December 2016 Observations and Model Discussion for the Pacific Northwest

[SilverFallsAndrew]

Mark Nelsen nailed this. Nice little event, but switch over beginning in the south metro. This pic was just taken in Milwaukie. SE Portland. 

 

[SilverFallsAndrew]

We'll see if it is sleet yet, or heavy snow. 

That kind of echo is generally a sleet signature.

[Tyler Mode]

Heavy snow now.  No sleet.  Temp down from 33 to 30 in the last 5 minutes.

[Perturbed Member]

Wow, PDX reporting heavy snow, gusts to 43 mph and visibility down to .25 miles. 

[Goducks09]

Mark Nelsen nailed this. Nice little event, but switch over beginning in the south metro.

 

 

Looks like downtown Milwaukie.  Dang it!  I thought the switch-over wasn't supposed to be until about 4PM, even for places like Milwaukie.

[Tyler Mode]

Battle Ground right now.  Probably the heaviest snow/wind combo I've seen here.  Usually we have one or the other not both.

 

30 even now. 

[SilverFallsAndrew]

I am just glad I was able to snap my 1 day dry streak.

[SilverFallsAndrew]

IMO this is going to end up being very similar to 12/19/05. 

[PV=nRT]

Picture on Twitter from NE Portland:

I was up to 35F before the precip and have since cooled to 30.8F, snowing with some sleet mixed in..

 

(10miles South of Downtown Portland between Gladstone and Milwaukie)

[Timmy]

IMO this is going to end up being very similar to 12/19/05.

 

What happened then?

[SilverFallsAndrew]

What happened then?

 

Essentially it was similar to last Januaries event except a bit more snow and more widespread. Salem got similar amounts with that as they did today, whereas last Jan SLE only got ZR. 

[Deweydog]

IMO this is going to end up being very similar to 12/19/05.

18.

[Front Ranger]

18z NAM moved precip time up considerably, with the main stuff still coming in around 8-9PM.

 

This is 2PM, can't hurt to get an early start!

 

 

The parallel hi-res NAM shows main snow holding off for Seattle until around 9:30-10 pm, then going until 4-5 am. Heavy snow from 1 am - 3 am. Just light precip mainly after that, and too warm for snow after 6-7 am.

[FroYoBro]

Was just sleeting for 10 minutes. Heavy band is getting here and is turning some of the sleet to snow. Probably the last snowflakes of the day for me coming up. The changeover is close here. 

[SilverFallsAndrew]

18.

 

My memory fails me

[Deweydog]

About an inch at the coast near Ilwaco.

 

Thanks, mom.

[SilverFallsAndrew]

Nam drops the 528 thickness line south of me by 5am Sunday morning...

[Front Ranger]

I don't know if I can buy that - precip looks to be ahead of schedule when looking at the radar. Unless what's headed our way just breaks apart, which could happen.

 

That would be unfortunate timing if it ends up right.

 

It shows a couple light snow showers before then, but main bands hold off until at least 9 pm.

[Tyler Mode]

Great temp drop with the onset of the snow.

 

29 currently.  East wind gusting to 17 mph.  DP is up to 26.

[HighlandExperience]

KOMO reporting snow on I-5 near Vader.

 

That means it will be snowing lightly in Centralia pretty soon. I agree with you that the NAM seems off. At this point it doesn't matter anymore 

[FroYoBro]

How much do you have?

Not much. I would guess about a half inch to a 3/4 of an inch. Snowing pretty good right now though. 

[PV=nRT]

Well, I don't have access to everything that I'd like to look at.

With that said, tonight will be tricky with the strong offshore flow. I've seen it go both ways. In one case in 2014 I believe, models showed drying and no precip. We got 2-3 inches from that in Seattle. In other cases, the dry air won.  I'll see later.  I'm a little concerned that outflow from the Fraser will keep the area NE of Bellingham in the cold for the foreseeable future.  I'm not sure about the change to a mix or rain up there Except maybe near the water and south of the hills.

