Higher pressure in Eastern Washington was sending air racing west to meet a cold front and its ensuing lower pressure off the coast. That air squeezed through the gaps in the Cascades in the form of a gusty, east wind.
But as that air came out of the Cascades and sank down the western slopes, it warmed up and dried out.
To wit, take a look at some of these temperature readings that were seriously toyed with by the warm winds: In North Bend, where the wind gusts were as high as 50 mph, the temperature went from 37 degrees with a light north wind at 7 a.m. Wednesday, to 53 degrees and a southeast wind the next hour. The temperature gradually warmed to 59 degrees at noon, then stayed in the 57-59 degree range all the way through the night and even into early Thursday morning.
Meanwhile, in Seattle/Sea-Tac Airport, the east wind picked up at 2:53 p.m. and the temperature warmed to 56 degrees, then peaking at a record-tying 60 degrees 34 minutes later at 3:27.
The wind slackened between 7-10 p.m. and the temperature plummeted back to around 50 degrees -- then it actually warmed back up overnight into the upper 50s as the wind reenergized, reaching 58 degrees again at 1 a.m. The wind then tapered off at 4 a.m., and the temperature plunged from 56 to 45 degrees in one hour.
The east wind is also a dry wind, and the humidity also varied wildly -- going from 86% at 9 a.m. Wednesday to 18% at 5 pm., then back up to 89% at 5 a.m. Thursday, including a one hour jump from 40% to 86% between 3 and 4 a.m.
Another interesting tidbit, in the 24 hour period between noon Wednesday and noon Thursday, the wind hit every compass direction at Sea-Tac except for northwest and due west. Try flying in that mess!