the Taiya River basin about four to five inches in thirty-six hours and produced moderate flooding conditions along the Chilkoot Trail in Klondike National Park.

View location on OpenStreetMap → (59.5014, -135.3615)

Source: NOAA Storm Events Database, event_id 602739. Narrative written by the NWS forecast office that issued the report.