Storm Notes

Rick Thoman posted a comprehensive write-up of the very warm and stormy weather this month, and I'll add some more notes below.  But first it's worth noting the dramatic change since the weekend: this morning's cold was impressive across the western and northwestern interior.  The temperature dropped below -50°F at quite a number of locations generally near the Koyukuk River valley, and even Selawik in the northwest reached -49°F.  Click to enlarge:

Looking back at the weekend warmth, Fairbanks was continuously above freezing from 7am on Friday through 8pm on Sunday, i.e. 61 hours, and this is certainly the longest such stretch recorded in January - only one other day (January 15, 1981) had a daily minimum temperature above freezing.  No such days have been recorded in February, and the only ones in December occurred during the great chinook/thaw of early December 1934.  The recent warmth can't quite compare to that historic event for overall warmth (highs in the 50s back then), but there are no other events in the depths of winter that have produced the duration of thaw seen in Fairbanks over the weekend.

The historic nature of the warmth was also illustrated by 43°F at Tanana, a new record for the month of January (120 years of data!), and 49°F at Tok.  The situation at Tok was truly record-shattering, with a low of 39°F on Sunday; this means the daily mean temperature was 44°F, a full 6°F warmer than any other day in December through February, with data back to the 1950s.

The sustained flow of moisture-laden air from the southwest produced prodigious precipitation in many places.  The map below shows estimated 7-day totals in terms of liquid equivalent.  The SNOTEL instrument at McGrath reported 3.8" of precipitation, which far exceeds the record for 3-day precipitation total in winter (2.10" in 1990, data back to 1939).  Near Talkeetna, 3-day totals of 4-5" were measured at relatively low elevation, and of course much more in the mountains.

Up on the southern slopes of the Brooks Range, snowfall was very heavy - in Wiseman, for example, where snow depth is just about at a record level for the time of year.

Here's a map of reported snow depth today, courtesy of the NWS:

One more aspect that I noticed: as cold moved into northwestern Alaska on Sunday, and Fairbanks remained in a thaw, the difference in daily mean temperature between Fairbanks and Kotzebue reached +46°F, and this is also a record for the time of year.  Typically of course Fairbanks is colder in January, and in the past such a large positive temperature difference has only occurred on rare occasions in late winter through spring.

We'll be able to do more analysis on the weekend's historical context when the ERA5 data is available in a couple more days (I'm particularly interested in the moisture content/precipitable water).