December 2020 Weather Observations for the PNW

[Meatyorologist]

06z GFS Day 11

[Meatyorologist]

06z GFS Day 12

[Meatyorologist]

06z GFS Day 13

[Meatyorologist]

06z GFS Day 14

[Meatyorologist]

06z GFS Day 15

[Meatyorologist]

06z GFS Day 16

[Meatyorologist]

10 Day Precip/Snowfall

[Meatyorologist]

Boring run that torches near the end. Any naughty children might have their coal ignited under that pattern. Onto the 12z.

[weatherwonder]

8 hours ago, DJ Droppin said:

Go EURO! 00z EPS shows the big pattern change just in time for Christmas! C'MON!!!!

Like I have been saying

it is coming!

 

[weatherwonder]

4 hours ago, Meatyorologist said:

Boring run that torches near the end. Any naughty children might have their coal ignited under that pattern. Onto the 12z.

Patience my friend 

lots of time for change before Christmas
models are still struggling with the upcoming pattern a little 

you may be quite surprised at the outcome around Christmas 

[TT-SEA]

00Z EPS...

 

[MossMan]

Currently 43 and cloudy. 
.01” so far on the day, .62” for the month, and 54.42” for the year. 

[Omegaraptor]

Up at Timberline now. Changed over to snow a little bit above Gov’t Camp, around 4200-4500’.

[SilverFallsAndrew]

4 minutes ago, Omegaraptor said:

Up at Timberline now. Changed over to snow a little bit above Gov’t Camp, around 4200-4500’.

Right on. Was really mild last night but temps have fallen off quite a bit this morning. Down to 36.

[SilverFallsAndrew]

Picked up 0.63" last night. At least these little systems have been overachieving. 

[El_Nina]

0.51" here with the system which brings December to 0.85". 

[Rubus Leucodermis]

In my zone’s forecast:

Quote

.FRIDAY NIGHT...Mostly cloudy with a slight chance of rain in the evening, then partly cloudy with a chance of rain, snow and a slight chance of light freezing rain after midnight. Lows in the lower to mid 30s.

 

[Deweydog]

12z!!!

[SilverFallsAndrew]

12z does away with most of the warm rain for the weekend. Jesse will appreciate that. 

[Rubus Leucodermis]

45 minutes ago, hawkstwelve said:

An odd long term discussion from NWS Seattle this morning. Not really sure what they are seeing to believe there will be wintery precip and/or freezing rain potential Friday night. 

Per 06z Euro, 850s are around -4/-5, 925s are -1, and surface temps are hovering the mid 30s. Not to mention most of the precip is done by 10PM. 

The usually ultra-conservative forecast office is mimicking the weenieness of the office down south apparently. Unless I'm just missing something. 

Perhaps they are applying human knowledge because such model runs have preceded marginal lowland snowfalls in Whatcom County before? My forecast low for Friday night is 34˚F, which is definitely cold enough to support wet snow in the right conditions.

[SilverFallsAndrew]

Overall pretty wet, active, and mild. 

[Rubus Leucodermis]

The logic behind chances of wintry precipitation in some lowland areas Friday night or Saturday morning is pretty explicitly laid out:

Quote

.LONG TERM /SATURDAY THROUGH TUESDAY/...The take home message of the long term is that it is going to be wet. Saturday is going to be the day that we need to be vigilant of. Snow levels are dropping to around 1000 feet, temperatures are at or near freezing in many locations (particularly Whatcom County and South of Olympia). And we have rain on the way. With this there is the potential for a wintery mix of rain and snow in the lowland areas Friday night into Saturday morning. During this time we are also concerned for the possibility of freezing rain. Freezing rain would be most probable in the valleys of Whatcom and Skagit counties, including areas near the water. The other main area of concern for freezing rain is the low laying areas south of Olympia, as low temperatures are below freezing. We are still a few days out and confidence is low for the freezing rain, but due to the possible impacts, the need to include it in the forecast was there. Keep updated on the forecast in the coming days as confidence will grow on if/when/where freezing rain and the wintery mix of precipitation could occur.

