Winter Storm — Upper Koyukuk Valley, Alaska

2009-01-14 to 2009-01-15 · Upper Koyukuk Valley, Alaska

Wider weather episode

A 965 mb low across the eastern Aleutians re-developed across southwest Alaska on the evening of the 14th, and lifted north to northwest Alaska on the morning of the 15th. The low brought heavy snow and freezing rain to a large portion of northern Alaska. The snow combined with high winds to produce blizzard conditions in parts of the Brooks Range.

Zone 206: There were DOT reports of near blizzard conditions at Atigun Pass along the Dalton Highway, and based on surrounding observations there was likely 6 inches or more of snow in spots along the Dalton Highway and across the higher elevations of the Brooks Range.

Zone 208: Heavy snow was observed at Noatak. The cooperative observer at Noatak observed 6.5 inches of snow from the morning of the 14th through the morning of the 15th.

Zone 209: Heavy snow was observed at Kotzebue, and likely occurred at Selawik. Seven inches of snow was observed at Kotzebue.

Zone 210: Based on the observations from the Deering and Buckland ASOS's, along with the measured snowfall in Kotzebue, it is estimated that 7 to 9 inches of snow likely accumulated.

Zone 212: Based on the observation of 7 inches of snow at Kotzebue along with the visibility restrictions on the Koyuk AWOS, it is estimated that 8 to 12 inches of snow fell in the upslope areas across the Nulato Hills. Temperatures at Unalakleet briefly climbed above freezing early on the morning of the 15th, and this may have produced areas of freezing rain along the eastern Norton Sound coast.

Zone 215: Based on the NWS observation of 8.7 inches of snow at McGrath, it is estimated that 8 to 12 inches of snow fell along the eastern slopes of the Nulato Hills. Based on the observations of near to above freezing temperatures from the Marshall and Russian Mission AWSS's, it is likely that the snow changed to freezing rain in spots, and the freezing rain likely accumulated in excess of a tenth of an inch in spots.

Zone 216: Based on the NWS observation of 8.7 inches of snow at McGrath, it is estimated that 8 to 12 inches of snow fell along the eastern slopes of the Nulato Hills. Based on the observations of above freezing temperatures at the Huslia AWOS, the Kaltag ASOS, the Galena AWSS and the Ruby AWSS, it is likely that the snow changed to freezing rain in spots, and the freezing rain likely accumulated in excess of a tenth of an inch in spots.

Zone 217: Based on the visibility reductions on the observations from Ambler AWOS there was likely 6 inches or more of snow at Ambler, and due to upslope flow, up to 1 foot of snow likely occurred on the south-facing slopes of the Brooks Range.

Zone 218: The State of Alaska DOT Camp at Chandalar reported 7 inches of new snow in the 24 hours ending 600 AKST on the 15th, and 8 additional inches at 0600 AKST on the 16th, for a storm total of 15 inches. From DOT reports it is likely there were areas of blowing and drifting snow with near zero visibilities.

Zone 219: 9.7 inches of snow was observed at Bettles. From the DOT reports it appears likely that there some blowing and drifting snow and areas of freezing rain across the higher terrain, including parts of the Dalton Highway.

Zone 225: Denali Park Co-operative Observer reported a 24-hour rainfall of 0.27 inches of rain at 0800 AKST on the 15th, then 0.02 inches at 0800 AKST on the 16th, and 0.40 inches of rain at 0800 AKST on the 17th. Estimate that rain fell mostly on the morning of the 14th by 0800 AKST, and on the 16th after 0800 AKST. A long-time Park employee said the roads were sheets of ice and that State of Alaska DOT sanding trucks were slipping backwards and sideways.

Zone 226: There were numerous reports from the DOT of ice along the Richardson Highway from MP 202 through MP 232. A weather spotter at Isabel Pass reported 8 inches of snowfall and ice accumulation from freezing rain. The freezing rain likely accumulated in excess of a tenth of an inch.

Source: NOAA Storm Events Database, event_id 142270. Narrative written by the NWS forecast office that issued the report.