Wednesday, August 25, 2021
Tuesday, August 17, 2021
Ten days ago I was writing about the hottest weather of the summer for interior and western Alaska, but a dramatic reversal has suddenly produced unseasonably chilly conditions instead. Widespread significant rain occurred again from the west coast to the White Mountains, and the scene has turned wintry in the Brooks Range: Atigun Pass is now reporting about 6" of snow on the ground.
Here's the FAA webcam view from Chandalar Shelf (elevation 3285') this morning:
With cloud and rain holding daytime temperatures down, Fairbanks has seen the chilliest couple of days for this early in the season since August 2002.
Interestingly the late summer of 2002 evolved quite similarly, with some distinctly warm weather in the second half of July and the beginning of August, followed by below-normal temperatures. Both years had a significant rain in Fairbanks around August 7-9, then heavy rain around the 16th.
With more than an inch of rain in Fairbanks since Sunday morning (and nearly continuous too), the summer's rainfall total is now above 5.5" and above the long-term normal, for the 8th consecutive year. I wrote about this remarkable trend in a few posts last year, for example:
For a broader look at why August tends to be wet, see the 2018 post below. The short answer is that the rapid loss of solar heating over the Arctic is already causing substantial strengthening of the jet stream, leading to more vigorous large-scale weather disturbances, and there's still a lot of moisture available in the atmosphere to produce copious rain across much of the high latitudes.
Friday, August 13, 2021
Saturday, August 7, 2021
By and large, August typically brings cooler, cloudier, and wetter weather to interior and northern Alaska as summer fades quickly, but the start of this month has seen very unusual heat across the interior and west coast. It has been the hottest spell of the summer.
Fairbanks reached 89°F at the airport on Tuesday, the highest August temperature since 2010, and the daily mean temperature was the highest on record for August, owing to a very warm daily minimum temperature of 64°F. And it wasn't just a one-day heat wave: four consecutive days reached 84°F, and this too is unprecedented in August (looking at data since 1930).
Out on the west coast, the heat was even more unusual relative to climate normals: Kotzebue reached 80°F on Wednesday, which ties the record for the month of August. Like Fairbanks, the peak daily mean temperature of 70°F set a new record for August.
Here's a map view that shows the evolving distribution of daily high temperatures: click to enlarge. (But note that the thermometer at Kivalina had a problem - it wasn't 90°F there on Tuesday.)
Here's the mid-atmosphere (500mb) circulation that brought the amazing warmth to the west on Wednesday (4pm analysis courtesy of Environment Canada):