Sure FEELS like snow doesn’t it?
Solid cloud cover moved in the past few hours; it’s not going anywhere until Tuesday evening. We are done with nights in the teens and single digits. Now we begin a very slow moderation of the arctic air mass over us. At the same time, northwesterly and westerly wind around 2,000′ and above is pushing moisture onto the coast and inland. Light snow has been falling north of Tillamook and up onto the Washington coastline this morning. Nothing except flurries is making it over the Coast Range…too dry. This will continue the next few hours. Thus another cold day with solid gray skies.
A weak disturbance passing overhead will squeeze flurries or freezing rain/drizzle out of the cloud layer this evening through Tuesday morning, then it’s back to dry until sometime Thursday. All the previous bullet points on last night’s post are still valid, if you didn’t read those, you should.
So for this evening’s commute, at worst I expect flurries with only a dusting with little or no effect on roads. There, I said it; now we’ll see what happens. At best it’ll just be dry. That includes the Portland metro area up to Woodland or so along I-5. I think there’s a better chance for a half-inch or less snowfall north of St. Helens on the Oregon side of the Columbia and north of Woodland (Kelso/Longview) at some point this evening.
The main chance for frozen precipitation appears to be later tonight and for Tuesday morning’s commute, with the best chance up against the Cascade foothills in Clark and Multnomah counties. This is very similar to the drizzle setup we often get where the metro area is mainly dry but it drizzles or rains lightly on the far east side of town and into the foothills. Those spots could see an inch or more.
Today is a good “radar-watching” day. Here is a link to Portland’s: http://weather.cod.edu/satrad/nexrad/index.php?type=RTX-N0Q-1-12
and the Washington Coast radar: http://weather.cod.edu/satrad/nexrad/index.php?type=LGX-N0Q-1-12
You generally need echoes above 10dbz (GREEN) to get precipitation down to ground level. That said, this evening and overnight some of the precipitation will be below the radar beam, so the radar may show nothing and it’ll be snowing at your house.
Chief Meteorologist Mark Nelsen