It’s nice to see the forecast proceeding according to plan. At noon Friday, we are seeing a few spots of drizzle and flurries as the thin layer cold arctic air has arrived in the metro area. It’s pushing up the leftover showery airmass, rising air condenses and showers form = snow flurries right now. The cold air came down from the north and is now arriving out of the Gorge in the eastern metro area. Vista House just east of Troutdale dropped from 34 to 24 in the past hour and a half and east wind is already gusting over 40 out there. That’s the BEST weather that spot will see until Wednesday next week. Portland (airport) has dropped from 40 to 33. So the northern half of metro area is now frozen and southern half lingering near 40.
Many of you have been seeing flurries, but I think most likely that’s it for the rest of the day. Look at the current radar loop and you see most snow showers are in the southern metro area, along the arctic front as it plunges south.
We aren’t seeing any great enhancement in the radar and the atmosphere will continue to dry out through tonight from the metro area northward as the bitterly cold arctic airmass blasts in from the east. So our forecast of “FLURRIES TO ONE INCH” will work out fine. Of course there are wet roads in spots so expect icy areas here and there as you head home this afternoon/evening. Lots of schools are letting kids out in the next 2 hours and I think in general we are in good shape through the evening. Portland National Weather Service has dumped the Winter Storm Watches and converted them to warnings. The Portland metro area down to Salem is under a Winter Storm Warning tomorrow, western Gorge (Cascade Locks westward) a Blizzard Warning, and an Ice Storm Warning is up for the central/southern Willamette Valley. Coastline and lower Columbia River areas are under a Winter Weather Advisory. That means not as severe in those areas.
- This evening and overnight the temperature drops…drops…and drops while the east wind ramps up. Windchill temps down around zero by sunrise in the usual east wind spots! We bottom out in the upper teens by sunrise. Models have done surprisingly well showing the intensity of the cold; I was doubtful but observations “upstream” are really cold!
- Our forecast for tomorrow doesn’t need to change…we’re going for 1-6″ snowfall from Salem through metro area & north to Longview plus east through the Gorge. Most likely 2-6″ in the metro area and 6″ in the Gorge.
- This will be accompanied by ice pellets and/or freezing rain at times Saturday. The wide variation in snow totals is because more of the precipitation in the southern half of the metro area will be in the form of ice pellets and freezing rain. We all get about the same precipitation, just in different forms
- Tomorrow may be the coldest/windiest day Portland has experienced in 3 decades! The inner/eastern portion of the metro area will likely stay in the teens with a strong east wind. The last time PDX didn’t get to 20 degrees was in December 1990. Expect power outages in the usual east wind spots since this time it’ll be a bit stronger than normal. This will cause blowing and drifting snow in those areas too. We do not expect strong wind in most of the region; this is localized to mainly central/east metro area plus Cascades.
- Tomorrow will feature mainly freezing rain and ice pellets south of the metro area down to Eugene. Expect power outages due to thick ice glazing.
- All precipitation ends tomorrow night and Sunday should be mainly cloudy and cold. East wind backs off to the usual areas; more reasonable that day. But we stay frozen.
- MLK Day Monday will still be cold with that east wind blowing in the usual spots, but other areas rise to freezing.
Whatever falls will still be on the ground through Monday morning snow-wise. In the metro area most un-treated roads will probably still have some snow left on them Tuesday morning too.
Models are in pretty good agreement on total precipitation tomorrow, but precipitation-type makes all the difference for accumulation of snow vs. freezing rain vs. ice pellets in any one location. ECMWF ensemble average snowfall (Saturday) has hardly changed in the last 1.5 days.
Worried about lack of snow south metro and valley? That’s because more of the precip falls as freezing rain and ice pellets there. Look at the NAM forecast for ice pellets; it’s shoving a solid warm layer overhead so snowflakes melt into raindrops that then re-freeze into those pellets before hitting the ground.
Text output from IBM’s GRAF model (most TV stations use this). It shows the mix of snow (about 3″) over PDX, then about 1/3″ ice glazing during the afternoon tomorrow. For the record, if temperatures and wind are as forecast, this will be the coldest/windiest/iciest day I’ve seen in my career here. I’ve seen more snow, more ice, and more wind, plus colder temps. But I’ve never seen such an extreme combo of all three as it is forecasting tomorrow afternoon
That’s it for today. Stay warm! No further weather blog updates until tomorrow because I’ll be on TV at 4, 5, 6, 8, 9, 10, 11pm. You can find me there!
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