Lots of rain will continue to fall over the far NW corner of the PNW; trending drier for the rest.  Let’s go through the latest outlook.

 

From now until late Tue Nov 30, rain & showers will be almost continuous for portions of Vancouver Is, southern BC and the NW corner of WA.  Heed Nat’l Wx Service alerts as to flooding issues.  For SW WA, OR and ID, additional precip is charting for Saturday & early Monday.  Fog & dry conditions are likely to develop by Tue, excluding the far NW.

 

Ponder Points.  Here’s where the models begin to chart a mixed message (happening frequently this fall, for sure) - 

   1st scenario: generally dry and gradually cooler conditions for Wed Dec 1 through the end of next week.  Maybe some showers over the weekend of Dec 4,5, with a N-NE wind developing as cold High Pressure dome drops deep into the heartland, east of the Rockies.  Mild-to-warm (esp for OR) Sunday & Mon, Dec 5,6 before it turns colder with snow teasing Patrons north of Bellingham by Dec 9th.

   2nd scenario: coldest air of the season begins to drop into the PNW, with increasing chance for low level SNOW during the weekend of Dec 4,5.  A Low develops over northern CA, drawing 'snow-cold' air over OR & WA for snow showers becoming likely at the surface.  Ground may not be frozen yet, so accumulations may delay; cold Fraser Gap outflow - strong wind - could set up sometime that weekend, too.  (The pattern for Dec 4-12, 2021 has similarities to that of our very snowy Dec 2008.) Cold wx for much of CA, too, with the 2nd scenario.

 

Overall, both solutions do project our weather turning colder with very low snow levels as the week of Dec 13 gets under way.  

 

La Nina.  We are in a rather COLD La Nina pattern.  The image below (as of Nov 23, 2021) illustrates the cold (blue color) sea surface temperatures from the west coast of South America on east across the central tropical Pacific.  The Pacific Ocean offshore of the PNW is also running colder than average.  This is our second fall/winter with a La Nina pattern in place.  Yes, back-to-back La Nina winters do happen, as this will be the 6th time since 1999.  While not a certainty every time, La Nina winters generally produce more low level snowfall and above average precipitation in the PNW.  As the chart below indicates sea surface temps in the ‘middle’ of the tropical Pacific 0.75 - 2.0 degrees C colder than average.  We’ll see how all this plays out over the next 3 months. For now, be prepared for the chance for low elevation SNOW as the month of December gets underway.  It is probable. 

 

 

 

 

 

 

-Rufus

 

 

 

 

Early Sunday post because the coast is calling - we’ll be spending a few days at the beach before Thanksgiving.  Update, per usual, on Black Friday.  For now, here’s the latest outlook.

 

Weak system arrives later on Monday (north to south), bringing onshore a bit of rain or showers.  By Tue afternoon, partial clearing and morning fog will return in the usual places.  Dry, foggy Wed.  

 

Thanksgiving:  the next system will be the beginning of another rather extended WET cycle, with moderate-to-heavy rain.  It all begins in the north Wed night, as a moisture laden front moves onshore.  Western WA & BC first on Thanksgiving Day, then the system will drape over OR, as well, overnight Thanksgiving.  Black Friday will be a wet Friday to start, drying down by late afternoon.  Don’t put the rain gear away quite yet.  More rain hits Vancouver Is & NW WA by sunrise on Saturday, and making its way into OR by Sunday morning.  This system should not be quite as wet as the Thanksgiving storm.  Still, more rain where is really isn’t wanted at this time.

 

A short break in the action for early the week after Thanksgiving, but the rain returns first to the northern half of Vancouver Is Monday night, and spreads to all the PNW by sometime on Tue, Nov 30.  This storm will be a drencher - from northern CA to BC.  Fortunately for BC, much of the precip will be ‘held’ as snow in the mountains.  Good placement.  WET Wed Dec 1.  A powerful Pacific storm will rapidly move in overnight Wed, bringing WIND (!) and heavy rain Wed night through Thu Dec 2.  Early yet, but models charts a Low pressure center of 974-978 mb making landfall over Vancouver Is sometime Thu night.  If verified, damaging WIND will be likely over some portion of the PNW Thu night.  Freezing levels drop Fri morning after the strong cold front passes.  Frosty Sat Dec 4, if the sky clears in your area.  

