December Weather In the PNW

[ShawniganLake]

The past 10 days was really close to being good for Washington state. It’s been below freezing for 10 straight days in the Fraser Valley. Tons of cold air in the BC interior. -25F near our cabin this morning. Just a total lack of north wind density.

[Phil]

This is why mets are reluctant to post here. The warm pool index must be treated differently depending on the timescale of your analysis period. The warm pool alters the pattern in differently depending on the boundary conditions at the time.

 

There’s a reason I compared the last four winters in my analysis.

[Front Ranger]

A mile down the road from cabin. Couger was eating a grouse and walked only 20ft off road and watched us. Pretty cool.

 

That's awesome. At first I didn't see it, but once my eyes focused on it, I don't see how I missed it. Lucky, I've never seen a cougar in the wild. I have seen a bobcat a couple times and once what I'm pretty sure was a lynx.

[Front Ranger]

This is why mets are reluctant to post here. The warm pool index must be treated differently depending on the timescale of your analysis period. The warm pool alters the pattern in differently depending on the boundary conditions at the time.

 

There’s a reason I compared the last four winters in my analysis.

 

But you were also saying the warm pool was what screwed up a short term period. 

 

Can't have it one way and not the other.

[ShawniganLake]

A mile down the road from cabin. Couger was eating a grouse and walked only 20ft off road and watched us. Pretty cool.

That is cool. There are cougar everywhere on Vancouver Island, but they are elusive. Rarely are they seen.

[MR.SNOWMIZER]

That's awesome. At first I didn't see it, but once my eyes focused on it, I don't see how I missed it. Lucky, I've never seen a cougar in the wild. I have seen a bobcat a couple times and once what I'm pretty sure was a lynx.

They are a awesome animal to see. Bu far the coolest animal I've seen over here is a Moose. They are so big they look like they dont belong in the woods.

[Front Ranger]

Even just comparing the two maps of the last 4 winters to the warm pool map, there are some significant differences in blocking signals over Alaska, the Aleutians, and Siberia. I don't expect a perfect match, of course, but those areas are pretty key to what happens downstream. They were a big part of why 2013-14 and 2016-17 were cold in the PNW.

[Phil]

If I extend the timeframe out to a month, what happens? More similarities emerge in the WHEM. This following a lack of warm pool forcing from Sep 15th to Nov 15th

 

[Front Ranger]

They are a awesome animal to see. Bu far the coolest animal I've seen over here is a Moose. They are so big they look like they dont belong in the woods.

 

I did see a moose in the wild for the first time this summer! It was about 150 yards away in a swampy area at the base of Mt. Bierstadt, one of the 14ers I climbed.

[Deweydog]

Good lord...

[Front Ranger]

Good lord...

 

You've been pulled into the fray before and will again. In fact, I've played a large role in pulling you in several times and take great pride in that. 

[Phil]

But you were also saying the warm pool was what screwed up a short term period.

 

Can't have it one way and not the other.

Dude, of course there are short term effects. That doesn’t mean the effects will be spatially analogous across all domains, every time. Boundary conditions are fluid and ever changing. There are particular similarities like Hadley Cell expansion/poleward jets and eddy fluxes, but their spatial orientations can vary.

 

Get it?

[Front Ranger]

If I extend the timeframe out to a month, what happens? More similarities emerge in the WHEM. This following a lack of warm pool forcing from Sep 15th to Nov 15th

 

 

So in your mind, where does the warm pool rank in terms of seasonal forcings? Ahead of ENSO? QBO? Solar? AO/NAO tendencies?

 

I'm honestly wondering. It seems like way more than ever before is now being credited to the WHEM warm pool, but I could be wrong.

[Phil]

Even just comparing the two maps of the last 4 winters to the warm pool map, there are some significant differences in blocking signals over Alaska, the Aleutians, and Siberia. I don't expect a perfect match, of course, but those areas are pretty key to what happens downstream. They were a big part of why 2013-14 and 2016-17 were cold in the PNW.

Did I ever say the result would be the same every time?

 

Heck, if I thought an expanded warm pool would preclude an Arctic blast in the PNW, would I have predicted one this year? It didn’t preclude a blast in 2013/14, either.

[Phil]

I think it’s safe to say that an expanded, NE-shifted west-Pacific warm pool makes it more difficult for an Arctic blast to occur in the PNW due to its effects on the Pacific Hadley Cell and NAM/PV/NAO. I think it’s playing the lead role in forcing the western ridging to open this winter.

 

I don’t think it precludes an Arctic blast.

[Front Ranger]

Did I ever say the result would be the same every time?

 

Heck, if I thought an expanded warm pool would preclude an Arctic blast in the PNW, would I have predicted one this year? It didn’t preclude a blast in 2013/14, either.

 

I guess that's the part I'm having trouble understanding. We know the warm pool is there, we know the PNW can still get cold when it's there, so how exactly do we know that's what kept your most recent blast call from working out?

[seattleweatherguy]

I think it’s safe to say that an expanded, NE-shifted west-Pacific warm pool makes it more difficult for an Arctic blast to occur in the PNW due to its effects on the Pacific Hadley Cell and NAM/PV/NAO. I think it’s playing the lead role in forcing the western ridging to open this winter.

