Most likely you experienced a mainly sunny weekend, OR a foggy/cloudy one. It all depends on your location because we saw the first seasonal “inversion” across the region. That’s when cool overnight air stays trapped in the valleys during the very long “winter” nights, along with moisture. The combo leads to persistent fog/clouds in some valley locations both east and west of the Cascades and it happened over the weekend, especially Sunday. This is a common feature of our climate from late November through late February.
Portland only made it to 46 yesterday and parts of the valley never broke out of the gray. Meanwhile east metro areas stayed clear with just enough drier Gorge wind keeping the clouds away. The Cascades remained sunny above the inversions too. In fact Central Oregon (above 2,000′) popped into the 60s today!
A cold front is approaching tonight and that’ll bring us with the usual steady rain turning to showers. This time a much colder airmass follows, along with strong WESTERLY flow into the Cascades. That should be very efficient at dumping lots of snow up there. 6-10″ is likely, on top of the 2-6″ on the ground at the ski resorts.
Of course that isn’t enough for Thanksgiving Weekend skiing, especially with the snow level headed WAY up the rest of the week. Lots of mild weather to wrap up November…
This mild weather pattern is caused by a “flat” upper-level ridge in the atmosphere; that’s warmer than average air over the western USA. Here’s the 500mb map for Thanksgiving Day
And then again NEXT Monday, the 29th…still mild
By the way, there are strong hints from our long range models that a turn toward more typical or even colder than normal December weather might show up about two weeks from now, but that’s WAY out there…
For now, expect lots of days in the 50s over the next week with little/no weather impacts on your Thanksgiving travel. I’ve covered the Cascades…snowy tomorrow through Wednesday morning, then much better Wednesday afternoon and pretty much clear through passes Thursday. How about the Gorge? No sign of cold air, but tomorrow’s snow WILL impact the Blue Mountains between Pendleton and La Grande
Coast Range passes will be all clear through the weekend, as will I-5 both north and south of us. Sometimes we see snow at I-5’s Siskiyou Summit south of Ashland this early in the season, but nothing significant is in the works for this long weekend.
That’s it for now, enjoy the mild Thanksgiving holiday!
Chief Meteorologist Mark Nelsen