Well, well, well, sorry about that Trace-.08" this morning. Apparently it really set a person or two off didn’t it? As long as those nasty comments don’t become a regular occurrence, I’ll leave the comments open. I just love the DELETE button in this case!
So first in the short term:
We are going to be quite close to getting a "downslope" windstorm for tomorrow night and Friday. A very strong dome of Canadian high pressure slides south into the Western U.S. The air is not really all that cold, but it all comes shooting over the Cascades AND through the passes/Gorge. Peak pressure gradients across the Cascades (PDX-DLS) appear to be 10-13 millibars by early Friday morning. A 12 millibar gradient with this setup has, in the last 2 winters, produced easterly wind gusts to 60mph around Battleground/Hockinson and gusts to 45-50 mph in the hills around Portland. Often these areas get stronger wind than the Gorge since the wind is really coming right down off of the Cascade foothills. Then the offshore flow dies down pretty dramatically Friday night. So it’s going to be a 2-day windy/sunny period.
Now long term:
Models are all over the place starting on Tuesday. One common theme is retrogression of the upper-level high over us to the West. If it just moves a bit west, we stay mainly dry from Tuesday onward but cooler, but not extremely cold (12z ECMWF, 00z Canadian, 00z GFS). If it moves farther offshore, we could really get slammed with a late season arctic outbreak or snow. For now, scenario #1 seems to be more likely according to the latest evening models (no, not because I don’t want to work a long and grueling snow/ice storm!). But all is not lost even if that is the case through the middle of next week. All the models still keep a chilly pattern around for awhile.