(This story, first posted on July 13, was updated on July 14.)
In a remarkable turnabout, the prevailing weather in large parts of Alaska is forecast to switch from historically hot to much colder than normal in the matter of a couple days late this week.
Since the fall, Alaska has been unusually warm, breaking record after record. The first half of 2016 was the state’s warmest on record, by a landslide.
On Wednesday, the town of Dead Horse in the far north soared to 85 degrees, its highest temperature ever recorded, and also the hottest temperature observed in the state within 50 miles of the Arctic Ocean, according to climatologist Brian Brettschneider.
Fairbanks tied a daily record high of 88 degrees, last reached in 2009. Bethel established a new record high of 85.
The interior of Alaska is forecast to bake yet again Thursday, with forecast highs as high as the upper 80s and low 90s in spots — some 20 degrees above normal. “This has the potential to be some of the hottest weather to occur in the interior of Alaska in several years,” the National Weather Service in Fairbanks wrote Tuesday.
But this weekend, temperatures — especially in northern Alaska — are forecast to dramatically reverse course. The Weather Service explained on Tuesday: “[Models] suggest that a very cold upper-level low with an associated cold front that will be poised in the high arctic will sweep down over northern Alaska bringing in substantially cooler air by the weekend.”
The Weather Service had said Tuesday that “this could be the coldest airmass in decades to drop south into the interior of Alaska in July.” But in its updated forecast discussion posted early Thursday, it said “over successive model runs models have backed off considerably” on the intensity of the cold.
Still, temperatures will steadily fall between Friday and Sunday – starting in the far north. In Barrow, a cold rain may mix with freezing rain and/or snow at times as the cooler air seeps in.
A second, reinforcing shot of cold air is forecast to arrive in northern and interior Alaska in the early part of next week, driving temperatures up to 20 degrees below normal (highs in the 50s) — in the same locations where it had previously been 20 degrees above normal (near 90).
It’s not clear how long this cooler than normal air will stick around, and whether it’s just a hiccup or portends a shift away from the abnormally warm conditions that have prevailed since the fall.