December 2020 Weather Observations for the PNW

[Rubus Leucodermis]

2 minutes ago, wxmet said:

Can’t remember of the top of by head, when was the last time the ECMWF failed a snow forecast?

More precisely, when was the last time both the GFS and the Euro failed a snow forecast the day before?

[SouthHillFrosty]

3 minutes ago, wxmet said:

Can’t remember of the top of by head, when was the last time the ECMWF failed a snow forecast?

It had one for 2017. Instead of a couple inches, only had a rain snow mix and I’m close to 500’

[Gradient Keeper]

What did I miss?

00z NAM in 1 hour 26 minutes

[SouthHillFrosty]

1 minute ago, puyallupjon said:

convergence zones rarely set up over Puyallup.  they may set up to the north and move from north to south before petering out though.  something stinks about this set up.  again, it looks like someone's 4 year old got a hold of some gray, blue and pink crayons and just went to town.

Rare but it happens. We had one like 5 years ago in the summer. We are due!!

[wxmet]

53 minutes ago, TT-SEA said:

 

In addition to getting the snowblower ready... we just got the shovels and all the sleds down from the attic above the garage.   We are full winter mode now.   My daughter is done with school now for the holidays so she will be sledding from the Tuesday through Christmas Day.     

Looks the rain holds off until after dark on Christmas and that will probably be when the real melting starts here.

New NWS graphic is showing less than an inch in North Bend. Good luck sledding. I think you can replace the snowblower with a hairdryer.

[Jesse]

11 minutes ago, DJ Droppin said:

What did I miss?

00z NAM in 1 hour 26 minutes

We've stolen Mossman's identity and are about to take his plow on a joyride over Steven's Pass.

[MossMan]

1 minute ago, Jesse said:

We've stolen Mossman's identity and are about to take his plow on a joyride over Steven's Pass.

It does have a full tank so it might make it there! 

[Gradient Keeper]

8 minutes ago, Jesse said:

We've stolen Mossman's identity and are about to take his plow on a joyride over Steven's Pass.

Wow. Finally something productive. Oh, I just saw the EPS. Very good agreement for the SSW to be underway around Day 7. Looks excellent.

00z ECMWF in 5 hours 13 minutes

[Esquimalt]

How does the EPS look for the 18Z?  Much change from the 12Z?  Thanks all. 

[Rubus Leucodermis]

 

[Front Ranger]

36 minutes ago, TacomaWaWx said:

Yea I’d like to see what areas got snow during the 1974 event. Looks like it was central/south sound so maybe it wouldn’t be unprecedented if it occurred tomorrow. I think we’re just too close to the water even at our elevation. Slushy inch of snow is probably the best case scenario in our area. 

Yeah, it was definitely focused from north Seattle down to Olympia. Puyallup got 10"!

Areas north of Everett got little to nothing.

[MossMan]

3 minutes ago, Front Ranger said:

Yeah, it was definitely focused from north Seattle down to Olympia. Puyallup got 10"!

Areas north of Everett got little to nothing.

Ugh...Un-staging my plow now. 

[TheNewCulverJosh]

Nothing matters unless you get those yellow and orange echoes over you.  Green isn't going to do it.  It really is that simple in these setups >1000'

[Front Ranger]

5 minutes ago, MossMan said:

Ugh...Un-staging my plow now. 

Historical events often repeat exactly the same, so yes, I would. 

[SouthHillFrosty]

5 minutes ago, MossMan said:

Ugh...Un-staging my plow now. 

I’ll pay you $500 to plow my street if Puyallup gets 10 inches tomorrow 

[VancouverIslandSouth]

The wind has shifted from SW to NW here with the odd N gust in the mix. Temperature is 46F but the dewpoint has dropped to around 39F from 45F a couple hours ago. The developing low seems to be coming into view in the satellite loop now.

[wxmet]

These 00z runs are going to be critical as a portion of the trough will be sampled by some of the observation sites in western Alaska

 

[OysterPrintout]

Almost a relief from down here to not have to track a real marginal setup. Feels like PDX has busted a lot recently in those scenarios. Rooting for a positive outcome up there, which I will then transition to a forum familiar version of bitterness and jealousy and hyperbolic "it will never snow here again" before the PV lobe splits and crushes us in mid Jan.

[Cloud]

My guess is <0.5” for most folks around the Sound. 

[Gradient Keeper]

8 minutes ago, OysterPrintout said:

Almost a relief from down here to not have to track a real marginal setup. Feels like PDX has busted a lot recently in those scenarios. Rooting for a positive outcome up there, which I will then transition to a forum familiar version of bitterness and jealousy and hyperbolic "it will never snow here again" before the PV lobe splits and crushes us in mid Jan.

I love watching the models when a PV lobe pivots down through Yukon. The mechanical forcing is astounding on the entire pattern.

