Monday December 5

— YELLOW ALERT for WIND this weekend — 

Stormy December wx may be coming.  For this forecast, we’ll focus on 4 storms. Refill your morn’n Mug. 

A drab pattern is on tap for the first 3 days of this week.  Plenty of foggy bottoms and calm conditions.  Take advantage, if there is outdoor work to do, as we may be entering a classic stormy December period.  Admittedly, we have forecast such a 'run of storms' a few times this fall, to no avail.  However, if the models verify, planning ahead will prove prudent.  So, what’s the scoop?  

1st.  Rain returns late Wed night, moving in from the NW.  Vancouver Island & southern BC get wet first, then the rain will spread across the rest of the PNW by sunrise Thu Dec 8.  It will be a fast moving front, so expect showers to begin by late Thu.  It will be a cold front, with snow levels dropping again to low elevations once the front passes.  

2nd.  Right behind storm 1 will be a potentially STRONG storm hitting from the West sometime on late Fri / early Sat.  Just where the very deep centered Low moves onshore will determine which area get the strongest WIND FIELD.  Currently, models track No. 2 to make ‘landfall’ somewhere between Coos Bay & Astoria.  BUT, as it moves right up against the OR coast, some solutions literally circle the Low up towards central WA coast, then move it back to Astoria area by Saturday night.  Complicated and very difficult to pin down details.  However, we are not afraid to put out the possibilities; you decide how to plan accordingly.  Quite windy conditions may last hours.  Center pressure could be in the 980s mb and filling to 995 mb by Sat night; some solutions drop the Low to the 970s by Sat morning.  In general, this storm has been on the charts for a few days now, warranting a call-out here.  

3rd.  Yep, another storm - which could be the WETTEST of the series, is modeled to arrive by Mon morning, Dec 12, with the brunt of the storm hitting the region by Tue.  A very deep Low, potentially in the 960s mb!, may form and track just north of Vancouver Island.  The WIND FIELD for this storm will be large, so the PNW could be blown around again, although not as roughly as No. 2.  (Worth the mention: there have been solutions tracking this storm right up against the NW coast of WA; if this scenario were to verify, wind issues will be greatly expanded and stronger than the second system.)

4th.  After a relatively dry Wed and most of Thu, Dec 14,15, another batch of rain will sweep into the PNW late Thu and Fri.  Sat the 17th may be dry, with rain on/off from Sunday into the final week before Christmas.

Lots of changes are inevitable, of course, but for now, it will be prudent to plan ahead in case any or all of these strong storms make it onshore.  The wx this fall has been relatively tranquil, with long stretches between storms.  What is charting now is a rapid succession of storms, some quite powerful, beginning later this week.  Hold on.

The twelve month of 2022 has arrived.  Many activities & travel plans are set up for the holiday month.  We’ll keep you posted on any major wx episodes that may have significant impact.  Simply keep that morn’n beverage Mug ready.

Our current PNW chilly pattern will remain in place, with western valleys slowly warming up over the weekend to limit any snow threat.  Still, there is enough cold air being drawn in from the east through the Fraser & Columbia ‘Gaps’ to allow for snow showers whenever moisture arrives.  Such is the case over western WA this Fri morning.  The Low offshore will move south today & Sat, holding the bulk of the precip to the west.  A STRONG east wind will develop out of the Columbia River Gorge (and to a lesser extent, the Fraser River Gap), esp on Saturday.  It will ease up by Sunday night.  Snow showers over eastern OR on Sunday.  Overall, the weekend will remain DRY, chilly.

Next week is trending mostly DRY, with the east wind situation returning by late Thu Dec 8th, as another Low tracks south off the coast of WA & OR, bringing more rain to California.  The weekend of Dec 10,11 should be dry and, yes, December chilly.  

The prevailing model solution for the week of Dec 12-16 is for a return to the threat for very low elevation snowfall and bundle-up chilly conditions.  A repeat, if you will, of the past few days.  We’ll keep an eye on this.  Usually, it means snow in the foothills about town and tough travel going over the coast & Cascade ranges.   Expect it to be a wet week.

One aspect our team here is monitoring closely is the shift of a northern Siberian High into position as a precursor for a cold winter Christmas period in the PNW.  Not a forecast, just a ponder point for while we sip a morn’n bev.

We will continue on the edge for low elevation snow for the next several days.  Time for that refill, Patron.

It’s always difficult to get snow at the surface in the PNW, mainly because we are so close to the Pacific, which holds temps up.  The pool of cold air on the east of the Cascades will not be quite as cold as forecast several days ago, hindering our chance for west side snow.  However, there will be periods between now & Sunday that may allow for cold air to be drawn west to mix with the marine moisture resulting in a snow/rain mix at the surface, and snow in the foothills.  

Showers today will diminish before the next system moves in from the NW Tue & Wed.  The mid-week storm will be rather strong, with a Low pressure center deepening to approx 980-984 mb when it is west of Vancouver Island.  This will cause surface winds from the south to keep valley floors warm enough to hold off any valley snowfall.  That said, depending on the position of that Low, colder air drawn in from the east could keep the air mass cold enough for snow/rain mix, or just snow at times, esp later Wed into Thu as that Low drift south off the coast of Oregon.  You’re right: not a definitive forecast, because we remain On the Edge, indeed.

Another ‘repeat’ storm is modeled to follow nearly the identical path on Fri Dec 2.  Yep, there will remain the threat for low elevation snowfall.  Either way, it will be a very chilly, wet period as this week ends.  Sat & Sunday are trending drier, with chilly air mass and a moderated east wind.  Sunday night the next Low tracks just off the coast of BC and then right over OR.  Rain at the surface, snow in the coast & Cascade ranges.  North Puget Sound could see snow/rain mix, as the Fraser Outflow will turn on again, rushing colder, continental air into the region.  Familiar pattern.

A classic wet, mountain-snowpack-building pattern will set up for 1st full week of December.  A large pool of very cold air is charted to settle over the Gulf of Alaska during the week of Dec 5-9.  By mid-to-late week, that colder air will drive wet systems into the PNW, for very low elevation snowfall.  Too early to predict valley snow, but, if models verify, snow levels will be quite low (500-1,000 ft).  This pattern will be quite different from the current one because the coldest air will arrive from the northwest, hence any chance for snow will not be predicated on an east wind.  We’ll monitor this closely.  California should get some precip out of this pattern, late week.  

As the weekend of Dec 10,11 gets underway, an east wind may develop as High pressure, centered over the Continental Divide pushes air towards the PNW coast.  Concurrently, a Low will be moving south off the coast, missing the PNW, contributing to a large pressure difference, which sets up the strong east winds.   RAIN should return during the week of Dec 12-16, some of which may be moderate-to-heavy.  

Well, that's the current long-range outlook.  Change is inevitable, so keep that Mug of yours handy and step back into The WxCafé™️ on Friday for the latest revision.

Thanksgiving weekend update.  We’d like to keep this brief, but with the chance for SNOW coming, ‘yeah, right’.  Around here, we affectionately refer to snow as “The White”.  It is relatively rare for sea level snowfall around the region, so when there’s even a small chance for The White to occur, well, childlike excitement abounds; the forecast warrants a holiday Mug refill. 

A weak system will present rain and showers across the PNW today, Black Friday (most of the precip will fall north of Salem).  That will clear out, yielding a decent holiday weekend Saturday until after sunset.  The next, stronger AND COLDER system will move onshore, from north-to-south, while most of us sleep overnight Sat.  Windy.  This system has the potential to complicate holiday TRAVEL back home if one is driving over Cascade passes.  Rain will turn to showers on Sunday, with the air mass on the back side of this storm cold.  In fact, don’t be surprised to see snow & rain mixed (if not all The White at times) later on Sunday, esp in the northern Puget Sound area.  The warm ground, and diminishing moisture may limit accumulations, but it will be fun to watch.  

