December 2014 Observations for the Pacific Northwest

[bainbridgekid]

The 18z parallel GFS shows Arctic air just about to enter WA at day 10.

 

This is sure a weird situation.  We may go into a big cold wave with almost no snow on the ground in the mountains.  A normal warm ENSO winter would actually do better in the mountains the first half of the winter.  Expect big surprises to come.

The block is beautiful but it's hard to imagine arctic air making it here with such a deep SE trough.

 

http://www.tropicaltidbits.com/analysis/models/gfsp/2014121518/gfsp_z500a_namer_41.png

[snow_wizard]

The block is beautiful but it's hard to imagine arctic air making it here with such a deep SE trough.

 

 

I would guess if that pattern happens a SE ridge will appear rather quickly.  I seem to remember we had a cold snap or two recently where the SE was strangely missing in the models also.

[snow_wizard]

It happened in December 1968. Needless to say, that's not normal.

 

I wonder if it may have happened in late Jan 1893 also.

[Phil]

I would guess if that pattern happens a SE ridge will appear rather quickly. I seem to remember we had a cold snap or two recently where the SE was strangely missing in the models also.

There will be no significant SE ridge. There's no sustainable, low-frequency forcing available for one.

 

In a situation like this, a SE ridge isn't necessary anyway. You're going to have coast-to-coast cold, with the heart of it directed into the Central US.

[Phil]

It happened in December 1968. Needless to say, that's not normal.

True, but I was referring to the actual numbers, not the anomalies. I could see a huge western blast in early January if everything works out..or it could slide just east. Going to be a close call.

 

The 1968-69 winter was largely a result of the Strat-forced -NAO coupling with the tropically forced -PNA..that's hard for the system to do, but it's somewhat similar to what the first 10 days of January might look like. If the NAO fails or is delayed this time, then we're left with a reincarnation of January 1994/2014..

[Deweydog]

It happened in December 1968. Needless to say, that's not normal.

February 1989 was probably about as close as we get to it as well.

[SilverFallsAndrew]

The latest Euro weeklies are less than inspiring.

[Bryant]

There will be no significant SE ridge. There's no sustainable, low-frequency forcing available for one.

 

In a situation like this, a SE ridge isn't necessary anyway. You're going to have coast-to-coast cold, with the heart of it directed into the Central US.

Apparently the Euro weeklies show a developing SE Ridge come New Year time frame. Haven't seen them myself

[wx_statman]

True, but I was referring to the actual numbers, not the anomalies. I could see a huge western blast in early January if everything works out..or it could slide just east. Going to be a close call.

The 1968-69 winter was largely a result of the Strat-forced -NAO coupling with the tropically forced -PNA..that's hard for the system to do, but it's somewhat similar to what the first 10 days of January might look like. If the NAO fails or is delayed this time, then we're left with a reincarnation of January 1994/2014..

Exactly, on actual numbers. December 1968 produced -21/-48 in Winthrop, WA and -27/-50 in Eureka, MT. This is west of the divide.

[ShawniganLake]

The latest Euro weeklies are less than inspiring.

Mark posted the wrong maps.  Take a second look.  Not bad at all.  Big time ridging through the Aleutians and western Alaska, Christmas through New years. 

[wx_statman]

February 1989 was probably about as close as we get to it as well.

That cold wave actually produced highs around -25 and lows around -40 in MT and WY. The coldest air still went east of the divide...

[SilverFallsAndrew]

 

Mark posted the wrong maps.  Take a second look.  Not bad at all.  Big time ridging through the Aleutians and western Alaska, Christmas through New years. 

 

 

He did?! What a warm bias.

[Phil]

Exactly, on actual numbers. December 1968 produced -21/-48 in Winthrop, WA and -27/-50 in Eureka, MT. This is west of the divide.

So, "west of the continental divide" is analogous to the PNW realm? I'm no geography buff, but that's new to me.

[SilverFallsAndrew]

Just saw the EURO weeklies. Christmas through mid-January could be cold.

[ShawniganLake]

Latest tweet from Brett Anderson.

 

[Phil]

Apparently the Euro weeklies show a developing SE Ridge come New Year time frame. Haven't seen them myself

I see something that resembles a SW Atlantic ridge going up in response to the deep North American trough, but I wouldn't call it a SE ridge..the weeklies have a -NAO/-AO/-PNA going..looks a lot like hybrid of 1968-69 and 1978-79..

 

The big western cold is coming, but not until around/after New Years, IMO..and even then, I still think it'll be a coast-to-coast deal..

[Snow]

Just saw the EURO weeklies. Christmas through mid-January could be cold.

Yeah that omega block the EURO shows is in a fantastic spot. I don't see any way Arctic air doesn't dive down to the PNW.

[BLI snowman]

So, "west of the continental divide" is analogous to the PNW realm? I'm no geography buff, but that's new to me.

 

Just out of curiosity, what region do you think Winthrop, WA is?

[Deweydog]

Just out of curiosity, what region do you think Winthrop, WA is?

If he's been there he know it's the wild west.

[Phil]

Just out of curiosity, what region do you think Winthrop, WA is?

Geographically, I look at state borders. That's it, I don't give a crap about topographically-induced microclimactic variations over short distances when looking at things from an upper level perspective. That's something a mesoscale meteorologist would look at..that's not what I do..

[wx_statman]

So, "west of the continental divide" is analogous to the PNW realm? I'm no geography buff, but that's new to me.

Glad to help.

[Phil]

Glad to help.

Thanks.

 

In looking at the ESRL reanalysis, though, it looks like the coldest air in the lower 48 during the 1968-69 blast(s) was located in Central Montana, at least from 500mb to 950mb.

