Part I - January 2020 Weather Discussion for the PNW

[TT-SEA]

Wednesday afternoon... main band has spun inland.

 

 

[TT-SEA]

Thursday morning...

 

[Requiem]

Still quite a bit of snow though. Hope this is the last of the gutting situation-- interestingly EURO seems to have intensified easterly flow.

[SilverFallsAndrew]

Cold onshore flow by hour 162... I'd rather see the GFS solution verify.

[VancouverIslandSouth]

How do you figure?

 

Looks like a fairly similar setup as other Arctic Front/CZ's we've seen recently (11/27/06, 1/10/07, 12/18/08, 11/22/10, etc.)

 

I can't remember a single time when an incoming arctic blast set off a CZ around or South of Seattle without giving snow to Skagit or Snohomish County first and I remember many times when it took longer to slip South than modeled. No guarantee that will be the case this time, but I'm just interested in your rationale.

 

The ECMWF has historically been pretty terrible in modeling precipitation in Arctic events here, tends to overdue how quickly things dry out and doesn't pick on the small scale features that give us most of our snow in transitions.

[Perturbed Member]

Thursday 4PM, just showery stuff. It's a decent snowfall for PDX but nowhere near previous runs. Just much less precip. Hopefully it does't continue to weaken.

 

[Esquimalt]

The ECMWF has historically been pretty terrible in modeling precipitation in Arctic events here, tends to overdue how quickly things dry out and doesn't pick on the small scale features that give us most of our snow in transitions.

I just checked and all of our most recent Arctic fronts that the previous poster mentioned yielded 10+ cm. Really good signs

[HighlandExperience]

Total snow from 10AM Sunday-10AM Monday... Certainly better for the central Puget Sound than the 12z and 18z.

 

Massive improvements for central sound

[Deweydog]

Additional runs ahead!

[GHweatherChris]

Good lord

[TT-SEA]

How do you figure?

 

Looks like a fairly similar setup as other Arctic Front/CZ's we've seen recently (11/27/06, 1/10/07, 12/18/08, 11/22/10, etc.)

 

I can't remember a single time when an incoming arctic blast set off a CZ around or South of Seattle without giving snow to Skagit or Snohomish County first and I remember many times when it took longer to slip South than modeled. No guarantee that will be the case this time, but I'm just interested in your rationale.

 

 

Because of the strong low racing inland and the roaring onshore flow behind it which pounds the Cascades.

 

Its pulling down arctic air... so you can call it an arctic front.   But 11/27/06 is a great example of a true arctic front.   The low that came through the day before is very much like what is shown for Sunday in the foothills and Cascades   Then the arctic front followed the next day and there was very little snow out here and lots of snow closer to the Sound.

[Requiem]

Weirdly our night model runs seem to be far more disappointing than our day runs. Just a little observation from the past few weeks.

[Weiner Warrior]

Jesus hates us

[Frontal Snowsquall]

[MossMan]

And the 12z Euro will look totally different precip wise. Too early to tell yet.

[TigerWoodsLibido]

There’s no way we see that much snow in southerly flow lol.

[GHweatherChris]

925 and 850 winds are now S,SW tonight.

[Omegaraptor]

Cold onshore flow by hour 162... I'd rather see the GFS solution verify.

 

Yeah the GFS and Euro are really different there. GFS really wants to keep that Columbia Basin cold pool in place for as long as possible while Euro wants to make it a quick hitter and done. Phil said this earlier:

 

"I do think the trends toward -EPO/additional amplification over the NE-Pacific are real..I’m definitely against the zonal/blah solutions in the longer range."

[TT-SEA]

And the 12z Euro will look totally different precip wise. Too early to tell yet.

 

 

I hope the timing is a little different at least.   I want to watch the game.  

[Weiner Warrior]

Hello Saturday

[Frontal Snowsquall]

The ECMWF has historically been pretty terrible in modeling precipitation in Arctic events here, tends to overdue how quickly things dry out and doesn't pick on the small scale features that give us most of our snow in transitions.

Good point.

[MossMan]

Because of the strong low racing inland and the roaring onshore flow behind it which pounds the Cascades.

