Monday, November 2, 2015

Temperature Drop

As befits the time of year, sharply colder temperatures have occurred throughout the eastern interior in the past couple of days.  Here are some of the colder observations I've noted:

-20°F  Chicken COOP  (only 2 days ahead of the normal first occurrence of this temperature)
-18°F  Mosquito Fork HADS near Chicken 19W
-17°F  Beaver RAWS
-17°F  Chisana RAWS (3318' elevation)
-16°F  Bolio RAWS near Fort Greely
-16°F  Fort Yukon RAWS
-16°F  Bettles SNOTEL
-14°F  Chalkyitsik RAWS

North Slope locations were even a little colder, with Deadhorse dropping below the -30°C mark (-22°F); the CRN site just south of Deadhorse made it to -26°F, which appears to be the lowest temperature observed in the state so far this season.

Fairbanks managed to drop to -1°F late on Saturday evening, which was not only the first sub-zero reading but the first temperature below 19°F.  After being unusually warm for most of the month, October ended up with a sub-zero temperature after all.  It was the 8th warmest October since 1930, but was much less warm than 2013 (mean temperature 31.8°F vs 36.1°F).  Snowfall in the last 3 days of the month produced an October total of 3.8", which is the 9th lowest since 1930.

The persistent warmth of October gave the perception of a much-lengthened autumn and delayed onset of winter in Fairbanks, but certain other parts of the interior experienced a more wintry scene throughout most of October.  For example, in Circle Hot Springs (elevation 860') the late September snow never melted off, and temperatures remained almost continuously below freezing after the 8th of the month.  The chart below shows the contrasting conditions between these two locations that are separated by only about 100 miles and 400' elevation.

On another note, webcam photos reveal that the Chena River froze up in the past 24 hours in Fairbanks, but the Tanana is still open at Nenana.


  1. Woke up this morning expecting to see ice floes moving on the Chena, but it did indeed freeze overnight. I wouldn't walk on it just yet, though.

    I remember last year how it seemed like forever for the river to freeze once ice started to be seen. This year it seemed almost instantaneous.

  2. Sometimes (I've not looked this year) the interface of the Tanana and Chena rivers gets clogged up with the spinning frazil ice floes. That can also happen in the lower Chena above the Tanana R junction. Shallows, a wide spot, or a slowing of the current is all it takes to jam and back up the surface ice.

    The effect of freezing downstream and water backup affecting gage level can be seen here for both the Chena River near Fairbanks and at the lower river gage site:,00060

    The Lower Chena's values show a similar rise in level preceded by a corresponding drop in air temps:

    There's a deep gravel pit off Danby to Aurora Drive that's ice free. Local ducks are enjoying their last float on that pond.


    1. Won't be long for a freeze at Nenana...the water temp is close to 0*C and the gage height and discharge are decreasing:


    2. Thanks for the informative links, Gary. Interesting to see the water backup effect.

    3. The gravel pit I mentioned is still ice free:°51'09.3%22N+147°45'24.2%22W/@64.852586,-147.7589007,504m/data=!3m2!1e3!4b1!4m2!3m1!1s0x0:0x0

      The University has done ice research there in the winter via their ALISON project: