Ice Storm in Alaska, November 21 to 25, 2010

An extremely warm and moist air mass moving around a large ridge of high pressure in the north Pacific produced a prolonged period of freezing rain across much of interior Alaska on November 22-24, 2010.

Zone 216: A mix of freezing rain and snow fell across the Middle Yukon and Lower Koyukuk Valleys. Temperatures were near freezing during the event and in spots the precipitation changed back and forth between freezing rain and snow. A total of 72 hundredths of an inch of rain and melted snow was observed at the Kaltag ASOS with 29 hundredths at Ruby AWSS. A two day total of 99 hundredths of an inch was observed at the Galena Coop, which included 2.5 inches of snow on the 23rd. It is likely that some areas had between one quarter and one half of an inch of ice accumulation on untreated surfaces.

Zone 217: Based on the observations from Ambler and Shungnak it is likely that freezing rain fell in many areas south of the Kobuk River. The Selawik RAWS observed a total of 47 hundredths of an inch of precipitation and temperatures were near or a little above freezing during the event.

Zone 219: A mix of freezing rain and snow fell across The Upper Koyukuk Valley. |The precipitation fell in the form of snow at Bettles with a storm total of 3 inches. The precipitation likely started as freezing rain in the valleys south of Bettles as well as across the higher elevations along the Dalton Highway where the Gobblers Knob Snotel observered 2 to 3 tenths of an inch of precipitation, which likely fell at least in part in the form of freezing rain.

Zone 220: A mix of freezing rain and snow was observed at Central, Circle and Fort Yukon. Three day totals of just under one half inch of liquid precipitation were observed at the above locations. The Steese Highway was likely very treacherous in spots from Fox to Circle.

Zone 221: A total of 1.52 inches of rain was observed at the Nenana ASOS and 99 hundredths of an inch was observed at the Tanana ASOS. A total of 1.63 inches was observed at Lake Minchumina. Temperatures were within a few degrees of freezing during the duration of the storm and this led to a significant build up of ice on roads in areas such as Nenana and Tanana. The rain did mix with and change over to snow in spots, especially from Manley Hot Springs west. The DOT had a travel advisory out for the Elliot Highway from Wickersham Dome (MP 28) to Manley Hot Springs (MP 153) due to very slick conditions caused by freezing rain and snow.

Zone 222: A total of 95 hundredths of an inch of rain fell at the Fairbanks International Airport from 0500AKST on the 22nd through 0327AKST on November 24th. The rainfall on the 22nd of one half inch was a daily record, and the 32 hundredths of an inch of rain that fell on the 23rd was also a new daily record. This storm produced the second greatest winter rainfall of record at Fairbanks and the greatest ever observed during the month of November. Some locations in the Fairbanks area observed over an inch of rain, with 1.37 inches at Keystone Ridge on Murphy Dome and 1.16 inches at Ester. Temperatures during the event were near to or a little above freezing. In fact, there was a period of 49 consecutive hours with temperatures above freezing at the Fairbanks International Airport. This was the longest stretch of above freezing temperatures ever observed in Fairbanks during the month of November. The rain froze on colder surfaces and made the roads extremely hazardous with up to 1 inch of ice accumulation on many roads. Travel was nearly impossible in spots on the 22nd into the 23rd. The icy roads led to numerous traffic accidents with many vehicles in ditches around the area. Although the ice did accumulate in spots on trees and power lines, the buildup of ice was not significant and resulted in only sporadic power outages that in most areas lasted for no more than 12 hours. The ice storm was one of the worst in memory and shut down schools, the University of Alaska, and government offices at the Federal, State, Borough and City level. Many small businesses closed for a good part of this time. Although Fairbanks International Airport remained open there were some flight cancellations on the 22nd and 23rd.

Zone 223: Freezing rain fell at Delta Junction from 0923AKST on the 22nd until 1307AKST on the 23rd. A total of 28 hundredths of an inch of rain was observed at the Delta Junction ASOS. Fifty-nine hundreths of an inch of rain was reported at the Whitestone Farm Co-op Observation site. The freezing rain caused the school and city offices to shut down as well as Fort Greely.

Zone 224: Freezing rain fell on the night of the 23rd through early morning on the 24th. One-tenth of an inch of rain was reported by a Co-op observer and also by a Storm Spotter.

Zone 225: Freezing rain fell at Healy as well as at Denali National Park visitors center from the late morning hours on the 22nd through the early morning hours on the 24th. A total of 6 tenths of an inch of rain was observed at the Denali Visitors Center Raws with 42 hundredths of an inch observed at Healy. According to reports from DOT the Parks Highway had about an inch of ice from MP 260 north (about 10 miles north of Healy) to the Fairbanks area.

Zone 226: Freezing rain fell across parts of the Eastern Alaska Range from the early afternoon hours on the 23rd through the morning hours on the 24th. A trained weather spotter in Tok observed one tenth of an inch of ice at 5 am on the 24th. Another trained weather observer at the Robertson River Bridge reported that freezing rain began a little after midnight on the 24th and that the Alaska Highway was likely treacherous based on the amount of ice that was observed at the Robertson River Bridge.

Zone 227: A total of 2.08 inches of rain fell at McGrath and 2.86 inches was observed at Telida with 62 hundredths of an inch at Nikolai. At the start of the event temperatures were below freezing as the rain fell and produced a quarter inch of ice on untreated surfaces at McGrath. Temperatures warmed well above freezing during the afternoon hours on the 22nd and the freezing rain changed over to rain in most areas. The rain fell on top of the ice that had accumulated and continued to produce very slick surfaces.