Cold in Context

Now that the cold snap is in the past, there will be lots of opportunity for post-mortem analysis when I have a chance (and when I ditch the nasty bug I'm suffering from).  For now, I just wanted to follow-up with a final number on the weekly temperature index that I used last week to show the lack of Fairbanks-Bettles severe cold in recent decades:

https://ak-wx.blogspot.com/2024/01/cold-snaps-in-el-nino.html

Here's the updated chart:

The recent steep uptrend was indeed broken, but on a 7-day time scale the coldest week was not at all unusual by historical standards.

However, the cold spell was more notable in the end for its longevity than its severity at any one time, and so there's a more significant cold anomaly on a 14-day time scale:

Here we see a most remarkable absence of 14-day cold in recent years - almost as if the climate never recovered from the record-warm winter of 2015-16 (during the last very strong El Niño!).  The lack of variability since 2016-17 is quite amazing.

But the cold snap just ended is a significant change.  Only 15 winters since 1950 had a colder 14-day period for these two climate observing sites.

Here's the 500mb height anomaly for the 13 days that had average temperature below -30°F for Fairbanks and Bettles combined.

This too is interesting, because the mid-atmosphere anomaly is right over the northern interior; and while we might expect that to be true, in fact significant cold in Fairbanks is more often associated with a trough over western Canada.  This too will be a topic for follow-up.