Quite chilly Monday & Tuesday (highs 30s to low 40s west side).  During this weekend storm, High pressure (>1040 mb) will begin to build over eastern Alaska, the Yukon (yes our fav place to peek for Arctic Events) and the Northwest Territories of Canada.  In the Wed, Thu, Fri period, Nov 30 -  Dec 2nd, we are anticipate the development of an “almost” modified Arctic Blast that will begin to shunt cold air out of the Fraser Gap, and eventually the Columbia River Gorge as another damp system tracks south along the coasts of BC, WA & OR.  Net effect: rain could turn to snow/rain mix at the surface; all snow above just a few hundred feet.  With the Low remaining off the coast (if verified), the colder air out of the Gaps will set up the snow or mixed pattern, esp overnight Thu.  On Fri, another coastal Low will follow the same path as above, with a bit colder air already in place, a snow/rain mix is probable, or it could remain as all snow if conditions are just right.  (We forecast an “almost” modified Arctic Blast because the bulk of the High pressure dome may skirt farther east, missing much of the region.  We’ll know more in our next update on the 28th.)

Saturday Dec 3rd The White is possible in portions of western OR, as the Fri Low mentioned above tracks into CA, drawing in cold air support from east of the Cascades as the moisture arrives.  Timing is everything.  IF this pattern verifies, a couple inches of snow is possible south of Salem.  By Sunday Dec 4, the moisture will be gone, the cold will be set in for a few days.  East winds will cease.  Morning fog possible.  

The week of Dec 5-9 is trending chilly & DRY, with an east wind picking up again, esp out of the Columbia Gorge.  Overall, though, temperatures will have moderated a bit, so not as cold as the weekend before.  Plain ole’ rain may return by the weekend of Dec 10.

—> Final note:  some model solutions dismiss the short-shots of moisture moving down the coasts, leaving the PNW mostly dry & frosty.  Southerly breezes also remove the surface snow threat, so position of the various Lows discussed above, is critical for valley snow/rain mix.  Either way, the coldest temps of the season are highly probable between now and Dec 6.  Snow events often take on their own, unplanned, attributes.  Be prepared.

Quip from the ’Net:  “I always knock on the fridge door before opening — just in case there’s a salad dressing."

The current long dry spell is nearing an end, although we do expect additional back-to-back days without rain in the near future.  Hot java ready.  Sip.

The next storm is on tap for tomorrow, Tuesday Nov 22.  A quick shot of rain & wind moving in from north-to-south, heading to Vancouver Island around midnight, then pushing into NW WA by daybreak.  The front should pack the strongest winds before noon Tue, esp for areas south of the Puget Sound into the Willamette Valley.  This will not be a dangerous wind event, just rather blustery given the unusually calm, dry wx of late.  By Wed, the event will be over, with clearing sky and dry conditions holding into early Fri.  Yes, Thanksgiving Day will be DRY, with a gusty east wind out of the Columbia River Gorge for the Portland area (yep, no fog).  Black Friday - a repeat play, with a relatively weak system moving in, north-to-south again so expect some precip mainly from Portland north; not too bad a day at all for much of western OR and east of the Cascades.

Post-Thanksgiving weekend, Nov 28 - Dec 2:  pleasant, calm day on Saturday the 26th (maybe morning fog in the usual places), then another system moves in along the same path as the previous storms.  This one will be weak in the PNW, but develop into a strong, news-maker storm for California Monday Nov 28th (then it makes big wind & snow in MT, WY).   Around the PNW, temps will be chilly again, with frost overnight in most locations.  Mixed model solutions for the last days of November.  Some runs keeps the PNW damp, other on the dry, chilly side, with another system tracking into southern OR and CA mid-week.  An E-NE outflow may develop out of the two Cascades Gaps - Fraser & Columbia - by late week.  Again, other model charts suggest a stormy start for December (and week’s end), with a low elevation snow producer (above 1,000 ft) by Fri.  

Let’s just hold off on a definitive early December forecast until after the big holiday.  For now, we’ll Mug call to a rather dry, chilly start for the 12th month. 

Our entire staff (me, myself & I) express thankfulness for family, friends & YOU - a Patron of The Weather Café®️- during this week of Thanksgiving.  This is our 28th year ☕️.