December 2016 Observations and Model Discussion for the Pacific Northwest

[snow_wizard]

I trust you here. Been on this forum for years your one of the vets here that would know this.

 

Do you think midnight is still accurate when it turns to snow or ealier.

 

I don't think there will be any rain by dark tomorrow evening.

[MR.SNOWMIZER]

This looks way colder than mid 30's next week.

[TT-SEA]

I don't think there will be any rain by dark tomorrow evening.

 

I think there will be rain up here even until 7 or 8 p.m. based on the WRF.  

[Abbotsford_wx]

Environment Canada is also being very conservative up here...

 

 

Sorry I forgot how to convert it to degrees F... but 1C is about 34F

 

[snow_wizard]

Environment Canada is also being very conservative up here...

 

ECdec302016.JPG

 

Sorry I forgot how to convert it to degrees F... but 1C is about 34F

Totally insane. Shave at least 10F off of that.

[snow_wizard]

Another thing that gives me hope for tomorrow night is the low will be in an intensifying stage when it comes through. Some kind of convergence is almost certain given the squashed zone of lowest pressure drops right over us.

[bainbridgekid]

I don't think there will be any rain by dark tomorrow evening.

IDK.

 

It almost always takes several hours longer than modeled for the lowest levels to cool to freezing when colder air is moving in from the North like this.

 

I would expect precip to be snow in Bellingham by sunset and around Seattle by 8-10 PM. I doubt SEA freezes till after midnight.

 

8 PM tomorrow to 6 AM Sunday definitely looks pretty interesting though. I have hope for a relatively widespread 1-2" with isolated areas getting more. Doesn't look good for anywhere SW of Seattle though IMO.

[BLI snowman]

Environment Canada is also being very conservative up here...

 

ECdec302016.JPG

 

Sorry I forgot how to convert it to degrees F... but 1C is about 34F

 

Yikes, that will bust hard.

[snow_wizard]

I think there will be rain up here even until 7 or 8 p.m. based on the WRF.

Possible. I'm less confident about the exact changeover time than I am about the fact most of King County will have some snow. I do know the cold often moves in quicker than expected with events that actually work out.

[The Swamp]

IDK.

 

It almost always takes several hours longer than modeled for the lowest levels to cool to freezing when colder air is moving in from the North like this.

 

I would expect precip to be snow in Bellingham by sunset and around Seattle by 8-10 PM. I doubt SEA freezes till after midnight.

 

8 PM tomorrow to 6 AM Sunday definitely looks pretty interesting though. I have hope for a relatively widespread 1-2" with isolated areas getting more. Doesn't look good for anywhere SW of Seattle though IMO.

 

Thanks for verifying my thoughts.

 

I do think the swamp will see some snow amounting to 0"-Trace that will look like a heavy frost.

 

We can then hold onto this snowpack/heavy frost look for a week while we wait for our next opportunity just ten days away.

[snow_wizard]

IDK.

 

It almost always takes several hours longer than modeled for the lowest levels to cool to freezing when colder air is moving in from the North like this.

 

I would expect precip to be snow in Bellingham by sunset and around Seattle by 8-10 PM. I doubt SEA freezes till after midnight.

 

8 PM tomorrow to 6 AM Sunday definitely looks pretty interesting though. I have hope for a relatively widespread 1-2" with isolated areas getting more. Doesn't look good for anywhere SW of Seattle though IMO.

Going to be interesting for sure. A slightly more sluggish invasion of cold air could mean the moisture will hang around longer also. I have seen plenty of these where the cold arrives ahead of schedule though. Also bear in mind the air mass is already pretty cold.

[TT-SEA]

Possible. I'm less confident about the exact changeover time than I am about the fact most of King County will have some snow. I do know the cold often moves in quicker than expected with events that actually work out.

I am pretty sure most areas below 750 feet will have mostly bare ground by Sunday evening after a high in the mid to upper 30s.

 

The only mitigating factor will be drier air moving in on Sunday.

[Jbolin]

I am pretty sure most areas below 750 feet will have mostly bare ground by Sunday evening after a high in the mid to upper 30s.

 

The only mitigating factor will be drier air moving in on Sunday.

It's so infuriating knowing how pessimistic you can be yet sickly comforting knowing you are also right most of the time.

[TT-SEA]

IDK.

 

It almost always takes several hours longer than modeled for the lowest levels to cool to freezing when colder air is moving in from the North like this.

 

I would expect precip to be snow in Bellingham by sunset and around Seattle by 8-10 PM. I doubt SEA freezes till after midnight.

 

8 PM tomorrow to 6 AM Sunday definitely looks pretty interesting though. I have hope for a relatively widespread 1-2" with isolated areas getting more. Doesn't look good for anywhere SW of Seattle though IMO.

Regarding SEA... GFS MOS does not show SEA going below freezing until Sunday evening for the first time. ECMWF agrees.

[TT-SEA]

It's so infuriating knowing how pessimistic you can be yet sickly comforting knowing you are also right most of the time.

Blame nature... I hate the time between the moisture moving out and truly cold air arriving.

[bainbridgekid]

Regarding SEA... GFS MOS does not show SEA going below freezing until Sunday evening for the first time. ECMWF agrees.

It will be close whether they sneak down to freezing Saturday night/Sunday morning.

 

In a moist airmass, they usually cool painfully slowly in these types of setups.

[MR.SNOWMIZER]

Regarding SEA... GFS MOS does not show SEA going below freezing until Sunday evening for the first time. ECMWF agrees.

Seattle proper is way warmer than most other places.

[kokaneekidz]

Totally insane. Shave at least 10F off of that.

They will lower the temps once the actual airmass makes it into our region/ Just making sure it doesn't hook a left turn accidently.... Next weekend is starting to look phenomonal as well

[TT-SEA]

Seattle proper is way warmer than most other places.