 

I don’t think it precludes an Arctic blast.

Would this same pattern open the pnw to a colder summer?

[Phil]

I guess that's the part I'm having trouble understanding. We know the warm pool is there, we know the PNW can still get cold when it's there, so how exactly do we know that's what kept your most recent blast call from working out?

Because we can trace the persistent western North-American anticyclone (ridge) as a direct response to WAFs/diabatic forcing from convection located over the off-equator west-Pacific.

 

I can demonstrate this quantitatively, if you’d like. It’s actually fascinating to look at.

[Front Ranger]

I think it’s safe to say that an expanded, NE-shifted west-Pacific warm pool makes it more difficult for an Arctic blast to occur in the PNW due to its effects on the Pacific Hadley Cell and NAM/PV/NAO. I think it’s playing the lead role in forcing the western ridging to open this winter.

 

I don’t think it precludes an Arctic blast.

 

As far as similar ENSO winters go, I believe the ones with a warm pool included: 2016-17, 2013-14, 1996-97, 1995-96, 1989-90, 1985-86, 1981-82, 1961-62, and 1959-60. All all of those had significant cold/snow in the PNW, with several major blasts. FWIW...

[Jesse]

The past 10 days was really close to being good for Washington state. It’s been below freezing for 10 straight days in the Fraser Valley. Tons of cold air in the BC interior. -25F near our cabin this morning. Just a total lack of north wind density.

Could have been the pattern that Phil was sniffing out for this period. Got ruined by that wascally WPAC though.

[Gradient Keeper]

Split flow vs blocking maintains. Quite different.

Yeah. Very stark differences.

 

18z GFS in 17 minutes

12z ECMWF (1st of 2018! in 20 hours 36 minutes)

[MossMan]

Still only 33 degrees here!

[Phil]

As far as similar ENSO winters go, I believe the ones with a warm pool included: 2016-17, 2013-14, 1996-97, 1995-96, 1989-90, 1985-86, 1981-82, 1961-62, and 1959-60. All all of those had significant cold/snow in the PNW, with several major blasts. FWIW...

Where are you seeing this? There’s a warm pool every winter, but it’s structure varies over time.

 

The warm pool was:

 

- retracted and SW-shifted in 1959/60 and 1961/62

- retracted and NE-shifted in 1981-82, 1985/86, and 1989/90

- expanded and neutral in location in 1995/96 and 1996/97

- expanded and NE-shifted in 2013/14

- neutral and NE-shifted in 2016/17

[Phil]

You've been pulled into the fray before and will again. In fact, I've played a large role in pulling you in several times and take great pride in that.

That’s a skill you have that I certainly don’t.

[MossMan]

Seahawks win, Falcons loose, and the 18z starts an epically amazing trend!

[Phil]

So in your mind, where does the warm pool rank in terms of seasonal forcings? Ahead of ENSO? QBO? Solar? AO/NAO tendencies?

 

I'm honestly wondering. It seems like way more than ever before is now being credited to the WHEM warm pool, but I could be wrong.

I’m definitely beginning to value it more. It’d rate it as less important than ENSO/QBO, and on-par with solar.

 

I don’t really think of AO/NAO as “forcings” (from the perspective of making a seasonal forecast) as much as components of (or responses to) boundary conditions set by lower frequency forcings like solar/QBO/ENSO, and especially longer term changes in equator/pole deep ocean heat balance.

[Deweydog]

You've been pulled into the fray before and will again. In fact, I've played a large role in pulling you in several times and take great pride in that.

I'm sure you guys will get it all figured out this time.

 

#hisandhersbusts

[TigerWoodsLibido]

You know it's bad when the Seahawks are still looking better than the models.

[ShawniganLake]

Denying the warm pool here is like denying 2+2=4, in my opinion,

 

How can it possibly get any clearer than this?

 

 

If only the GEFS actually looked that good.

[crf450ish]

Ok dude, we get it. You're very much in danger of entering broken record territory.

Dude this entire forum is a broken record when the models don’t deliver what people want....

 

It’s the same thing every. single. year.

[TT-SEA]

Gorgeous day!  

[MossMan]

Gorgeous day!

Sunny and 33 still. I’m suprised with how cool it is today here.

[SilverFallsAndrew]

Looks like a surprise 50 at PDX today... The weather already thinks it is January!

[Deweydog]

Looks like a surprise 50 at PDX today... The weather already thinks it is January!

Definitely a little downslope help today.

[SilverFallsAndrew]

18z could be worse.

[Winterdog]

18z could be worse.

Some backdoor chill with a nice ridge 500 miles too far east but overall pretty boring.

[Deweydog]

Those east winds on #MLK look chilly.

[MossMan]

Some backdoor chill with a nice ridge 500 miles too far east but overall pretty boring.

Baby steps and notches!!

[Winterdog]

Baby steps and notches!!

You must mean Baby backs and nachos. 32.4F here now after a high of 35 at 12:30am. 

[snow_wizard]

The 18z at least achieved the status of not being gag worthy.  Pretty notable improvement in several aspects through much of the run.  Looking like a pretty good shot at a minor cold snap around Jan 6 or 7.  Amazing how many of those minor ones we are pulling off.  The 18z actually shows some lowland snow with that feature.