Lack of Cold

Things are about to change, but the absence of cold in much of Alaska has been a pronounced anomaly for weeks - recall that Fairbanks tied its record for latest first freeze.  The coldest temperature so far at the Fairbanks airport is only 26°F, which is a record for highest minimum temperature up to this date in the autumn.

The loss of early cold in recent decades is striking.  Prior to about 2000, it wasn't uncommon at all to see temperatures drop into the single digits Fahrenheit by this date, but that's only happened once in the past decade.

Anchorage is yet to see its first freeze at the airport, only the second time that has happened since 1952.  The year 2000 also seems to mark the point at which more severe cold stopped occuring by mid-October in Anchorage.

For completeness, here's the chart for Juneau.  The last three years failed to see a freeze by this date, but not this year.

The statewide temperature index shows the sustained anomalous warmth of the past 10 days or so.

This is of course linked to the mid-level circulation pattern, involving a strong ridge centered to the south of Alaska and a strong trough over Kamchatka and the western Aleutians.  Warm southwesterly winds have prevailed between the two features, and this pronounced southerly flow is what transported ex-Typhoon Halong up to western Alaska.  The temperature contrast between the trough and the ridge also played into the re-intensification of Halong as it interacted with the mid-latitude jet stream.