Flood in Juneau Borough, Alaska

Rain and rising freezing levels moved over the Juneau area through the evening hours of January 28th. The rain continued to increase in intensity and with the rising freezing level, a significant amount of runoff was going into local rivers and streams. Jordan Creek started to rise significantly in the early morning of January 29th and went over minor flood stage of 9.7 feet in the late morning. As the second low pressure system moved over the area rain rates increased again over the area, to be greater than 0.25 inches per hour at times. The amount of runoff from the overland flow into Jordan Creek rose water levels to go over the moderate flood stage of 10.5 feet at 415pm and the creek crested at 10.78 feet in the early evening of January 29th. Rain rates decreased as the cold front moved east of the area in the late evening hours and stream levels on Jordan Creek started to recede through the overnight hours. The creek was below minor flood stage by mid morning of January 30th. There was some damage to a few homes and business along the creek and roadways near Jordan Creek were impassable at times.

A strong storm force low pressure system over the North Pacific lifted north and moved into the Gulf of Alaska by the morning of January 29th. There was an associated atmospheric river along the warm side of the cold front that had a significant amount of sub-tropical moisture within it. Along with the the high anomalous moisture values, there was a very warm airmass with the atmospheric river which increased freezing levels across Southeast Alaska to more than 5000 feet. There was a deep snowpack at upper elevations and near sea level, which melted with the heavy rain to increase the amount of runoff into rivers and streams. Another low pressure system developed along the frontal boundary which stalled the front over the region to produce continued prolog heavy rain but also high winds. The combination of high winds and heavy precipitation on snow at high elevations triggered a number of avalanches near Haines.

The 2 day precipitation total across the northern half of the Southeast Alaska ranged from 2 to over 4 inches along with significant amount of snowmelt and runoff from the high freezing levels and the heavy rain melting the snowpack. The heavy rain triggered a small landslide in Haines near Lutak, another near mile 6 of Zimovia Highway in Wrangell. There was some minor overland flooding from poor drainage near the Haines airport by the afternoon of January 29th. Near the Juneau area there was a lot of minor flooding of small streams going over their banks from the rain and snow runoff through January 30th but there was moderate flooding near Jordan Creek that impacted a few homes, business and roadways.

Tree fall was was widespread across the region from this event due to the saturated ground and high wind gusts of 60 to 90 mph.