December 2020 Weather Observations for the PNW

[Brian_in_Leavenworth]

6 minutes ago, Rubus Leucodermis said:

This is probably the best (i.e. snowiest in the lowlands) GFS map I can find, and it’s definitely very marginal. Only shows lowland snow up against the Coast Mountains where precip rates are the highest (and perhaps some cooler air is banked). We shall see.

Here is a higher resolution image from the GFS (from Pivotalweather.com)  This is total snow, as opposed to 24 hour snow.

[Rubus Leucodermis]

4 minutes ago, Brian_in_Leavenworth said:

Here is a higher resolution image from the GFS (from Pivotalweather.com)  This is total snow, as opposed to 24 hour snow.

Basically, that means some wet flakes in the air closer to the BC Coast Mountains than I am. That’s all those lightest shades of gray typically amount to. We shall see.

[TigerWoodsLibido]

EC and GEM don't show any low elevation action so this would seem to be the FV3's cold bias.

[SouthHillFrosty]

1 minute ago, TigerWoodsLibido said:

EC and GEM don't show any low elevation action so this would seem to be the FV3's cold bias.

Probably a cold bias. This show a little snow for Portland tho

[kokaneekidz]

1 minute ago, SouthHillFrosty said:

Probably a cold bias. This show a little snow for Portland tho

Appears to be a 500' snow level event except at the surface near the CDN border. The west hills and Beaverton look to do well.

[MossMan]

51 minutes ago, kokaneekidz said:

I love the self sealing doors on my Legend. Now only Bentleys and million dollar cars have that feature unfortunately. That is a beautiful Berlina Black RSX!!! Those were fast, BUT they should have kept the Integra nameplate like in Japan domestic market.

I did not know about those self sealing doors! Yeah my wife really misses her RSX. Her current vehicle is a 2014 Outback...Not quite as beautiful but it fits kids, dogs, and doesn’t have to sit in the garage when it snows! 

[van city]

The Euro Weeklies are out.

[MossMan]

21 minutes ago, Rubus Leucodermis said:

Hmmm… Actually have some green over me on this one.

I’m in the lightest shade of green!!!

[Brian_in_Leavenworth]

3 minutes ago, van city said:

The Euro Weeklies are out.

Mine goes out to hour 402 or so.  Based only on that, it looks like Ventrice was right.  No big cold for Christmas, more like a continuation of what we are already seeing on the EPS.  Do you have any more info beyond that?

[Rubus Leucodermis]

6 minutes ago, MossMan said:

I’m in the lightest shade of green!!!

I’m in the 2nd lightest, so suck it! It’s gonna be epic! Maybe a whole ¼" skiff of slush!

[SouthHillFrosty]

2 minutes ago, Rubus Leucodermis said:

I’m in the 2nd lightest, so suck it! It’s gonna be epic! Maybe a whole ¼" skiff of slush!

That is about what I got all of last year!!

[ShawniganLake]

45 minutes ago, TT-SEA said:

 

12Z ECMWF does not show much lowland snow... not even for my area.   I am not sure what the NWS is seeing but we know the GFS snowfall maps can be goofy.

 

 

The gfs had been steady in showing some snow potential up this way in the mid range.  Of course that model seems to really like overdoing cold in that range, especially since the update. We saw it numerous times last winter as well. 

[Brian_in_Leavenworth]

Just saw the snowfall matrix for my area.  Looks similar to the previous run as far as the amount of snow.  What is noticeable is that the range of all the individual members was a lot smaller, so must be better agreement.   Fewer outliers.

[Brian_in_Leavenworth]

8 minutes ago, hawkstwelve said:

While the latest ECMWF weeklies don't look as nice for the time period around Christmas they do look quite, quite good come January and continuing through to mid/end of January. Some pretty strong signals in there.

Not terribly surprising that the pattern change/GOA blocking has been pushed back a little bit. Seems to be a common theme for models to jump to that regime too quickly.

Edited to include the now-controversial 850mb temp anomaly map.

Looks like it is trying to get there.  I remember the last weeklies, there was improvement with Christmas week, but not quite as good following.  This one might be closer to the one that was run last Monday.

[Phil]

29 minutes ago, Brian_in_Leavenworth said:

Mine goes out to hour 402 or so.  Based only on that, it looks like Ventrice was right.  No big cold for Christmas, more like a continuation of what we are already seeing on the EPS.  Do you have any more info beyond that?

Noticeably stronger NPAC blocking 2nd week of January onwards. 

[Phil]

1 minute ago, Phil said:

Noticeably stronger NPAC blocking 2nd week of January onwards. 

But the mean also has a more +AO look. Which makes the NPAC blocking all the more important. Really the only game in town, verbatim.

[Gradient Keeper]

Weeklies kind of looking like 2007/2008. Tons of snow above 1000' .... We just need that September-October upper level pattern to return.... I guess this means no point in model riding until January 6th-7th? I started getting the shakes and shivers from withdrawal symptoms as I typed that. Yikes. Then again I've seen the Weeklies fail immensely several times, so who knows. I mean aside from the Gorton's Fisherman, Magic 8-Ball, and Miss Cleo. Who knows.

