December 2018 Weather in the Pacific Northwest

[Bryant]

#EastWindDensity

Since he dumbs it down for the audience here, he must be pretty smart, yeah? I'd love to see a prediction or 2 from the guy.

[Phil]

[Front Ranger]

I hope I eat my words, but unless we get something around New Years, I'm afraid we sit around in a Nino like regime through the majority, if not all, of January. This SSW is coming right as tropical forcing moves into the Pacific, and we will most likely see the jet extend, and an Alaskan vortex reemerge once again. This time however, the arctic flood gates will be open, and any trough that develops (most likely in the eastern 2/3's of the US) will feature much colder temps than we've seen thus far. Just my thoughts/opinion.

 

The Arctic floodgates are not usually open with an Alaskan vortex. Did you mean Aleutian low (further west +WPO but not +EPO)?

[Andrew.]

Down to 36.9 here now, dropping at a decent clip.

[Bryant]

The Arctic floodgates are not usually open with an Alaskan vortex. Did you mean Aleutian low (further west +WPO but not +EPO)?

I suppose I typically merge those phrases together, my apologies.

[MossMan]

44 when we left Kirkland, and it’s 37 at home.

[Geos]

38° here and dropping pretty good.

[Front Ranger]

I suppose I typically merge those phrases together, my apologies.

 

No problem. I think that happens a lot...to me, the difference in the two terms is basically vortexes 1000 mi apart, and one definitely leaves the door open for CONUS Arctic air more than the other, as you know. 

[Front Ranger]

Looking more and more like this will be a case where all models were confused in the mid range, none really had it right with any consistency, and the winning solution will be a compromise between the worst (some of the GFS runs) and the best (some of the other model runs a couple days ago).

[Gradient Keeper]

That friggin raging Western Pacific jet and a pair of very strong 951mb, 953mb lows over the Aleutians. Barf. We may not(probably won't) manage some chilly offshore flow and a cold pool now. Jeez. Ouch.

 

[Front Ranger]

The Euro went from this:

 

 

To this. In 2 days.

 

 

 

In retrospect, there was never a signal for meaningful -WPO with this pattern, which as I've pointed out before precedes the vast majority of PNW Arctic air events.

[Gradient Keeper]

The Euro went from this:

 

ecmwf_z500a_namer_8.png

 

To this. In 2 days.

 

ecmwf_z500a_namer_6.png

 

 

In retrospect, there was never a signal for meaningful -WPO with this pattern, which as I've pointed out before precedes the vast majority of PNW Arctic air events.

Without a -WPO we don't have the brick wall near the Aleutians shunting energy away. Yeah.

 

6z GFS in 2 hours 56 minutes!

[Gradient Keeper]

The differences from Days 4-7 from the Siberia arctic to the North Pacific are so profound I am not sure I'm buying this run. Perhaps a product of the SSW. From 498-504dam heights to sub 480dam heights. May be the PV split showing up on the ECMWF Op.

[Gradient Keeper]

Check out the past 4 ECMWF runs centered at Day 6 and 7. Look at the extreme changes occurring over the Siberian arctic. That's craziness. Big model shift coming but may not favor us.

 

Day 6 - https://imgur.com/10dUWa4

 

Day 7 - https://imgur.com/5g2XCwJ

[Front Ranger]

Maybe the SSW will end up screwing the West...ironic.

[Phil]

Maybe the SSW will end up screwing the West...ironic.

No way. In the absence of the SSW, there would be zero chance at Arctic air west of the Rockies at any point this winter. There’s too much antecedent STJ/westerly momentum in the subtropics to build Aleutian ridging of any kind without off-domain forcing(s).

[Gradient Keeper]

Maybe the SSW will end up screwing the West...ironic.

Probably, but what if the PV split heads into Alaska and it overpowers the Western Pacific jet/tropical forcing suppressing the jet extremely far to the south, or Piece of the PV moves into southeastern Siberia and buckles the Western Pacific jet.... Not my area of expertise, but wouldn't the mechanical forcing from the PV/split be strong enough to overpower any jet, ENSO or tropical forcing.

[Phil]

If we had a stable PV, we’d easily be looking at a 1991/92 repeat, if not worse. The low frequency system state is (and always was) unfavorable for western cold this winter. The question is whether this can be overcome by extreme wave amplification/vacillations in the AAM budget.

 

There’s no other way to get the job done. There won’t be any persistent -WPO or Aleutian ridging this winter. The only way to do it would be via the retrograding -EPO or old school tandem of -PNA/-NAO (dual non-dispersive anticyclones).

[Phil]

The +EPO/GOA vortex is arising via the tropical forcing and QBO/AAM budget(s), and these forcings are seasonal in nature.

 

Something will have to perturb the system state out of this quasi-stable feedback loop. Other than a SSW, I’m not sure what could possibly do it.

[MR.SNOWMIZER]

The +EPO/GOA vortex is arising via the tropical forcing and QBO/AAM budget(s), and these forcings are seasonal in nature.

