Happy Sunday, all! Wanted to give everyone as much of a heads up as possible about this week, since many will be traveling in the days leading up to Christmas. Some kind of snow/ice event is possible in the Portland metro area, Gorge & Cascade Foothills Thur-Sat. #PDX #ORwx #WAwx 
WEDNESDAY: Starting in afternoon / evening, a cold east wind will be cranking thru the Gorge and across the Portland / Vancouver metro area. This modified arctic air will prime the region with sub-freezing air, setting the stage for a winter weather event Thursday/Friday. #PDX
THURSDAY: By Thursday morning, our temperatures will be well below freezing, somewhere between the mid teens and low 20s. Due to the strong east wind, temperatures will likely stay below freezing all day long. Colder in Gorge. Precip. will arrive from the west Thursday P.M.
Initially, precip. could fall in the form of snow. At some point, precip. will switch over to frz. rain. The timing of that won't be uniform. Just as an example: it might happen a few hrs later in Portland than McMinnville. Warmer air will be riding over top of colder air.
We all need to be prepared for roads to turn icy Thursday night. While that transition is underway near/west of the Cascades, the Gorge will be locked in to a deeper column of cold air. Should be all snow through there.
FRIDAY: Friday should start off well below freezing, with some amount of ice on surfaces. A few more waves of moisture could come through, with an off chance of some showers leading into early Saturday. If we manage to climb above freezing in metro area, it won't be by much.
(X-MAS EVE): We should start warming on Saturday. Most locations west of Cascades should be above freezing midday X-mas eve thru X-mas day. The Gorge will undergo a transition from snow to freezing rain (with any leftover precip. that passes through).
BOTTOM LINE: All of us need to be prepared for impactful winter weather later this week. High confidence in the Cascades & Gorge, and moderate confidence in the metro area and other western valley locations.
• • •
Missing some Tweet in this thread? You can try to
force a refresh
