Probably not a surprise, but we are just now entering the wettest part of the year here in western Oregon and Washington. The new 1981-2010 averages (30 year averages) show that November has once again claimed the trophy for Portland’s wettest month of the year. Of course December isn’t far behind. Then it just gradually trails off through late winter and spring. Interesting that the wettest days of each year (on average) are from Thanksgiving through the first week of December. Then it’s on to the dry season right? Not quite.
So how wet does it look? Actually I don’t see a ton of rain over the next 7-10 days. Models haven’t been doing too well on the details weatherwise beyond Sunday or Monday. For example, the 12z GFS had a relatively progressive flow into the Pacific Northwest, while the newer 00z run has far more digging of energy well out into the Pacific, leaving part of next week dry, and not big soakings anytime in the next 7 days.
The setup for the next 3 days is interesting with a surface low moving onto the central Oregon coast Saturday, then sitting somewhere between Astoria and Santiam Pass for the following 24-30 hours. This gives an easterly flow through the Gorge, upslope easterly flow into north-central and central Oregon, and the possibility for low snow levels on the east slopes of the Oregon Cascades…maybe down to or a little below 2,000′. Not a ton of moisture to work with, but something to keep an eye on later Saturday night and Sunday A.M.
The big snow this weekend will be down in the south Cascades. Our RPM is showing 10-20″ south of Willamette Pass as moisture swings inland around that surface low.
Speaking of the RPM, I’ve finally made a text output product (above) on our new graphics system that works correctly. You can see 00z and 12z text output for PDX on my weather page here: http://www.cascadeaccess.com/~mnelsen/markswxlinks.html
It’s on a pulldown menu in the MODEL DATA section.
Chief Meteorologist Mark Nelsen