Flood — Juneau Borough, Alaska

2017-10-27 to 2017-10-28 · near Douglas, Juneau Borough, Alaska

Event narrative

As moderate rain fell through the day on the 26th, Jordan Creek began to slowly rise from about one inch of rainfall in 12 hours. The creek's rate of rise started to sharpen overnight on the 26th as the snow pack in the headwaters became primed to produce more runoff to go along with the runoff from the rainfall. Jordan Creek went above minor flood stage in the early morning hours of the 27th as the rain increased to be heavy. Within 3 hours around 9 am AKDT the water levels rose above the old record stage for that site of 10.07 feet and above moderate flood stage of 10.50 feet. Jordan Creek crested at 10.97 feet, a new record, in the afternoon of the 27th and began to recede through the early evening as the rain rates began to tapper off.

There was significant flooding in the Jordan Creek area with multiple home's and business's' flooded, with some water in their crawl space and/or homes . Roads around the area were flooded but still passable. Parking lots were also flooded with some owners moving their car but some did not and were flooded with a few feet of water. Estimated flood damage costs were around 100k.

The heavy rain also produced a debris flow along the Gold Creek flume and cause damage which cost about 80k to fix.

Wider weather episode

A moderately strong atmospheric river of sub-tropical moisture moved out of the North Pacific through October 26th and over Southeast Alaska on the 27th. Leading up to the warm front drifting over the region, the northern half of the area received snow and there was about average snow pack for this time of year in the upper elevations.

Rain from the warm front moved over the area in the morning of the 26th and it became heavy at times by the 27th. Gauges in the area reported 3 to 5 inches of rain before the rain tapper off in the late afternoon of the 27th. Jordan Creek started a slow rise from this rain overnight on the 26th. Freezing levels rose above 4000 feet early on the 27th and the snow pack across Thunder Mountain, in the headwaters of Jordan Creek, became primed and significant amount of snow melt flowed into the Jordan Creek system. The water levels started a quick rise through the 27th and went above moderate flood stage by mid-morning of 27th and did not go below minor flood stage until early morning hours of the 28th.

View location on OpenStreetMap → (58.3581, -134.5737)

Source: NOAA Storm Events Database, event_id 725366. Narrative written by the NWS forecast office that issued the report.