December 2016 Observations and Model Discussion for the Pacific Northwest

[Chewbacca Defense]

How does the set up look for Whatcom County this weekend?  I have relatives coming in tomorrow and flying back out on Sunday.  They will have kittens if they are not able to fly out on Sunday....

 

 

Anyway, I was trying to figure out if this is a scenario like last weekend where the cold air got scoured out everywhere except Whatcom and points north....

[crf450ish]

Got down to -18 at my cabin lastnight! cold airmass.

Wait till Saturday morning around 6ish am or so. Might be close to 25 below...

[SilverFallsAndrew]

Couple pics from my Dad's house near Silverton yesterday.

 

[BLI snowman]

Going to end up as their most impressive cold stretch since Dec 2008. And 2008 was their most impressive cold stretch in a long time, as far as duration goes.

 

Definitely feels reminiscent of 1992-93 so far.

[Front Ranger]

Surprised no one has mentioned the NAM. It shows a decent snow event for lower BC and north of Seattle on Sat night/Sun.

 

[HighlandExperience]

Surprised no one has mentioned the NAM. It shows a decent snow event for lower BC and north of Seattle on Sat night/Sun.

 

get_orig_img.gif

Of course king county gets left out mostly

[TT-SEA]

12Z ECMWF shows some lowland snow on Christmas morning as a system is moving in... hard to tell if it would transition quickly since day 10 runs out through 4 a.m. on Christmas.  

 

The control run of the ECMWF ensemble is wonderful for Christmas weekend with a storm digging into CA and cold air across the PNW.   Not sure about any precip on that run.

 

The ensemble mean basically agrees with the operational run at day 10.

[TT-SEA]

The EPS mean and control run both show a cold west and a warm east on Christmas weekend.

[Front Ranger]

Definitely feels reminiscent of 1992-93 so far.

 

Yeah, although Dec 1992 was much milder up there than this month has been, until the last week of the month. More Fraser outflow this winter so far.

 

I would say it feels at least as much like 1984-85, 1970-71, or 1961-62.

[HighlandExperience]

[SilverFallsAndrew]

Really nice low level cold in place in the Columbia basin, Central Oregon, and the Willamette Valley. Air aloft will be cooling quite a bit over the next 1-2 days, but not all that cold at present. Horse Creek at 3400' in the Western Cascades is sitting at 32, Santiam Junction 31.

[Jesse]

The mid-Willamette valley could see some pretty cold temps the next few mornings.

[luvssnow_spokane]

Surprised no one has mentioned the NAM. It shows a decent snow event for lower BC and north of Seattle on Sat night/Sun.

 

get_orig_img.gif

Because nobody likes them.

[SilverFallsAndrew]

The EPS mean and control run both show a cold west and a warm east on Christmas weekend.

 

The way it should be. 

[SilverFallsAndrew]

The mid-Willamette valley could see some pretty cold temps the next few mornings.

 

If there is decent clearing. From what have heard there is considerable low cloudiness today.

[Jesse]

If there is decent clearing. From what have heard there is considerable low cloudiness today.

 

Keeping temps nice and low for now. But clearing looks to be inching in from the NW. Increasing offshore flow could also help dry the mid-levels.

 

I bet SLE hits 15 at some point the next two mornings.

[Bryant]

Surprised no one has mentioned the NAM. It shows a decent snow event for lower BC and north of Seattle on Sat night/Sun.

 

 

 

Going to be a close call. Cold air will be in place, but the trajectory of the system isn't favorable to keep the cold air around long. 

[SilverFallsAndrew]

Keeping temps nice and low for now. But clearing looks to be inching in from the NW. Increasing offshore flow could also help dry the mid-levels.

 

I bet SLE hits 15 at some point the next two mornings.

 

If they get good clearing than probably. They don't get as good of radiational cooling as they used to...I am not entirely sure why. Some UHI, but idk if that is all of it. I have sometimes wondered if they moved their sensor...

[Front Ranger]

The GFS and GEM ensembles both have a coherent and fairly impressive signal for more NE Pacific blocking the final week of December.

 

 

[Front Ranger]

Keeping temps nice and low for now. But clearing looks to be inching in from the NW. Increasing offshore flow could also help dry the mid-levels.

 

I bet SLE hits 15 at some point the next two mornings.

 

I expect big things out of HIO.

[bainbridgekid]

If they get good clearing than probably. They don't get as good of radiational cooling as they used to...I am not entirely sure why. Some UHI, but idk if that is all of it. I have sometimes wondered if they moved their sensor...

I think that probably happens more than you'd think.

 

Even a move of a couple hundred feet can make a significant difference to long term averages if the amount of concrete around the sensor changes. Kind of frustrating.

[Phil]

The EPS mean and control run both show a cold west and a warm east on Christmas weekend.

Predictable. Will be the sixth consecutive blowtorch Christmas here. This coming right after the consecutive horror shows in 2014 and 2015.

[Canadian guy]

Looks like a good signal for a southeast ridge too.

[Bryant]

WRF says maybe...

 

http://i.imgur.com/Z5kUzxb.jpg

[SilverFallsAndrew]

The GFS and GEM ensembles both have a coherent and fairly impressive signal for more NE Pacific blocking the final week of December.

 

gfsens.gif

 

gemens.gif

 

The pre-Christmas trough has some potential too, but even if it fails to deliver we will have more chances coming up...