 

What was earlier modeled to be cold, low-snow-pattern for the first weekend of Dec may be delayed, as models are mixed - could be wet and mild, with plenty of wind that weekend, or continue to the colder wet side, with snow levels falling through the weekend, on into the following week. 

 

Bottom line - early Dec should be chilly, with mountain snow and the chance for snow at the lowest elevations of the season.   For now, the parameters we discussed last time are still showing on the charts for early December — 'snow cold' air mass over the Gulf of Alaska & eastern AK & the Yukon, setting up strong Pacific storms for the PNW, along with colder conditions as the month unfolds.   It will be interesting to watch what actually develops. (We postponed the La Nina discussion until Fri.)

 

 

 

A pleasant weather weekend ahead, which is good news for cleanup & repairs from the flooding in the northern areas of the PNW.  Grab your morning beverage.

 

The break in rainfall will last through this weekend; Sunday will be the warmest, with plenty of sunshine after a possible frosty morning in many locations.  The next damp system is not due until later on Monday.  Even then, it will not be a heavy rain producer.  In fact, it could be more of a cloudy pattern, than one with lots of precip.  The weak Low will move into CA, ushering in some clouds & showers for the Golden State on Tue.  We can expect our weather to begin drying out dry on Tue, from north to south, as the Low drifts over CA.  There will be a wetter front moving into the PNW late Wed on into Thanksgiving.  Higher amounts of precip will fall over the NW corner of WA & Vancouver Is.  Showers on Black Friday.

 

The post-Thanksgiving weekend is trending moderately wet & breezy yet again, as another front sweeps in on Sat.  Similar to the previous front, the heaviest precip will be north of OR.  Timing may vary somewhat, as model projections have been indicating a VERY WET pattern returning to the PNW after Thanksgiving.  Some solutions brought back heavy rain during that weekend, others hold it off until during the week after Thanksgiving.  Either way, the relatively ‘calm’ weather in store for the PNW over the next 7 days will be appreciated & needed given the extended outlook.  

 

As November ends and December begins (week of Nov 29 - Dec 3), we may be in for heavy rainfall, WIND and the coldest storm fronts of the season, to date.  Each very wet front that arrives that week will progressively be colder & colder.  In fact, by the end of that week, the PNW could be seeing 'The White' in many low elevation locations, even teasing valley floors.  “There you go again”, some Patrons may be thinking.  Well, there is that possibility.  Sip on.

 

Ponder Point:  By late November, we see indications that a COLD High pressure dome may begin moving from NE Siberian on over Alaska and the Yukon. Will the high pressure increase to our ‘trigger’ range of 1040+ mb?  We’ll see.  Anyway, this cold air mass is charting to drop temps over the Gulf of Alaska and the interior (winter pattern), with subsequent support for strong Pacific storms over the PNW.  Each of those storms may bring colder air over our region.  This is similar to Dec 2008, if it actually develops.  For now, this is merely a projection, but one that could present low elevation snowfall that so many mention as an attribute of a strong La Nina winter in the PNW.  We are, indeed, in a cold La Nina pattern (we’ll present details on Monday).

 

Beforehand, the wet week after Thanksgiving will be quite wet, but with one key benefit relative to last week’s horrible flooding - the lowering freezing level will “hold” much of the precipitation in the mountains as snow.  (The freezing level was well over 8,000 ft in the last major rain event.)

 

The weekend of Dec 4,5 is trending either very WET with snow lowering to the footlhills, or generally wet with snow/rain mixed at the surface, turning to all snow late Sunday the 5th (esp over much of western WA).  Review the Ponder Point above as to why.  It will be interesting to see what  Nature actually does.

 

 

 

Our hearts go out to all Patrons in NW WA and southern BC - the heavy, flooding rains just won’t let go.  More to come before we get out of November.  Refill and read on.

 

As noted, serious flooding & landslides are impacting so many Patrons around the PNW.  For some, the moderate-to-heavy rainfall has continued daily since last week.  Temps have set records for WARMTH, which has held freezing levels high, sending all the heavy mountain slope precip right down rivers into the flooding lowlands.  Yikes.  There will be a few short breaks in the steady rain between now and the end of November.  However, while OR and much of western WA will dry out reasonably well, inches more rain will fall in NW WA and southern BC.  Now the details.

