The weather of the past week in mainland Alaska is a tale of a remarkable ridge of high pressure that intensified and migrated northward across the west coast and up into the Arctic. At its onset the northward surge of warm air brought very warm conditions to southern and western Alaska on Tuesday, including 71°F in Anchorage, 78°F in Talkeetna, 75°F in Bethel (tied for 2nd earliest 75°F on record), and 80°F at Sleetmute on the Kuskokwim River. The high-quality CRN site at Port Alsworth on Lake Clark reached 77°F, after a morning low temperature of 28°F; that's the largest daily temperature range outside of winter at that site since the sudden heat wave of late May 2013.
The heat extended farther north too: Nome reached 71°F on Tuesday, and as in Bethel, this was tied for second earliest on record for such warmth (72°F occurred in May 22, 2002).
Below are 500mb height charts from 3am on Monday, Tuesday, and Wednesday mornings: the ridge ballooned up into the Arctic by Wednesday, with a remarkable peak geopotential height of 5700m. This is the highest on record for the month of May over the Pacific side of the Arctic Ocean (based on ERA5 data since 1950).