Rufus at the WxCafe® heralds an eventual thaw but not quite yet . . . Robin
Friday December 6
The freezer door will be closed soon. Until then, another, even colder Arctic air mass will arrived over the weekend. Low temperature records tied or broken around the entire west coast yesterday morning (lots of those were established in 1972). More will fall by Monday. Is your hot morning beverage ready? Let's get that door closed.
Spotty light snow falling from Astoria to Portland to Eugene as coffee is poured here at The WxCafe (TM) this morning. Much of the southern Willamette Valley, Medford, northern CA should get notable snow by Saturday. The leading edge of the next Arctic Blast is now pushing south. Fraser Gap outflow picking up again, with gusts in Lynden/Bellingham nearing 40 mph, temps 20-22, dew point minus 1. That defines COLD! As many wx forecasters have noted, mornings lows by Sunday & Monday will crash to some of the coldest temps in many years. Single digit readings probable where snow has fallen in portions of Willamette Valley, etc. Sub-zero temps east of the Cascades will be numerous. The end is in sight.
Warmer, westerly flow will slowly arrive in the Tues night to Thur morning timeframe. As the warm front approaches, our usual pattern of snow turning to freezing rain, then rain will take place. If the overriding precip arrives slow enough, w/o surface breezes from the south, then many west side locations could, indeed, have a round of snow. Freezing rain will also challenge travel until all this melts away. Be alert for the "spotties" - patches of ice on roads that warm up last.
The main feature mid-week will be a return to moderate-to-heavy rainfall (lots of mountain snow, too), esp west of the Cascades. If the models are correct (some have vacilated back 'n forth on a threat for colder air again by Dec 19-22), an extended series of wet systems will stream into the PNW from mid-week on through at least Dec 23. Many will be pleased with that return to our normal, relatively mild rainy weather. Oh, conditions will favor a good snowpack period.
So, the unusually long period of very cold weather will end soon. Patience patrons!
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OSU Plant Clinic December Hightlights - Things to look for in December. Robin
Monday December 2
Fortunately for holiday travelers around the PNW, the key feature of the week - the Arctic Blast - delayed itself until tonight. Progressively colder air will push into the region today & tomorrow. In fact, the temperature at your location as you read this prognostication will be the warmest it will be in a week or longer.
The leading edge: Early morning light snow showers, along with some freezing rain, clipping Bellingham/Lynden is just the beginning of this event. Later today, the Fraser outflow will get cranky, with bitterly cold Arctic air slamming through the Fraser Gap and expanding southward. Eastern basins will be impacted later tonight, as well, as the Arctic air fills in behind the front. SNOW showers remain probable at all locations by Tues morning, but limited moisture source, so photo-op accumulations not likely unless one gets into the hills. Columbia Gorge outflow will also come into play.
Big impact this week will be the sub-freezing temps, as colder air moves in by Wednesday. If you get above freezing during the afternoon hours, you will be in a rare location - like the coast, or near large body of water. Overnight lows in the teens west side and below zero to single digits east. Extremely cold in the mountains.
Models toy with a weak surface disturbance setting up sometime Thur or Fri for SNOW SHOWERS in many locations, esp western OR. This is iffy, but warrants mentioning. Latest solutions for the weekend indicate yet another blast of Arctic air driving south into the PNW keeping the region unseasonably cold until at least Tues Dec 10. Maybe, just maybe a slow warm-up will occur by the middle of next week. Possible for surface system to approach from the northwest, first threatening snow, then freezing rain and finally rain.
Generally, models point towards a VERY WET, stormy period starting the weekend of Dec 14 and lasting through the 19th. Lots of mountain snow, STRONG WINDS, and inches of rainfall. The interesting feature of the extended period is that the PNW will remain right on the edge of cold air to the north, seasonal air to the south. The last storm in the series just mentioned could, indeed, be the forerunner of another Arctic event and a snowy opening to Christmas week. (Oh yeah, your WxCafe (TM) is way ahead of itself with that one!!)
You've pondered & prepped for subfreezing temps, now it's time. Next update Friday, unless an earlier note is warranted.
Below is a special statement from Rufus at The WxCafe™ about a cold snap for next week - be sure to prepare for this winter weather event. Happy Thanksgiving to all! Heather
Wednesday November 27
A modified Arctic front will push south out of Canada into the PNW in the late Sunday night thru Monday night time frame. Timing is not precise, hence the wide window for arrival. Breezy rainfall on Sunday will transition to lowering snowfall levels by Monday. Post-holiday travel home over the mountains will be difficult. If the system arrives earlier, even the coast range could see snowfall on Sunday. SNOW showers will be probable at all elevations by Monday night/Tuesday. The dry, cold air mass will preclude any major accumulations; still, it will be winter-like for everyone.
Temps will plummet into single digits to just below zero in the colder locations east of the Cascades, down into the teens west side in wind sheltered areas. Fraser & Columbia river outflows will kick up quite a cold wind from the east/northeast. How long will this last? Earlier solutions held the region in the freezer for several days; current solutions hint of a slow warming by Fri/Sat, Dec 6,7. Another cold clipper may touch us by Sunday/Monday Dec 8,9 for rain at the surface, snow at low elevations & in the eastern basins. We'll see. Either way, this event will be the coldest in quite some time, so be prepared (livestock water, plumbing, etc).
Extended outlook remains mixed, with either continued cold, dry or slow warming under a more westerly flow & some showers. The transition period, per usual, may threaten freezing rain. Time will tell.
Next update on Friday. Enjoy your holiday.