December Weather In the PNW

[Brian_in_Leavenworth]

I feel like what the 18z GFS ensemble shows is almost exactly the progression that Phil has been describing for weeks now. The GFS show that the block builds a little further to west over Christmas week then everything retrogrades once again with finally the PNW getting hit with some real cold around the 28th-30th.

 

It's really been quite the slow process but it really does look like things are getting close! I'm still really quite amazed that I we look to hold onto this blocking pattern for at least another ~4 weeks.

Here is the 48 hour trend.  48 hours ago the GFS ensemble had the ridge parked right over us.  

 

[Jesse]

Just shy of 50 here this afternoon. That’s about a +7F for the high.

That warmup is going to hit hard when it comes.

[Kayla]

Wow...the Euro weeklies look incredible. 

[Jesse]

18z ensembles are improved.

[Kayla]

Here is the control run for New Years Eve... The mean is also very cold beginning around the 28th.

 

http://models.weatherbell.com/eps/2017121100/noram/eps_m_z500a_c_noram_43.png

[Kayla]

And the mean on the same date...

 

http://models.weatherbell.com/eps/2017121100/noram/eps_m_z500a_noram_43.png

 

[Phil]

Weeks 1-6 on the latest EPS weeklies.

 

Huge flip right around New Years. Solid retrogression signal there, though hopefully we can break down the stratospheric PV and avoid a +EPO.

 

 

 

 

 

 

[Jesse]

I see jesse is on his morals police kick again.

Looks like your shift just started. Keep an eye on that Jesse guy while I’m gone. I got a tip that there may be proof of his moral deviancy in his underwear drawer.

[Front Ranger]

Been about 11 months.

 

Arctic or modified arctic air is a bit different...

 

How's this: when was the last Dec or Jan period that featured temps this warm (highs mainly in the 40s to 50s), with sunshine, for this long?

[Phil]

What "phases" are those?

I think of phases 2-3 as IO, and 4-7 as Indo-Pacific, but it’s kinda debatable.

[Front Ranger]

I feel like what the 18z GFS ensemble shows is almost exactly the progression that Phil has been describing for weeks now. The GFS show that the block builds a little further to west over Christmas week then everything retrogrades once again with finally the PNW getting hit with some real cold around the 28th-30th.

 

It's been quite the slow process but it really does look like things are getting close! I'm still really quite amazed that we look to hold onto this blocking pattern for at least another ~4 weeks.

 

To be fair, he's hardly been the only one saying for weeks that the action probably won't start until late December at the earliest.

[Deweydog]

Arctic or modified arctic air is a bit different...

 

How's this: when was the last Dec or Jan period that featured temps this warm (highs mainly in the 40s to 50s), with sunshine, for this long?

December 2005.

[Geos]

My. Agung is starting to get interesting. I think it’s now erupted 17 times over the last week, with the eruptions progressively intensifying along with a continued “swelling” of the south face of the mountain.

 

This is (presumably) similar to what happened during the 1843 eruption which started with smallish eruptions and continued for about a month until it produced a VEI5 blast.

 

The 1963 eruption also started small, but it was also a bit different in that before it became explosive (VEI4) it produced a lava flow that traveled 7km down the face of the mountain over a 4 week period, then went explosive in the following months.

 

That's an ominous sign that gases are building up inside. They could all be released in one large eruption. Sounds like this volcano is just warming up for its next act.

[Jesse]

December 2005.

Worst. Analog. Ever.

[Karl Bonner]

Wow...the Euro weeklies look incredible. 

Care to give us a peek?

[umadbro]

It just keeps getting pushed back a day at a time...

[Kayla]

To be fair, he's hardly been the only one saying for weeks that the action probably won't start until late December.

 

This is true but Phil has held steadfast on the pattern progression (ridge to discontinuous retrogression) for quite sometime now. Who else has said a blocking pattern would hold itself for possibly 6+ weeks in the PNW? 

[Phil]

It just keeps getting pushed back a day at a time...

No, it doesn’t.

 

Unless you were expecting a blast by Christmas (which was always fairly unlikely in my opinion), I think the progression is going as anticipated. At least for the time being.

[Phil]

This is true but Phil has held steadfast on the pattern progression (ridge to discontinuous retrogression) for quite sometime now. Who else has said a blocking pattern would hold itself for possibly 6+ weeks in the PNW?

Thank you (knocks on wood]. I’m trying very hard to get this one right, haha.

 

Hopefully Mother Nature doesn’t fumble it at the end zone this time. The pieces are all present and in place.

[Deweydog]

Thank you (knocks on wood]. I’m trying very hard to get this one right, haha.

 

Hopefully Mother Nature doesn’t fumble it in the end zone this time. The pieces are all present and in place.

Fumbling in the end zone is a touchdown.

[Phil]

Fumbling in the end zone is a touchdown.

I hate you.

[Front Ranger]

December 2005.

 

I do remember that...just wasn't sure if there'd been a similar period since then.

 

Basically, it doesn't happen all that often. 

[Deweydog]

I hate you.

Maybe we'll just screw up spiking the ball; blow out our shoulder or have the ball shoot off to the side and scratch the cornea of a small child.

[SilverFallsAndrew]

Some big time ensemble spread there. 

