Anchorage breaks annual precipitation record with combination of summer rain and recent snow

This year just officially became the wettest on record for Anchorage.

By Wednesday, the back-to-back snow storms that started a week ago provided just enough precipitation to break the old record set more than 30 years ago.

The annual precipitation record comes after a year of extremes: a drought in early summer, followed by nearly nonstop rain for months and now a series of significant December snowstorms.

As of Wednesday, Anchorage had received 27.65 inches of liquid-equivalent precipitation, just exceeding the prior annual high of 27.55 inches set in 1989.

This year’s high precipitation was driven largely by rain that began in mid-July and continued into September. The first half of the summer saw exceptionally dry conditions — this June was among the driest on record for Anchorage.

The record is part of a trend driven by warming oceans and air toward wetter weather and extreme precipitation events appearing in Alaska and other parts of the world, said Rick Thoman, a climate scientist at the University of Alaska Fairbanks.

“You’ve got more water to evaporate off the oceans and warmer atmosphere can hold it,” Thoman said. “So when all the atmospheric pieces come together to take that additional moisture and turn it into into precipitation — bingo.”

Alaska overall is becoming wetter, he said. The change is most visible on the North Slope, he said, where a significant decrease in sea ice is leaving more water exposed for longer periods of time and driving up precipitation.

Juneau broke its yearly precipitation record last week, with more than 85 inches.

“We can expect wetter years,” Thoman said. “Will every year be like this? Of course not, there’s still going to be lots of variability. ... But over the decades time scale, the trend will be for wetter years than we’ve had in the past.”

This year, the rain began in mid-July, with 4.26 inches falling for the entire month. In August, 6.8 inches of rain fell and 26 days during the month saw measurable precipitation, the highest number of days for that to have happen during any calendar month, Thoman said. In September, it rained 20 days for a total of 5.18 inches.

December has seen significant back-to-back snowstorms so far this month, with another expected to hit Wednesday night into Thursday. Driving conditions have been challenging for more than a week, as municipal and state snowplows have struggled to clear roads and sidewalks throughout Anchorage.

While these storms are unusual, they haven’t broken any major records, Thoman said. The 7-day snow total, measured near the Ted Stevens Anchorage International Airport, reached about 28 inches for both storms. Thoman said receiving that much snow or more in a week can be expected to occur only once in 20 years on average.

The month currently has 2.87 inches of liquid-equivalent precipitation, or melted snow.

With up to another foot of snow anticipated to fall this week, Thoman said it is possible Anchorage will have the snowiest December on record. The snowiest December was recorded in 1955, when 41.6 inches fell. Thoman said 32.1 inches have already been recorded in Anchorage this year. The snowiest month on record saw 52 inches of snow in February of 1996.

“It would take a lot more threading of the needle to reach that 52 inches for the highest monthly total, but the last 10 days have certainly shown us: never say never,” he said.