ECMWF shows widespread 37-39 degree temps on Sunday afternoon from Seattle to Eugene.

[MossMan]

Just hit freezing!

[bainbridgekid]

ECMWF shows widespread 37-39 degree temps on Sunday afternoon from Seattle to Eugene.

I don't normally pay much attention to its DP forecast, but the WRF shows highs around 36 Sunday with DP's around 20.

 

Wouldn't be much melting if that were correct, but I have a feeling the cold, drier air will take a bit longer than that to establish itself.

[SilverFallsAndrew]

So just running the stats. Here are the coldest January lows at PDX since 1980...

 

13 - 1980

14 - 1982

17 - 1996

18 - 2004

19 - 2007&1984

 

Really good chance PDX has their coldest January low since 1982. A low of 12 a Mark Nelsen has forecast would be the coldest January low since 1974.

[Jbolin]

Looks like the last time measurable snow in Seattle on New Years Eve 1968 with 9.3"

[Abbotsford_wx]

They will lower the temps once the actual airmass makes it into our region/ Just making sure it doesn't hook a left turn accidently.... Next weekend is starting to look phenomonal as well

 

Probably, since there is not much cold air upstream yet. The trough is going to be pretty fast moving, so things will progress quickly (assuming things go as planned).

[ShawniganLake]

ECMWF shows widespread 37-39 degree temps on Sunday afternoon from Seattle to Eugene.

It only got up to 39 here today with clear blue skies. Already down to 29. The trajectory of the low will likely leave me mostly dry tomorrow, unfortunately.

[TT-SEA]

I don't normally pay much attention to its DP forecast, but the WRF shows highs around 36 Sunday with DP's around 20.

 

Wouldn't be much melting if that were correct, but I have a feeling the cold, drier air will take a bit longer than that to establish itself.

 

 

WRF is probably a little too cool as usual... maybe 37 or 38 with a dewpoint falling into the 20s with some sun.    Guessing it will be a 'snow in shady places' situation depending on how much actually falls.    

[snow_wizard]

Seattle proper is way warmer than most other places.

I also think everyone is really underestimating how swiftly the cold air is going to blast in. I expect no melting Sunday at all except maybe in the sun. This is a true Arctic front moving through after all. I have high confidence on this.

[bainbridgekid]

WRF is probably a little too cool as usual... maybe 37 or 38 with a dewpoint falling into the 20s with some sun.    Guessing it will be a 'snow in shady places' situation depending on how much actually falls.    

Looking closer, the WRF actually shows DP's in the mid teens Sunday afternoon. That would be impressive and make for very little melting.

 

Anybody who gets more than an inch should still have snow on the ground Monday morning I think. Big question mark if many areas can get more than that though.

[Phil]

Any thoughts on this?

Helps w/ blocking in the long run.

[HighlandExperience]

I also think everyone is really underestimating how swiftly the cold air is going to blast in. I expect no melting Sunday at all except maybe in the sun. This is a true Arctic front moving through after all. I have high confidence on this.

Hope so. All of the recent fronts have been pathetic

[Timmy]

I just noticed the hi res wrf didn't run for 12z. Is anyone able to see it?

[snow_wizard]

Hope so. All of the recent fronts have been pathetic

This is way different. The previous ones were all warning shots although it did get down to 18 here one night. It's almost funny to see how everyone is underestimating this. The little cold shot we had in late Nov 2014 was cold enough to keep any snow from melting after it fell in the morning and this thing is much more impressive.

[MossMan]

The last round of snow came many hours ahead of schedule and wasn't supposed to amount to anything until that Friday evening....rain turned to snow not long after sunrise and went on throughout much of the day. Many on here were convinced no places below 500ft would see anything...got an inch at sea level and just over 2" at my 350ft elevation. You just never know sometimes.

[MossMan]

This is way different. The previous ones were all warning shots although it did get down to 18 here one night. It's almost funny to see how everyone is underestimating this. The little cold shot we had in late Nov 2014 was cold enough to keep any snow from melting after it fell in the morning and this thing is much more impressive.

None of my snow went away for a week after that one! This was taken a few days after the snow.

[luminen]

Just got back from the heart of the Canadian Rockies in the heart of winter; more specifically, Field, BC and Lake Louise, AB. I needed to be in a subarctic/Dfc climate and boy did it deliver. It wasn't a blizzard or anything but it was nice to get out of this mucky moss infested and dreary climate. The weather while I was there was 15F-20F and snowing or cloudy. If this upcoming cold wave had come just a little earlier it would've been perfect though.

 

That last pic is me randomly eating a big long thing of snow. 

[SilverFallsAndrew]

Latest CFS has a warm February and then a cold March. 

[van city]

Helps w/ blocking in the long run.

Thanks Phil.

[Heavy Snow]

I'm cautiously optimistic right now. I'm hoping for a good set of 00z model runs tonight. I can't think of a better way to end the year than an incredible set of 00z model runs tomorrow night as we watch snow and fireworks light up the sky tomorrow at midnight. Let's ring in the New Year with snow!

[SilverFallsAndrew]

Just got back from the heart of the Canadian Rockies in the heart of winter; more specifically, Field, BC and Lake Louise, AB. I needed to be in a subarctic/Dfc climate and boy did it deliver. It wasn't a blizzard or anything but it was nice to get out of this mucky moss infested and dreary climate. The weather while I was there was 15F-20F and snowing or cloudy. If this upcoming cold wave had come just a little earlier it would've been perfect though.

 

That last pic is me randomly eating a big long thing of snow. 

 

Amazing pics!

[TT-SEA]

MM5 NAM shows most of the precip when its still a little too warm for true lowland snow tomorrow evening.