Arctic Air, Snow Track Update
By Rod Hill on 2023-01-25
The update confirmed from the last 3 weather model runs is much drier and moisture starved as the
cold air advection is largely blocked from Pacific moisture. Also, rapidly developing east winds Sunday
will bring additional dry air advection. The timing of the Canadian / Arctic front continues to be Saturday
evening and overnight into Portland. Evening rain showers will transition into snow overnight and flurries
may rapidly end Sunday morning. While snow showers are likely, there may not be enough moisture for
snow to cover the ground. Still, the valley floor could wake up Sunday morning to scattered dustings
of snow. Areas higher in elevation near 1,000 feet and above will tap into a faster snow transition Saturday
night and could see up to 3” of snow on the ground Sunday morning. Snow amounts over Cascade passes
will also be limited, but accumulations of 6” look to be decent call.
East winds blowing Sunday into Monday may reach 40-50 mph gusts near the gorge, while much of the valley
will see winds between 15-30 mph. The wind will produce valley wind chill factors down to 20 degrees during
daytime hours. Winds will ease Tuesday and may become light away from the gorge.
The latest GFS-American model for Portland shows 20 degrees Monday morning and 21 Tuesday. With
dew points from the Arctic surge in the single digits. Wind protected valley locations should easily see low
temps in the teens with coldest numbers approaching 15 degrees. A hard freeze in the 20s is also a good
bet at the coast.
Other city forecast from NWS Sunday - Tuesday, lows and highs:
Astoria: 33/41 24/37 27/40
Salem: 30/38 20/33 19/36
Eugene: 29/38 19/34 18/37
Slow moderation of temps will take hold Wednesday and Thursday. The next Pacific front is currently
on track for Friday of next week and is expected to weaken as it pushes inland. Although I am watching wind
patterns, at this time the moisture Friday at least outside of the gorge is likely to be rain.
The overall pattern for February continues to show periods of below normal temps. Here is Euro 5,000’ air mass
map Feb. 13th, showing cold Canadian air blanketing much of the west.
Rod Hill
Valley Wind Advisory, Heavy Rain Coming