Southeast Interior Heatwave

I was about to post a quick summary of August climate anomalies, but a more urgent imperative is to comment briefly on the remarkable heatwave of last Thursday in the southeastern interior (I overlooked it at the time).  Here's the 500mb setup at 4pm Thursday, showing a tremendous ridge over northwestern Canada:

The deep southerly flow brought extremely warm air up from the south, and eastern Alaska was actually just on the western edge of the thermal anomaly:

Here are some of the observed high temperatures, with the highest readings found in the upper Tanana River valley and the Fortymile country (click to enlarge).

Some of the RAWS measurements are no doubt a few degrees too high, as is typical in warm, sunny weather, but reliable data from established sites confirms that this was a record-breaking event.  For example:

80°F in Northway is a record for September: the previous record was 79°F in 1982.

78°F in Eagle is close to a monthly record, but 80°F was observed on the 12th in 2021.

76°F in Gulkana is a tie for the warmest on record so late in the season; it seems there was a remarkably hot spell in early September 1917 (Eagle was also very warm at the same time).  If not for that event, this would be a new monthly record.

Perhaps most remarkable of all, Chicken reached 80°F - the same location that dropped to 14°F only 5 days earlier.  This is a remarkable feat, and it's worth a bit of research to see if such a temperature rebound to summer-like warmth has ever been observed anywhere in Alaska before.  It certainly hasn't in Chicken (with data only back to 1997) - the previous warmest subsequent to a 14°F freeze was 71°F in 2012.  In Northway it once reached 72°F after dropping to 12°F (in 1987), and it may have reached 74°F in Tok after a 14°F low (in 1989).  But I'm not seeing anything close to 80°F.  Needless to say, the 80°F is also a monthly record for Chicken (previously 72°F in 2019).