 

Concerning the longer term...Monday is looking potentially interesting - but the moisture leaves before the cold air comes down. Time will tell. But it is looking cold. With the very cold air over western Canada and Alaska and the high latitude block along 150W, combined with some undercutting of the flow along 40N -W Wa will be in the middle of the battle zone. I really don't know the details on how the models are handling tropical moisture and convection at this time (model changes are happening at a fast pace), but very cold air nearby and moisture from the south could make things quite interesting over the next couple of weeks. The end of next week looks interesting. 

 

Models in this pattern tend to be quite unstable. Model riding is dangerous.  It will be difficult to get things right even in the short term.

Well said.  Sometimes there is too much information overload and it is easy to get caught up in the minuta.  Very unstable pattern and the models will oscillate back and forth with time.  The pattern does look interesting the next couple of weeks....something we haven't seen  for the a few years so lets enjoy it. Thanks.

[Deweydog]

Well that band was certainly fun.  Heavy snow with strong winds is just not something we saw too often north of the river.  

[MR.SNOWMIZER]

I am thinking band will reach tacoma in 4 hrs max. Looking at radar it looks like its going to hit hard and fast

[BLI snowman]

Probably a solid 1/2" here now, next band should double or triple that.

[Deweydog]

Probably a solid 1/2" here now, next band should double or triple that.

 

Same here.  Next band should put me right at the mark!

[bainbridgekid]

I am thinking band will reach tacoma in 4 hrs max. Looking at radar it looks like its going to hit hard and fast

Radar certainly makes it look like it.

 

It's 36/11 now at SEA though, so it will probably take a while for things to work their way to the surface. Certainly primed for evaporative cooling though!

[TT-SEA]

26/10 here right now and partly cloudy with a moderate east wind.  

 

Probably good enough for snow?  

[bainbridgekid]

Snow is reaching the ground just South of Chehalis now.

 

http://images.wsdot.wa.gov/Vancouver/005vc06842.jpg

[Randyc321]

Radar certainly makes it look like it.

 

It's 36/11 now at SEA though, so it will probably take a while for things to work their way to the surface. Certainly primed for evaporative cooling though!

 

36/24 at Manitou Beach station on BI  64% humidity.

 

Snow flying on the Centralia cams

[Goducks09]

Good shower in Downtown...coating everything pretty good.

[MossMan]

26/10 here right now and partly cloudy with a moderate east wind.  

 

Probably good enough for snow?  

29F here at work...no idea on DP. I'm hoping the fun will last into the daylight hours tomorrow up here!

[SilverFallsAndrew]

I hope you guys in Seattle get a good 1-3"!

 

This event definitely qualifies as a warning shot IMO!

[TT-SEA]

29F here at work...no idea on DP. I'm hoping the fun will last into the daylight hours tomorrow up here!

 

 

I think everyone north and east of downtown Seattle might stay cold until very early Saturday morning.   

[HighlandExperience]

Reports of light snow up to Chehalis now. I'd imagine it will be snowing in Olympia by 3pm or so. 

[MossMan]

I think everyone north and east of downtown Seattle might stay cold until very early Saturday morning.   

I would be absolutely thrilled with that outcome!!

[TT-SEA]

Reports of light snow up to Chehalis now. I'd imagine it will be snowing in Olympia by 3pm or so. 

 

 

The HRRR keeps insisting the initial band will impale itself on dry offshore flow and the band coming into Portland now is the real deal for Seattle.   

 

I am not sure what to think.  

[DareDuck]

4"' of new snow since 5am or so. 6"' on the ground. Temp is 18 and winds have been calm generally. Was hovering around 16 most of the morning until recently. Hoping we can stay colder than projected. Already have more snow than projected.

[Goducks09]

Still some strong echos SW of PDX yet to roll in...hopefully all snow.

[FroYoBro]

Still some strong echos SW of PDX yet to roll in...hopefully all snow.

I'll let you know in a few minutes.