Something will have to perturb the system state out of this quasi-stable feedback loop. Other than a SSW, I’m not sure what could possibly do it.

Old saint Nick could do it.

[Front Ranger]

No way. In the absence of the SSW, there would be zero chance at Arctic air west of the Rockies at any point this winter. There’s too much antecedent STJ/westerly momentum in the subtropics to build Aleutian ridging of any kind without off-domain forcing(s).

I don't think we can say "no way" or "zero chance" about these things. Just too many variables and factors.

[AbbyJr]

I could be completely wrong. Subseasonal/seasonal forecasting is very difficult. Even the best will f**k up from time to time (and I’m definitely *not* one of the best..there are some legit geniuses in this field and they’re literally on another dimensional plane).

 

If this SSW is going to help bring arctic air into the PNW, when do you expect we will see the models trend that direction? Like a few weeks from now?

[Guest Dome Buster]

Since he dumbs it down for the audience here, he must be pretty smart, yeah? I'd love to see a prediction or 2 from the guy.

I dont because you cannot with any reasonable accuracy. It is why the smart meteorologists dont make long range forecasts. What part of that is hard to understand? Guys like Phil get mad when I say this because it basically throws most of his diatribe out the window. He is threatened, hence he gets angry. His accuracy on long range is just what the statistics show. Very, very, very, very low. Did I mention it is very low? And a waste of time really.

[ShawniganLake]

Not much of a dry streak on the Euro tonight.

[Brian_in_Leavenworth]

Not much of a dry streak on the Euro tonight. A14C47B2-4406-43F3-996E-BC6ACFC4FB34.png

Can you post the snow maps please?

[ShawniganLake]

[HighlandExperience]

Old saint Nick could do it.

Old Saint Nick was wiped out by global warming.

[Gradient Keeper]

For what it's worth ($3.29?) the 00z CMCE ensembles weren't too shabby and colder than the Op though 5-9.

 

The Dalles. Quite a few members down to -7c or colder. Granted there are a chunk of them -5c or warmer though.

 

Spokane ensembles are even colder of course. This suggests the Canadian may veer back to backdoor blast potential.

[El_Nina]

The decrease of arctic blasts is always talked about and seems to be the main talking point when we're talking about our current climate. But I think the fact that the persistence of warm anomalies, along with record long dry stretches and an increase in very heavy warm rain in the winter shouldn't be tossed aside. If you look at some of the anomalies the past 5ish years it is astounding. Who knows if it will continue going forward, but even as it is now, it's something to at least remember.

[snow_wizard]

Holy crap!  The ECMWF just obliterates the ridge early in week two.  I mean the thing just gets CRUSHED.  The East ends up getting completely cheated out of any cold at all with that solution.

 

As for us I still see the next week being pretty cold overall with two moderate cold shots followed by a brief period of fake / preserved cold.  With the Nino about to get the life squeezed out of it January is very much on the table for us.

[Requiem]

Holy crap!  The ECMWF just obliterates the ridge early in week two.  I mean the thing just gets CRUSHED.  The East ends up getting completely cheated out of any cold at all with that solution.

 

As for us I still see the next week being pretty cold overall with two moderate cold shots followed by a brief period of fake / preserved cold.  With the Nino about to get the life squeezed out of it January is very much on the table for us.

 

Schadenfreude. 

[Gradient Keeper]

Hmmm, this is also mildly interesting. 6z NAM 500mb looks pretty good. Nice strong ridge, cut-off under block, merger looks good, and heights suppressing quickly over southern BC as offshore ridge pulls to the west/mergers. Lacking a great deal of amplification, but this is far better than previous runs.

[Andrew.]

Rain/snow mix here this morning, 36.9 degrees in the West Hills of Portland.

 

[TT-SEA]

Saw a couple stray snowflakes here.    Precip is very light... temp is 36 and the dewpoint is 30.

[Front Ranger]

The Euro went from this:

 

ecmwf_z500a_namer_8.png

 

To this. In 2 days.

 

ecmwf_z500a_namer_6.png

 

 

In retrospect, there was never a signal for meaningful -WPO with this pattern, which as I've pointed out before precedes the vast majority of PNW Arctic air events.

 

And now, GFS failure at even closer range.

 

Today's GFS for three days out:

 

 

And just 24 hours ago it was:

 

[MR.SNOWMIZER]

Almost all snow here and 35

[MR.SNOWMIZER]

That radar on komo is accurately showing blue over me.

[TigerWoodsLibido]

38 with light rain.

[Timmy]

The gem shows an interesting setup with a ridge sitting over us in the extended, a pocket of -10c 850 temps in se Oregon and +5 everywhere else. It would likely be a pretty incredible low level cold setup, 2m temps show highs below freezing for west side locations.

[TT-SEA]

The gem shows an interesting setup with a ridge sitting over us in the extended, a pocket of -10c 850 temps in se Oregon and +5 everywhere else. It would likely be a pretty incredible low level cold setup, 2m temps show highs below freezing for west side locations.

 

12Z GFS is crashing the ridge hard by day 8 with heavy rain.