[Gradient Keeper]

18z GFS 10 Day GIF 500mb Height Anomaly, 10 Day Rainfall, Snowfall totals (Wetter than a poodle in a car wash (c)Rob 2004? Nice mountain snows too.)

[Rubus Leucodermis]

3 minutes ago, DJ Droppin said:

18z GFS 10 Day GIF 500mb Height Anomaly, 10 Day Rainfall, Snowfall totals (Wetter than a poodle in a car wash (c)Rob 2004? Nice mountain snows too.)

Quack!

[Front Ranger]

2 hours ago, Deweydog said:

Yeah, they looked AMAZING yesterday...

 

They were looking better.

[Gradient Keeper]

Any updates on the much anticipated SSW? Mid-December? or has that fallen apart.

[Deweydog]

10 minutes ago, DJ Droppin said:

Any updates on the much anticipated SSW? Mid-December? or has that fallen apart.

The 12z kinda tried but she stayed pretty burly.

[umadbro]

If December is doing to deliver any goodies, I don't see the models showing anything until after the weekend AR. Usually that can "trigger" the models.

[Deweydog]

13 minutes ago, Front Ranger said:

They were looking better.

Depends on perspective.  They still look good for edging toward a more active and progressive period heading toward and beyond mid month.

[Link]

So are you guys sure this isn't an El Nino as it's behaving like one.

[Deweydog]

1 minute ago, Link said:

So are you guys sure this isn't an El Nino as it's behaving like one.

ENSO lag.

[MossMan]

1 minute ago, Deweydog said:

The 12z kinda tried but she stayed pretty burly.

Do you think we are going to have a white any holiday this winter season? 

[Brian_in_Leavenworth]

5 minutes ago, Link said:

So are you guys sure this isn't an El Nino as it's behaving like one.

Once the weather gets active, it won't look like an El Nino.  

[TT-SEA]

3 minutes ago, Brian_in_Leavenworth said:

Once the weather gets active, it won't look like an El Nino.  

 

December of 2015 was about as active as it can get... and that was a strong Nino. 

[Deweydog]

8 minutes ago, MossMan said:

Do you think we are going to have a white any holiday this winter season? 

[weatherwonder]

44 minutes ago, DJ Droppin said:

Any updates on the much anticipated SSW? Mid-December? or has that fallen apart.

SSWIs still on the table , just slightly delayed 

The models are still in flux but will catch on very soon in the next few days!  

[Brian_in_Leavenworth]

24 minutes ago, TT-SEA said:

 

December of 2015 was about as active as it can get... and that was a strong Nino. 

Good point.  I remember  getting a lot of  snow that December.  The Nino  didn't really kick  in until mid January, and then the weather shut down. 

[TigerWoodsLibido]

33 minutes ago, TT-SEA said:

 

December of 2015 was about as active as it can get... and that was a strong Nino. 

Yup, active with a lot of rain and very warm. Was +4.2F on the month. Complete dud of a winter, coldest temp was 17F on Nov 29 lol.

[TT-SEA]

3 minutes ago, TigerWoodsLibido said:

Yup, active with a lot of rain and very warm. Was +4.2F on the month. Complete dud of a winter.

I think the mountains up here had record snowfall that December.   I remember the ski conditions were insane.   

[BLI snowman]

12 minutes ago, Brian_in_Leavenworth said:

Good point.  I remember  getting a lot of  snow that December.  The Nino  didn't really kick  in until mid January, and then the weather shut down. 

That's pretty typical of most ENSO events. The forcing usually starts to really get going around the 2nd or 3rd week of January. The last couple of winters were very unusual in that they were more "back-loaded" Ninos, especially 2018-19, but they were also pretty weak ENSO events.

[Meatyorologist]

 

[Gradient Keeper]

The Op runs that have featured a less progressive NPAC sure want to get blocky quickly similarly to the several extended GEFS and EPS runs. Even a few ensembles runs Day 10-16 have tried to amplify the flat ridge at ~160-145 W. Root for a less progressive pattern and hope a trend ensues. C'MON!!!!

00z GFS in 3 hours 26 minutes

[MossMan]

16 minutes ago, TigerWoodsLibido said:

Yup, active with a lot of rain and very warm. Was +4.2F on the month. Complete dud of a winter, coldest temp was 17F on Nov 29 lol.

I had some slush on the 14th, 24th, and 27th in 2015! We visited Leavenworth at the end of the month and they were loaded with wonderful white stuff!! (Oh and a little more slush on 1/4/16) 

[MossMan]

13 minutes ago, Meatyorologist said:

 

Models having a rough time with a pattern change? 

[Gradient Keeper]

16 minutes ago, Meatyorologist said:

 

A touch of model uncertainty/noise. This tells me big model swings are possible and could be quite abrupt "out of nowhere" too.