Ask a Climatologist: A remarkably warm December

A creek in Anchorage started break-up in December. (Photo by Brian Brettschneider)

December has been remarkably warm across the state. Temperatures in Fairbanks have felt more like Anchorage, Anchorage more like Juneau, Juneau more like Ketchikan. You get the idea.

Brian Brettschneider, with our Ask a Climatologist segment, says the state as a whole is likely to have the warmest December on record.

Interview Transcript:

Brian: From south to north, east to west, everyone has been much above normal. And we’re talking now: the numbers are in through the first 18, 19 days of the month. So we’re talking from Utqiagvik, Barrow, down to Ketchikan and then from Nome all the way to Fairbanks and Eagle. Again, way above normal for everybody.

Annie: Have we set any records?

Brian: Many, many stations, perhaps even most stations in Alaska, are on track to have, or at least through the 19th, have had the warmest first 19 days of December. Many of those places are solidly on track to have their warmest December on record. And as a state we’re looking really good for having perhaps our warmest December on record as a statewide value.

Annie: It’s not unusual to have warm ups in Alaska. What makes this one exceptional?

Brian: It’s really the persistence. A few places that have had their warmest single day, like Juneau had their warmest high temperature, Bettles did, a couple other places did as well, like Kotzebue. Anchorage had their warmest single day if you average the high and the low and we had a run of four days in a row of 45 degrees which had never happened in any winter month. But it’s the persistence. From December 2nd onward it’s been much, much above normal across basically the entire state. And then if you look at the extended forecast, out 8, 10 or 14 days, which takes us through the end of the year, it’s really looking quite warm, way above normal.

Annie: And what’s causing this?

Brian: We talked a few weeks ago about this upper level pattern, these Rossby waves. We’ve had this wave, this upper level area of high pressure that’s been anchored along the western part of North America and we’re on the western side of that and the flow has been from the south. So it’s been this unrelenting transport of air from lower latitudes. The flip side of that has been in the central part of North America, Canada’s been below normal, the lower 48 is about to go into an extended period of below normal. But here in Alaska we just have been stuck in that sweet spot for southerly flow and warm temperatures.

Annie: And you said we’re on track for this to continue for at least another two weeks?

Brian: Yes, so specific forecasts out more than four or five days, we really start to get into broad brush strokes. But the brush strokes are for extremely warm temperatures, much above normal. What the values are is too hard to tell. But there’s really no end in sight, until you get to January, for these remarkable conditions.

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