Some of you in the lower elevations will see snow in the air by this time tomorrow night, but I think anyone below 1,500′ will have to be in the Gorge to see it.
First, the basics:
– Cold again tonight and a real chilly day tomorrow with some fog or low clouds mixed with solid incoming cloud cover by 3-4pm. We’ll be lucky to hit 40 degrees here in Portland.
– Rain arrives during the evening commute, or slightly later here in Portland. Sticking snow will be at/above 1,500′. It’s possible some of you in far western Washington county or northern Clark County could see snow in the air to lower elevations, but I don’t think it’ll stick.
– It starts as snow and stays all snow anywhere east of about Multnomah Falls in the Columbia River Gorge. A trace to 2″ (up to 2″) is possible from Multnomah Falls out to The Dalles by the middle of the night.
A couple things to note on the models this evening:
1. In the past 24 hours, models have been showing more of a split with the incoming upper-level trough. More energy heads south of us. As a result, we don’t get a surface low to the north. That means no wind tomorrow except for a continuing chilly easterly flow (not too strong) out of the Columbia Gorge. This would be a great setup for snow here in Portland; no warming south wind, but the airmass isn’t that cold over us and isn’t all that cold coming out of the Gorge either. And then there is that pesky lack of precipitation issue…see #2
2. More split = drier as well. Our RPM is showing a grand total of .13″! The WRF-GFS shows .05-.15″ for the entire metro area and the Gorge too. Okay, maybe 2″ snow maximum in the Gorge. What a waste of chilly air eh? This also doesn’t help with evaporative cooling here in the metro area tomorrow. You want steady/heavy precipitation to drag the snow level down. That’s not going to happen.
3. This is the pattern in which we sometimes get surprisingly low snow levels over western Yamhill, Washington, and Columbia counties. I don’t see the usual “signature” on models for this. Just not cold enough and not enough precipitation at the same time.
In the Cascades:
Sorry skiers, but this looks pathetic on Mt. Hood. We need some snow badly; after this event, the next decent chance is well into the first week of the Christmas Break. It appears that the biggest two weeks of the ski season (at least in numbers of people) will begin with hard-packed icy stuff off the main runs and a thin snowpack. Obviously lots of fun for the casual skiers, but no sign of fresh snow.
Chief Meteorologist Mark Nelsen