[MossMan]

Yeah, although Dec 1992 was much milder up there than this month has been, until the last week of the month. More Fraser outflow this winter so far.

 

I would say it feels at least as much like 1984-85, 1970-71, or 1961-62.

How about 1949/50...been hearing the progression has been similar?

[Front Ranger]

I think that probably happens more than you'd think.

 

Even a move of a couple hundred feet can make a significant difference to long term averages if the amount of concrete around the sensor changes. Kind of frustrating.

 

Yep. Also: vegetation changes, proximity to water, proximity to lighting...so many things can have small, but in the long term significant effects on readings.

[Bryant]

Predictable. Will be the sixth consecutive blowtorch Christmas here. This coming right after the consecutive horror shows in 2014 and 2015.

 

check your messenger

[SilverFallsAndrew]

I think that probably happens more than you'd think.

 

Even a move of a couple hundred feet can make a significant difference to long term averages if the amount of concrete around the sensor changes. Kind of frustrating.

 

Knowing that area, if they moved it from the south end of the airport to the northwest end it would make a difference. 

 

Another thing about SLE. Records go back to 1892, obviously there was no airport then. No one has ever been able to tell me where the observations were taken in Salem before the actual airport opened...Was it in that exact location? I find that unlikely as back then that would have been outside of town. 

[Jesse]

If they get good clearing than probably. They don't get as good of radiational cooling as they used to...I am not entirely sure why. Some UHI, but idk if that is all of it. I have sometimes wondered if they moved their sensor...

Some clearing is pretty likely later today through early Saturday. The solid snowcover down there should give them a pretty big assist as well.

[Front Ranger]

The pre-Christmas trough has some potential too, but even if it fails to deliver we will have more chances coming up...

 

Definitely. Euro ensembles are on board for Christmas weekend possibilities as well. 

 

I know there are still quite a few people on here wishing they'd had more snow to this point, and that's understandable. But the reality is we're looking at a rather cold first half of December that brought multiple rounds of cold and lowland snow, with more cold and probably some lowland snow within 72 hours, and beyond that looks promising as well.

 

Could be a lot worse.

[Phil]

Yeah, although Dec 1992 was much milder up there than this month has been, until the last week of the month. More Fraser outflow this winter so far.

 

I would say it feels at least as much like 1984-85, 1970-71, or 1961-62.

I've been experimenting with dozens of analog compilations over the autumn, and thus far, this one has verified the strongest in terms of the 500mb departure over the NHEM. The NPAC is by far the best match on this compilation, though still imperfect.

 

Here's what these -ENSO analogs predicted for O/N/D. Obviously, the October -AO was unprecedented and without match in any -ENSO year.

 

http://i724.photobucket.com/albums/ww243/phillywillie/Mobile%20Uploads/3FC31C02-9706-4451-A43D-3117477AA97F_zpstv7zw4ut.png

 

http://i724.photobucket.com/albums/ww243/phillywillie/Mobile%20Uploads/475DB62C-EC17-4855-841D-E203C105DFC2_zpsp84qkonj.png

 

http://i724.photobucket.com/albums/ww243/phillywillie/Mobile%20Uploads/C8471ECB-614F-4D64-9043-B446C09D229D_zpsjer0me9x.png

[Jesse]

I think that probably happens more than you'd think.

 

Even a move of a couple hundred feet can make a significant difference to long term averages if the amount of concrete around the sensor changes. Kind of frustrating.

The annoying this is that 90% of these types of changes make things read warmer, not cooler.

 

Kind of frustrating and adds a complex wrinkle into parsing out warming from climate change and land use changes. Makes it difficult to get as clear a signal.

[Phil]

How about 1949/50...been hearing the progression has been similar?

I don't think that's a very good match overall. A few intraseasonal alignments but no similarities w/ the background states.

[Jesse]

I expect big things out of HIO.

There should be a lot of teens popping up around NW Oregon/SW Washington. Maybe lower in spots.

[Phil]

The way it should be.

I know who I'll be trolling in 5 weeks.

[Front Ranger]

How about 1949/50...been hearing the progression has been similar?

 

Ha, well you know the dangers of bringing that one up. But yes, in terms of observed weather in the PNW especially going back through November, 1949 is certainly a pretty close match. But there is a real possibility this December ends up colder, perhaps much colder, than that one for much of the PNW.

 

Dec 1948 might actually end up a better match.

[SilverFallsAndrew]

Ha, well you know the dangers of bringing that one up. But yes, in terms of observed weather in the PNW especially going back through November, 1949 is certainly a pretty close match. But there is a real possibility this December ends up colder, perhaps much colder, than that one for much of the PNW.

 

Dec 1948 might actually end up a better match.

 

January 1949 is underrated imo...Its in my top 5 months I wish I had experienced... Jan 1950, Jan 1930, Jan 1969, Jan 1949, Dec 1919.

[Kayla]

12z EPS mean is showing 31/17 day at PDX on Saturday. Pretty impressive. It usually does pretty well with temps so Saturday could be PDX's coldest low since 2013 I believe.

[MossMan]

January 1949 is underrated imo...Its in my top 5 months I wish I had experienced... Jan 1950, Jan 1930, Jan 1969, Jan 1949, Dec 1919.

I haven't heard much about Jan. 1949...what was it like?