December Weather In the PNW

[BLI snowman]

Discuss the ridgy month to come here!

[Deweydog]

Discuss the retrogressive month to come here!

Fixed.

[SilverFallsAndrew]

Why is December always our best month.

[SilverFallsAndrew]

Mark Nelsen just predicted no snow in December. 

[Jesse]

Mark Nelsen just predicted no snow in December.

You get so annoying this time of year.

[Front Ranger]

If Jesse is annoyed, you've really crossed the line.

[Gradient Keeper]

I only saw Mark say ridging through week 2. East winds for at least a week!

 

6z GFS in 45 minutes

[SilverFallsAndrew]

Looking over Silver Falls weather data. They recorded 38" of snow last winter. Snow data can be pretty spotty from that station, but they did a pretty decent job last year. The only notable snowfall they missed was the one in late February. I got about 9" total from that and driving through the park that Sunday they definitely had a few inches on the ground with more to come. That was a very elevation dependent event and they are lower than me, but I bet they got at least 5-6" from it over a couple days. Add that in and they would have about 43" on the year as opposed to my 49.2" (My signature is off by 2" I just haven't fixed it...). 

 

One event they did incredibly well with was the Dec 31-Jan 3rd period. They picked up 14" in that time and reached a max depth of 13". Only 7.3" here with that event and 6" max depth. Just a difference in where the snow showers trained over that period, we had a lot go just south into the park on the 2nd and 3rd...

[Phil]

I agree with the gist of Mark Nelsen's prediction. The final few days of December might throw a wrench in it, though.

[TigerWoodsLibido]

I agree with the gist of Mark Nelsen's prediction. The final few days of December might throw a wrench in it, though.

Final few like final 8 days?

[MikeInEverett]

Block is much different on the 06z. Stronger and in better position.

 

Edit: Ouch, undercut

[SilverFallsAndrew]

Some backdoor cold on the 06z and then everything resets as the westerlies break through. That is one major cold wave for the country.

[Gradient Keeper]

12/1/17 6z GFS 500mb Composite Analogs

 

Day 6-10, 8-14

Very nice improvement

 

Day 8-14  - The positive anomaly is forecast to retrograde to roughly 150 W with an incredibly amplified block anchored over south central Alaska. This would give southern Alaska very high 500mb heights. If the block were to tilt any we would see a major blast. In this configuration we'd likely see modified arctic air into eastern Washington/Columbia Basin. I would be more confident if we had a ridge over the southeast/midwest. Some cold years showing up! 12z GFS in 3 hours 31 minutes!

 

http://www.cpc.ncep.noaa.gov/products/predictions/short_range/tools/gifs/500hgt_comp_06gfs610.gif

 

http://www.cpc.ncep.noaa.gov/products/predictions/short_range/tools/gifs/500hgt_comp_06gfs814.gif

[ShawniganLake]

Just looking through the data for November and I guess we are due for a dry break in the weather. 21 consecutive days with measurable rainfall here. And looking at other SW BC stations, seems like most are in the 21-24 day range.

[Jesse]

If Jesse is annoyed, you've really crossed the line.

I just got off the phone with Bruce Sussman and he says it isn’t going to snow again in the Denver area until April of 2019.

 

You heard it hear first!

[Jesse]

Looking over Silver Falls weather data. They recorded 38" of snow last winter. Snow data can be pretty spotty from that station, but they did a pretty decent job last year. The only notable snowfall they missed was the one in late February. I got about 9" total from that and driving through the park that Sunday they definitely had a few inches on the ground with more to come. That was a very elevation dependent event and they are lower than me, but I bet they got at least 5-6" from it over a couple days. Add that in and they would have about 43" on the year as opposed to my 49.2" (My signature is off by 2" I just haven't fixed it...). 

 

One event they did incredibly well with was the Dec 31-Jan 3rd period. They picked up 14" in that time and reached a max depth of 13". Only 7.3" here with that event and 6" max depth. Just a difference in where the snow showers trained over that period, we had a lot go just south into the park on the 2nd and 3rd...

tldr.

[TT-SEA]

38 here with a nice sunrise on the way.   

 

SEA ended up at +1.3 for November with 8.63 inches of rain (2+ inches above normal).    SEA is also 10.30 inches above normal for the year of 2017.

[TT-SEA]

The block later next week on the 12Z GFS looks much weaker than the runs yesterday.   More in line with the ECMWF.    

 

[Kayla]

The block later next week on the 12Z GFS looks much weaker than the runs yesterday.   More in line with the ECMWF.    