 

Its pulling down arctic air... so you can call it an arctic front. But 11/27/06 is a great example of a true arctic front. The low that came through the day before is very much like what is shown for Sunday in the foothills and Cascades Then the arctic front followed the next day and there was very little snow out here and lots of snow closer to the Sound.

Ahhh...November 2006...

Nearly 18” of very wet heavy snow that started the day before the Arctic front moved through at Lake Goodwin...Still my #1 event in my lifetime!

[TT-SEA]

Another low spins up on Friday afternoon...

 

 

 

The first low actually does move inland an up into BC and then another low comes in.

 

That is very different than a stagnant low spinning the same place.  

[Perturbed Member]

00z and 12z snow maps look similar by late Friday despite differences with that low. This includes the transition event at the end of the week.

 

 

[GHweatherChris]

Tim is in a mood today... hi tier form!

[bainbridgekid]

This about as good a CZ signature as you'll ever see across the Central Sound. Important not to get caught up in details because the models can never nail down the exact strength and location of these in this setup. The fact it's even shown this clearly is what matters.

 

4PM Friday-10PM Friday.

 

[TT-SEA]

Ahhh...November 2006...

Nearly 18” of very wet heavy snow that started the day before the Arctic front moved through at Lake Goodwin...Still my #1 event in my lifetime!

 

I remember it was snowing here on Sunday morning and calm... and then the wind just roared in during the afternoon and all the snow melted and it was raining.   Then the snow came back and just dumped on us that evening. 

 

I think the path was south of this projected path of this low... you must have been on the north side of the track and stayed all snow.  

[VancouverIslandSouth]

Ahhh...November 2006...

Nearly 18” of very wet heavy snow that started the day before the Arctic front moved through at Lake Goodwin...Still my #1 event in my lifetime!

 

It's been awhile, I'd say we're due for a repeat. That was a very dynamic event, short but sweet.

[Cloud]

Another low spins up on Friday afternoon...

 

 

 

The first low actually does move inland an up into BC and then another low comes in.

 

That is very different than a stagnant low spinning the same place.  

 

This is super critical and we'll have to see how it trends. If it does show signs of making it inland, then there'll obviously be more snow for the interior. 

[TigerWoodsLibido]

Lol zero chance that verifies here.

[Shawn]

Weirdly our night model runs seem to be far more disappointing than our day runs. Just a little observation from the past few weeks.

 

 

I dont see why your disappointed.  With your elevation you would do great with gfs and euro.  I think you will be fine.

[TT-SEA]

This about as good a CZ signature as you'll ever see across the Central Sound. Important not to get caught up in details because the models can never nail down the exact strength and location of these in this setup. The fact it's even shown this clearly is what matters.

 

4PM Friday-10PM Friday.

 

qpf_006h.us_nw.png

 

 

Absolutely a c-zone.   Even if there was no cold air with this system... that is right where the c-zone would be behind this low.   And it would just be dumping rain along the I-90 corridor... except this time it will be snow.

[Requiem]

I dont see why your disappointed.  With your elevation you would do great with gfs and euro.  I think you will be fine.

 

I'm personally not disappointed, but I know others have been in comparison with model runs. IMO the runs tonight were fine, and we won't know exacts until later. A strong low with offshore flow is a recipe for at least some snow.

[GHweatherChris]

I'm personally not disappointed, but I know others have been in comparison with model runs. IMO the runs tonight were fine, and we won't know exacts until later. A strong low with offshore flow is a recipe for at least some snow.

Nice try, go to bed.

[TT-SEA]

00Z ECMWF is getting a little phallic on us tonight.    

 

[Requiem]

Nice try, go to bed.

 

Maybe later. 

[VancouverIslandSouth]

The 0z ECMWF shows a massive North Sound snowstorm next Saturday.

[Perturbed Member]

Quite ridiculous west-east and north-south gradient for snow fall across PDX on the GFS. 3 vs 8-10 inches. Must be some real impressive outflow.

 

[Frontal Snowsquall]

[Esquimalt]

Holy crap. 32 inches here by the end of the euro