It’s been a while, but I have seen this sort of thing (system arrives as just the right time for the result of overnight cooling to permit snow to fall to low elevations, at least at first) happen before. We shall see.

[SilverFallsAndrew]

Here is a WET pattern.

[Rubus Leucodermis]

2 minutes ago, SilverFallsAndrew said:

Here is a WET pattern.

Hopefully a Blob-killer.

[Brian_in_Leavenworth]

15 minutes ago, SilverFallsAndrew said:

Overall pretty wet, active, and mild. 

Very wet indeed.  Tons of mountain snow.  Looks like pretty normal December temps, but torches toward the end.

[Front Ranger]

Significant model disagreement over the Pacific 8 days from now.

[Deweydog]

PDX up to 47.

[luminen]

21 minutes ago, Front Ranger said:

Significant model disagreement over the Pacific 8 days from now.

GFS looks weird but the GEM? I just don't see that panning out.

[SilverFallsAndrew]

AR for Christmas?!

[ShawniganLake]

Maybe some flooding for Christmas!

[rsktkr]

Has there ever been a reverse rug pull in the PNW region?

Meaning models were looking grim/boring but at the last minute everything changed and we wound up with the goods?

We get the rug pulled on cold/snowy weather CONSTANTLY so I would imagine it has happened in reverse but I haven't lived here long enough to have experienced one. 

[SilverFallsAndrew]

1 minute ago, rsktkr said:

Has there ever been a reverse rug pull in the PNW region?

Meaning models were looking grim/boring but at the last minute everything changed and we wound up with the goods?

We get the rug pulled on cold/snowy weather CONSTANTLY so I would imagine it has happened in reverse but I haven't lived here long enough to have experienced one. 

That February 2014 snow event popped up pretty quick on the models. 

[jakerepp]

1 minute ago, rsktkr said:

Has there ever been a reverse rug pull in the PNW region?

Meaning models were looking grim/boring but at the last minute everything changed and we wound up with the goods?

We get the rug pulled on cold/snowy weather CONSTANTLY so I would imagine it has happened in reverse but I haven't lived here long enough to have experienced one. 

Sometimes an unexpected PSCZ will set up and will bring localized heavy rain/snow or even thunder storms. 

I'm sure someone will have a better example of a more widespread pattern that popped up out of nowhere, but that's as much as I can come up with right now.

[jakerepp]

Will the skies be clear enough for anyone to enjoy this?

[FroYoBro]

2 minutes ago, SilverFallsAndrew said:

That February 2014 snow event popped up pretty quick on the models. 

Yeah, that was a pretty big change only 2-3 days out. It was looking very cold and mostly dry. Ended up not as cold, but very snowy here. 

[ShawniganLake]

3 minutes ago, rsktkr said:

Has there ever been a reverse rug pull in the PNW region?

Meaning models were looking grim/boring but at the last minute everything changed and we wound up with the goods?

We get the rug pulled on cold/snowy weather CONSTANTLY so I would imagine it has happened in reverse but I haven't lived here long enough to have experienced one. 

February 2017 comes to mind for northern areas. Popped up at about 3-4 days out. Models were consistent in showing the energy from Alaska digging out over the ocean but they pretty much all flipped to sending the energy down the coast at the same time.  

[Deweydog]

5 minutes ago, rsktkr said:

Has there ever been a reverse rug pull in the PNW region?

Meaning models were looking grim/boring but at the last minute everything changed and we wound up with the goods?

We get the rug pulled on cold/snowy weather CONSTANTLY so I would imagine it has happened in reverse but I haven't lived here long enough to have experienced one. 

It’s a matter of perspective.  From a forum perspective, a “reverse” rug pull is extremely rare because emphasis will always be on any sign of potential as opposed to the mundane.

But yes, weather is inherently unpredictable, especially on the micro level.

[Jesse]

12z ensembles trended a little warmer in the long range. Looking pretty wet at least.

[Deweydog]

Biggest reverse rug pull I remember was late January 1996. 

[Jesse]

Cloudy and 48 currently after a low of 43. Picked up close to .40" rain overnight.