 

The ridge late next week is also getting shoved further west and tilting in the last few runs as well.

[BLI snowman]

Midmonth torch?

[SilverFallsAndrew]

I have a feeling we are going to see a lot more ensembles shoving those westerlies through in the long range. 

[Brian_in_Leavenworth]

Ventrice did say there could be a lot of volatility in the models during the 11-15 day period due to a storm in the West Pacific.

[SilverFallsAndrew]

Ventrice did say there could be a lot of volatility in the models during the 11-15 day period due to a storm in the West Pacific.

 

I remember you posting that. Would make sense. Also would not surprise me if the point of ridging gets watered down a bit per climo. 

[BLI snowman]

I have a feeling we are going to see a lot more ensembles shoving those westerlies through in the long range. 

 

Yeah, pretty tough to avoid at least a week or so of westerly action in December. The block will be undercut and the Midwest will get to thaw.

[TT-SEA]

A little sun to start off December here this morning... hopefully a sign of a more pleasant month ahead.   

 

[van city]

Where's Rob, I need my play by play?

[Jesse]

12z Euro basically keeps us under a ridge through day 10. Definitely lower amplitude than some earlier runs, though.

 

I can’t help but wonder if some lowland locations mix out and get pretty warm next week. To me this isn’t looking like the best low level cold setup, with a warm front brushing us Monday/Tuesday.

[TT-SEA]

12z Euro basically keeps us under a ridge through day 10. Definitely lower amplitude than some earlier runs, though.

 

I can’t help but wonder if some lowland locations mix out and get pretty warm next week. To me this isn’t looking like the best low level cold setup, with a warm front brushing us Monday/Tuesday.

 

 

It will likely get more and more stagnant as the week goes on... in true winter inversion fashion.

[wx_statman]

tldr.

 

True love doesn't run. Amen to that. 

[Phil]

In the climate department, we have an incredible latent heat release event ongoing now. Probably the strongest event since January 2013, from a subseasonal standpoint, and it's partially responsible for the upcoming period of wave amplification over the NPAC.

 

Under the antecedent -NAM, when the tropical wavenumber transitioned into a mode of constructive spatial interference approximately one week ago, convection strengthened markedly over the WPAC/IPWP, which extracted a massive load of heat from the Pacific ocean, releasing it into the middle/upper troposphere (condensation and crystallization releases latent heat).

 

This event has already dropped the global SSTA anomaly by at least 0.1C in just 5 days, and given the -NAM, which represents poleward transfer of heat/mass aloft in the NH, an anomalously large portion of this heat was sent into the NH extratropics, where it's now being emitted to space, as is reflected by the 1.4W/m^2 increase in the TOA OLR anomaly since Nov 18th.

[Jesse]

[Phil]

This latent heat release peaks on December 4th, before it starts to deplete, at which point the subtropics and middle latitudes will start cooling once again, while the equatorward wavetrain strengthens and destabilizes the integral of static stability in the tropics, restarting the cycle.

[Front Ranger]

Ridge appears to be retrograding the wrong way.

[MossMan]

A little sun to start off December here this morning... hopefully a sign of a more pleasant month ahead.

 

Wet and cold up here...ugly.

[TT-SEA]

Wet and cold up here...ugly.

 

Still sunny... but rain is getting closer.  

[MossMan]

Ridge appears to be retrograding the wrong way.

I think we have to put all of our hopes and dreams on Phil’s shoulders and hope he’s spot on about January!

[MossMan]

Having a family day up in La Connor...I cannot wait for a dry day. Ugly.

[Front Ranger]

I think we have to put all of our hopes and dreams on Phil’s shoulders and hope he’s spot on about January!

But he's predicting a slow ridge retrograde this month...

 

And he's one of several going with a cold January.

[Jesse]

Having a family day up in La Connor...I cannot wait for a dry day. Ugly.

I just don’t get how someone could live here their whole lives and be emotionally upset about normal cold and wet winter days. I mean it’s such a huge part of our average winter climate, being bothered by it just seems silly. Tim’s a transplant so it’s more understandable with him.

[MossMan]

I just don’t get how someone could live here their whole lives and be emotionally upset about normal cold and wet winter days. I mean it’s such a huge part of our average winter climate, being bothered by it just seems silly. Tim’s a transplant so it’s more understandable with him.

41yrs of being wet and cold! I’m fine with a wet soggy November but it’s now December and I’m ready to dry off a bit!