 

Today (Nov 15): a Low pressure system will rapidly move into the PNW.  This one is continuing heavy rain up north, but will also pack a short, but powerful WIND FIELD later today or tonight.  It will be the rapid rise in barometric pressure, post-frontal passage, that will kick-up quite a WIND. Willamette Valley and north will likely get 35-45 mph gusts, maybe 50+ in places.  (Yes, the last system we warned about did NOT pack the expected winds in OR; NW WA / BC did get hammered, though).  Power outages are probable up & down west side of the Cascades, adding misery to Patrons already struggling with floods up north.  Rainfall in OR should be in the half inch range at the valley floor; higher in the usual places; inches up north today/tonight.  Temperatures will drop RAPIDLY, so this will help ‘hold’ some of the precip in the mountains as SNOW (dropping below pass levels).

 

Dry most of Tue, Wed and early Thu.  Then, late Thu, WHAM - as another tightly packed Low pressure storm will come onshore around Astoria overnight Thu (! tracking inside the 130W).  Model solutions are quite variable on this one, but the pattern warrants our mention.  WINDY, esp or coast & willamette Valley Thu night.  WET.  Drying out Fri afternoon.  

 

Additional moderate-heavy rain is due to arrive over NW WA & southern BC late Saturday into Sunday.  Areas south of roughly Longview should remain mostly DRY.  Astoria will pick up some rain.  Oregon should be mild & dry Monday.  Repeat of the wet pattern is charted for Mon night, Nov 22, with portions of the north OR coast getting some rain; most of the precip to hit the already saturated NW WA, Vancouver Is, etc.  Tue Nov 23 is trending DRY, even for the far north zone we keep mentioning.   Pre-Thanksgiving, Wed, is looking generally dry everywhere (including much of the lower 48).

 

Thanksgiving Day:  dry everywhere except far NW WA, Vanc Is., and southern BC (sorry, but another round of heavy rain is on the charts).  That rain will let up on Black Fri.  Thankfully, the dry pattern should hold all the way through the long-US holiday weekend, even for our Canadian Patrons.  Let’s hope this verifies!

 

Rain returns to the PNW on Mon & Tue to end a very wet November.  California is modeled to be dry for the rest of November, excluding a few showers over northern CA from our windy storm overnight this Thu.

 

In Summary - total precipitation expected from today through Nov 30 is as follows:  Olympic Penn & Vancouver Island = 3.5"-8”; southern BC mountains (feeding the Fraser River) = 5”-12”; SW WA and Willamette Valley = another 1”-2”, with more in the coast & western slopes of the Cascades.  

 

 

 

Since late Wed, inches of rain have fallen for areas Salem north.   Let’s peek at what may happen between now and Thanksgiving.  Mug time.

 

Heavy rain should remain in play for OR north of Salem on into western WA & BC.  Patrons south of Salem have missed out on this long-stretch of steady rainfall.  Overall, things should begin to dry out for all regions as the weekend gets going, before another round of precipitation arrives late Sunday & Monday.  Notice how warm it has been?  (62 this morning in Albany.)  That will change on Monday, as a cold front arrives.  Snow levels will drop below the passes by Monday night.  Temps will be in the 40s for most areas west of the Cascades early next week.  By Thu, temps will slowly moderate over western OR (& remain cool in NW WA), with a wet system possible by Friday.  Could be windy over southern OR Thu night into Fri.

 

The weekend of Nov 20,21 is trending chilly, but dry overall.  Frosty morning on Sat and/or Sunday, if the sky clears where you fill that morning Mug.  Colder air (fed by a High pressure dome moving south out of interior Canada) will drop into the heartland of the US, so a big freeze is possible over the northern plains, upper midwest that weekend.  Pre-Thanksgiving winter slap.

 

Weather around the PNW during the days right before Thanksgiving will be mild in comparison.  Some model solutions bring more rain into the northern half of western WA & Vancouver area early Thanksgiving week; others keep the entire PNW on the dry side, with foggy bottoms, in the usual places.  Thanksgiving is trending less wet than earlier projections with mild temps, esp for OR.  We’ll see.

 

The extended Thanksgiving weekend is trending relatively calm across most of the lower 48 states, which will be decent for holiday travel.  Again, early yet, but at least the ‘view’ is favorable at this time.