00z GFS in 2 hours 13 minutes

[Requiem]

9 minutes ago, OysterPrintout said:

Almost a relief from down here to not have to track a real marginal setup. Feels like PDX has busted a lot recently in those scenarios. Rooting for a positive outcome up there, which I will then transition to a forum familiar version of bitterness and jealousy and hyperbolic "it will never snow here again" before the PV lobe splits and crushes us in mid Jan.

March was pretty decent for hilly areas— was nice to have some snow after the January debacle haha 

[OysterPrintout]

1 minute ago, Requiem said:

March was pretty decent for hilly areas— was nice to have some snow after the January debacle haha 

yeah hills tend to do ok in the marginal setups. March I had about 15 minutes of a great snow globe onto wet pavement which has by and large been the modus operandi in the city center since Jan 2017. Some dustings in 2019.

The last event of any real sticking snow was 2/20 2018 which had had 4" at the airport but I got about 1-2" in Goose Hollow 

[MR.SNOWMIZER]

1 hour ago, wxmet said:

Can’t remember of the top of by head, when was the last time the ECMWF failed a snow forecast?

Not that it matters much but it does a horrible job for the area around my cabin. The WRF model does much better. None of them are all that great at predicting snow amounts though. 

[TacomaWaWx]

46 minutes ago, Front Ranger said:

Yeah, it was definitely focused from north Seattle down to Olympia. Puyallup got 10"!

Areas north of Everett got little to nothing.

So from Seattle to Olympia there was a pretty widespread decent snow event in 74. It is 2020 wouldn’t be surprising. 

[GHweatherChris]

Really hoping the models show something interesting soon.

[TheNewCulverJosh]

The difference between 250' and the Hwy 2 trestle will be fun to watch if this is what I think it is. 

[High Desert Mat?]

We’ve lost Jim. But I’m sure he knows more than the Mets at the NWS. 
 

I do want to go back to a question that was asked earlier but had no response. How long does it take the models to respond to an SSW event? And if I can add to it, is it underway already and doesn’t finish up for 16 days or has it yet to begin?

 

Phil? Anyone?

[wxmet]

NAM 00z looks much further north out to 12z on Monday.

[bainbridgekid]

0z NAM stronger and significantly further North.

I don't think exact track matters as much for the Puget Sound area a lot of people think with this though. It is the backwash to the West of the low once it moves into the Cascades that has a chance to bring lowland snow and that won't be too impacted for the Central Sound whether it comes through Tacoma or Everett. Track has a much bigger impact in Victoria/Port Angeles/Bham.

[wxmet]

4 minutes ago, hawkstwelve said:

Yeah no bueno. Hope it goes due E from there. 

Not necessarily bad. Temp profile looks more or less the same but it's also slow than 18z.

[VancouverIslandSouth]

8 minutes ago, wxmet said:

NAM 00z looks much further north out to 12z on Monday.

It's even too far north for Victoria, almost a carbon repeat of Dec 19, 2017:

[wxmet]

Looks late late morning and afternoon the Sound is shadowed. Could be a good thing depending on how you look at it.

[SouthHillFrosty]

4 minutes ago, hawkstwelve said:

Through 7PM...

There is a nice jump up in totals for King County between 4-7PM.

Wow big drop for Bellingham and Tacoma. Wonder if Pierce County gets some after 7pm tho

[bainbridgekid]

The later timing on the NAM caused by the stronger further North low would actually be a good thing for the Sound since the best dynamics would be after sunset.

[Gradient Keeper]

1 minute ago, bainbridgekid said:

The later timing on the NAM caused by the stronger further North low would actually be a good thing for the Sound since the best dynamics would be after sunset.

Yep!

00z EPS (Pivotal) in 6 hours 23 minutes

[TheNewCulverJosh]

Looks like a normal "dynamic cooling" bust.

These pan out about as often as I get carded.  Only hope is a narrow and heavy band.  Clearview will probably do well.  Boeing Freeway,etc... Melts after it passes.

[Gradient Keeper]

2 minutes ago, hawkstwelve said:

Here's the 3km NAM through 7PM. It cut way back on totals for just about everyone compared to 18z.

Pretty much the entire event for King County is between 3-6PM.

What I'd give for just 1.7" of snow. C'MON!!!!

00z ECMWF (Christmas Eve) in 99 hours 34 minutes

[Cloud]

This is such a tease lol  

[wxmet]

NAM caving a bit to the ECMWF. Will the other models follow suite? Stayed tuned.

[SouthHillFrosty]

4 minutes ago, hawkstwelve said:

Here's the 3km NAM through 7PM. It cut way back on totals for just about everyone compared to 18z.

Pretty much the entire event for King County is between 3-6PM.

Wow I went from 4 inches to literally zero. Tough bounce. Look @ Port Angeles. They had there totals REALLY cut back