[Front Ranger]

This is true but Phil has held steadfast on the pattern progression (ridge to discontinuous retrogression) for quite sometime now. Who else has said a blocking pattern would hold itself for possibly 6+ weeks in the PNW? 

 

Many of the primary analogs discussed had a lengthy +PNA stretch in the late Nov - mid December period. What defines a "blocking pattern" in the PNW? A ridge over or near the PNW? And if the pattern is discontinuous retrogression, wouldn't that allow for the blocking to breakdown at times?

[Karl Bonner]

18z GEFS for The Dalles shows at least four members dipping to -15C, and several more flirt with -10 at one point or another (mean goes as low as -6 just before Christmas!)

 

http://weathertogether.net/models/GFS_ENSEMBLE_1.00_DEGREE/20171211/18z/KDLS_850hPaTemp.png

[umadbro]

Looks like your shift just started. Keep an eye on that Jesse guy while I’m gone. I got a tip that there may be proof of his moral deviancy in his underwear drawer.

Good point or something like that.

[Deweydog]

Many of the primary analogs discussed had a lengthy +PNA stretch in the late Nov - mid December period. What defines a "blocking pattern" in the PNW? A ridge over or near the PNW? And if the pattern is discontinuous retrogression, wouldn't that allow for the blocking to breakdown at times?

You've done a super job too! I've sent around a hallmark card for everyone to sign and express their appreciation of your stable of analogs. Keep checking the mail!

[Deweydog]

And for future reference:

 

https://www.google.com/url?sa=t&source=web&rct=j&url=http://www.dictionary.com/browse/discontinuous&ved=0ahUKEwiv4NexnIPYAhVF22MKHVgpBsYQFghOMAI&usg=AOvVaw12sV-bh9sGNMNXndRHaxjE

[Gradient Keeper]

18z GFS ensemble is actually pretty good FWIW. Block is a tad too close to the coast but still quite chilly with a strong Northerly flow. Very amplified pattern in the long term. 

 

Not too bad and if it tilts ---> We'll be good. Southeast US ridge is pretty nice too. Ensembles for Yakima shows a chilly air mass and possibly modified arctic air which will likely be pulled westward via Gorge into PDX.

[Front Ranger]

You've done a super job too! I've sent around a hallmark card for everyone to sign and express their appreciation of your stable of analogs. Keep checking the mail!

 

Thanks, buddy!

 

Perception is a funny thing...

[Front Ranger]

Not too bad and if it tilts ---> We'll be good. Southeast US ridge is pretty nice too. Ensembles for Yakima shows a chilly air mass and possibly modified arctic air which will likely be pulled westward via Gorge into PDX.

 

Yeah, that's another big change in the ensembles over the past day or so.

[ShawniganLake]

That warmup is going to hit hard when it comes.

I’m ready. Just put a new set of winter tires on my truck today.

[Phil]

Many of the primary analogs discussed had a lengthy +PNA stretch in the late Nov - mid December period. What defines a "blocking pattern" in the PNW? A ridge over or near the PNW? And if the pattern is discontinuous retrogression, wouldn't that allow for the blocking to breakdown at times?

[Geos]

Here is the 48 hour trend.  48 hours ago the GFS ensemble had the ridge parked right over us.  

 

trend.png

 

Definitely some positive progress there. 

We need it to tilt toward the Yukon a bit more.

[Gradient Keeper]

Who's ready for improved/colder 00z runs tonight?

 

Next up..........

*00z GFS in 2 hours 24 minutes (7:24 PM)
00z CMC(Canadian) in 3 hours 9 minutes (8:09 PM)
00z ECMWF in 4 hours 45 minutes (9:45 PM)
Think Cold and SNOW!!!! ❄❄☃❄❄

[Jesse]

I do remember that...just wasn't sure if there'd been a similar period since then.

 

Basically, it doesn't happen all that often. 

 

December 2011 would also fit the bill.

[Brian_in_Leavenworth]

Here is the control run for New Years Eve... The mean is also very cold beginning around the 28th.

 

http://models.weatherbell.com/eps/2017121100/noram/eps_m_z500a_c_noram_43.png

Same hour from last night's 0Z CFS (don't want to show the 12Z)

 

 

 

[Front Ranger]

 

We're in this one together, my friend. In sync on the general pattern progression, and have been since some point in November (we both know that isn't always the case). If this winter doesn't deliver by January, we both go down with the ship. And nothing past mid December has verified yet. 

 

I'm just trying to figure out what Kayla meant by "a blocking pattern holding itself for 6+ weeks in the PNW"? Persistent +PNA transitioning to -PNA sometime after Christmas...discontinuous retrogression of west coast ridge....many times the things discussed on here come down to different terminology, ultimately leading to similar outcomes.

[Front Ranger]

December 2011 would also fit the bill.

 

I believe that ridge was significantly cooler at the surface in many areas.

 

SEA, for example, didn't see a high above 43 from the 1-14th. This month, almost every high at SEA has been warmer than that, with a couple in the 50s.

 

Same holds true for PDX. In Dec 2011, no highs above 44 from the 1-15th. This month has seen 4 highs in the 50s and every day until today has been 45+. Also looks like there was more low clouds/fog in 2011.

 

So while there are some similarities, I'd say that ridge was easily more inversiony at the surface than this one.