Tuesday, February 13, 2024

January Climate Data

Taking a look back at January now that all the usual climate data is available, it was a month with a lot of variability, both in space and time.  Broadly speaking, the first half was mild and the second half was cold for the state as a whole, but as usual that mostly reflects the large mainland area, not peripheral regions like the southeast panhandle.  Here's the UAF statewide temperature index since November 1; despite the very unusual cold in the last 10 days of January, the average index value since November 1 is still positive (warmer than normal).

There was also a major temperature gradient between interior Alaska versus western Alaska and the North Slope:

The epicenter of cold was in the Porcupine River drainage of the northeast, with the region around Old Crow in the Yukon being particularly cold.  Old Crow itself reported -50°F or lower on 9 days and reached -61°F on the 26th; it was the coldest calendar month since 2009.  In contrast, Utqiaġvik had its 8th warmest January on record.

Precipitation was highly variable too:

The contrast between a wet northern Panhandle (e.g. record snows in Juneau) and dry southern Panhandle was significant.  There was also major variability on a scale too small to be picked up by the ERA5 data: Rick Thoman notes that Anchorage airport actually had its 10th wettest January since 1954, and yet every other site in the region had below-normal precipitation.  Here's Rick's monthly summary:

Wind was well above normal for nearly all of western and northern Alaska.  It's a bit surprising to see above-normal wind with unusual cold for the northeastern interior; I would expect a cold January to be relatively calm (i.e. stronger inversions).

Here's the complex monthly-mean pressure pattern that gave rise to the major climate anomalies: low pressure over Chukotka drew warm air up over the Bering Sea and western Alaska, but high pressure centered over northwestern Canada allowed cold air to dominate at the surface for most of the Alaskan interior.

Looking more broadly across the Arctic, January was a mixed bag there too: much warmer than normal in Canada (but not breaking monthly records), but colder than normal in northern Scandinavia.


  1. Looking ahead, here's El Nino's forecast demise:


    1. Yes, it looks like it will end rather quickly in the coming months, although the "spring predictability barrier" is always a challenge at this time of year.