[Deweydog]

That cold wave actually produced highs around -25 and lows around -40 in MT and WY. The coldest air still went east of the divide...

 

Well, the coldest air will always be east of the divide, save for situations where it's a due northerly or northwesterly advection event.  Even in 1968 I'm sure the "core" of the coldest air was over and just east of the Rockies as elevation and the proximity to the Canadian Prairies will always reign supreme.  I just find it hard to believe we can do much better than this from an advection/upper level support standpoint...

 

http://mp1.met.psu.edu/~fxg1/NARR/1989/us0203.php

[wx_statman]

Thanks.

In looking at the ESRL reanalysis, though, it looks like the coldest air in the lower 48 during the 1968-69 blast(s) was located in Central Montana, at least from 500mb to 950mb.

I haven't seen the ESRL reanalysis, so I will take your word for it. Even if the column was slightly colder east of the divide, it was pretty close to what spilled over west of the divide. I'm not aware of any surface obs east of the divide colder than the -27/-50 in Eureka, for example. It was an extraordinary event. About as close as we've ever come to having the Rockies "not matter" so to speak.

[wx_statman]

Well, the coldest air will always be east of the divide, save for situations where it's a due northerly or northwesterly advection event.  Even in 1968 I'm sure the "core" of the coldest air was over and just east of the Rockies as elevation and the proximity to the Canadian Prairies will always reign supreme.  I just find it hard to believe we can do much better than this from an advection/upper level support standpoint...

 

http://mp1.met.psu.edu/~fxg1/NARR/1989/us0203.php

From an advection point of view I agree. February 1989 was the king.

[SilverFallsAndrew]

 

Well, the coldest air will always be east of the divide, save for situations where it's a due northerly or northwesterly advection event.  Even in 1968 I'm sure the "core" of the coldest air was over and just east of the Rockies as elevation and the proximity to the Canadian Prairies will always reign supreme.  I just find it hard to believe we can do much better than this from an advection/upper level support standpoint...

 

http://mp1.met.psu.edu/~fxg1/NARR/1989/us0203.php

 

 

This looks like one of those fantasy CFS runs.

[Front Ranger]

I see something that resembles a SW Atlantic ridge going up in response to the deep North American trough, but I wouldn't call it a SE ridge..the weeklies have a -NAO/-AO/-PNA going..looks a lot like hybrid of 1968-69 and 1978-79..

 

The big western cold is coming, but not until around/after New Years, IMO..and even then, I still think it'll be a coast-to-coast deal..

 

Sounds like you're moving up the timing considerably. Last week, you were emphasizing more towards mid January for the West.

 

Hey, either way, if it happens we'll all be happy!

[Front Ranger]

Thanks.

 

In looking at the ESRL reanalysis, though, it looks like the coldest air in the lower 48 during the 1968-69 blast(s) was located in Central Montana, at least from 500mb to 950mb.

 

He was referring specifically to the blast at the end of December 1968. Not the one later in January.

[Phil]

Sounds like you're moving up the timing considerably. Last week, you were emphasizing more towards mid January for the West.

 

Hey, either way, if it happens we'll all be happy!

Nope, I've made no changes to my thinking since October..read my winter outlook if you have any confusions

[Phil]

He was referring specifically to the blast at the end of December 1968. Not the one later in January.

Yep

 

http://catchmypicture.com/QVnvZ7.jpg

[wx_statman]

Yep http://catchmypicture.com/QVnvZ7.jpg

Can't tell much from that, to be honest with you. The cold wave in late January 1969 was definitely centered over MT. There were surface readings into the -50's on the prairies, including at Havre. But the late December blast was a different animal.

[Phil]

Can't tell much from that, to be honest with you. The cold wave in late January 1969 was definitely centered over MT. There were surface readings into the -50's on the prairies, including at Havre. But the late December blast was a different animal.

Understood.

 

As I mentioned before, I look at these things from a macroscale standpoint..you generally almost always see these airmasses max out and slide SE along/east of the mountains as angular momentum is conserved. The mesoscale stuff is mostly out of my league.

[Bryant]

I feel like the North interior is due for a winter blast. There is definitely some bias at play here... but the continuous cold and dry events become very repetitive without some snow along with it. Unfortunately, the North interior scoring usually comes at a cost of anyone south of Seattle receiving rain.

[Front Ranger]

Nope, I've made no changes to my thinking since October..read my winter outlook if you have any confusions

 

I know what your winter outlook said. But you've definitely made comments in the past week indicating you were leaning away from the New Year and closer to mid January for the Western blast.

 

No worries, you gave yourself originally a wide enough window of late Dec to mid Jan, and yes, your comments have always fit somewhere in that window.

[bainbridgekid]

Christmas looks chilly on the Euro.

 

http://download.ecmwf.org/data/web248/get_legacy_plot-web248-20141216065747-15410-0737.gif

[Parksvillewx]

00z Euro is nice. Looks primed for some big cold to slide down towards the end.

[Parksvillewx]

[Front Ranger]

00z Euro is nice. Looks primed for some cold to slide down towards the end.

 

As soon as it showed the Pacific energy digging further west north of HI, I knew this run would be an improvement. 

 

And it's definitely acting like it wants to pop some sort of SE ridge there at the end. Though as we all know, that's impossible this winter.

[Snow]

[Kayla]

I suppose I shouldn't be surprised how much the different the GFS and parallel GFS is compared to the ECMWF as of late, but I'm still surprised. And here I thought the "upgraded" GFS would be better at seeing these large scale pattern changes...silly me.