December 2016 Observations and Model Discussion for the Pacific Northwest

[seattleweatherguy]

Your area will get the benefit of the moisture running through the gauntlet of cold outflow from the passes. When that happens it can cause enhancement.

So like a conversation zone of some sort?

[Kayla]

After the 12z's this morning I went into retreat. Then Mark did too, and I honestly follow him like The Grateful Dead. Hard to get off that thinking at this point. The NWS stuff sounds swell, they've really fell in love with that f-word lately, but it does sound like rationalizing a bit of an unrealistic call.

 

You sure did, but I don't blame you! I actually worked for Mark for a while and did my best to become a sponge of his knowledge. One smart guy. 

[snow_wizard]

I'm very intrigued it's getting colder in spite of the strong wind here. That means the cold has some good depth to it.

[MikeInEverett]

So like a conversation zone of some sort?

Yeah, the enhanced moisture will lead to more snowfall, and hence, will lead to a lot of conversations about the weather happening there. A conversation zone.

[Front Ranger]

I think I like where the Euro's going at day 3.

 

Hmm, at day 4 it's not about to get as cold as the GFS, but it does look like it's about to get snowy.

[Perturbed Member]

Sure, but I'm talking face value snow totals on the models. 2-4" isn't an outlandish call at this point for the Portland area.

 

NAM went for 2-3 inches, GFS 1-3 inches, Euro 3-5 inches, and GEM 4-6 inches. 2-4 is what I'm thinking as well. The models are on board with that and the NWS seems confident in it as well. So what is the reason now for thinking we get less than that? The airmass looks like it is good enough too. Earlier I was mostly concerned that the trend for weaker and further south/offshore would continue until we got very little precip or it came at the worst possible time of day, but it seems like the models have somewhat come together a bit on a decent solution. 

[snow_wizard]

So like a conversation zone of some sort?

The relatively warm / moist air comes in contact with the outflow winds and condenses.

[Phil]

Hmm, at day 4 it's not about to get as cold as the GFS, but it does look like it's about to get snowy.

It's not going to be as good.

[Goducks09]

I think I like where the Euro's going at day 3..

 

 

...day 4 too...

[Kayla]

Precip-wise, yes. How much ends up as snow, and how much ends up as mixed precip/ice is another matter.

 

Precip is looking like more than 0.2 - 0.4". Closer to 0.4 - 0.6" around PDX seems like a safe precip forecast at this point.

[Front Ranger]

It's not going to be as good.

 

Helluva lot better than 12z Euro.

[Front Ranger]

Precip is looking like more than 0.2 - 0.4". Closer to 0.4 - 0.6" around PDX seems like a safe precip forecast at this point.

 

Sure, and if most of that fell as snow, awesome! Just wouldn't surprise me if the majority of it fell as freezing rain for PDX. Hopefully not.

[Phil]

Helluva lot better than 12z Euro.

It'll be a pedestrian run overall. Next.

[Front Ranger]

It'll be a pedestrian run overall. Next.

 

It took steps in the right direction for the mid range, just like GFS.

[MossMan]

It'll be a pedestrian run overall. Next.

Thanks Phil!!!!!!!

I'm going to bed.

[Phil]

It took steps in the right direction for the mid range, just like GFS.

The Arctic front is actually farther north in BC at 108hrs. How is that better?

[SilverFallsAndrew]

A line of clearing is actually working up the valley. EUG down to 28 on the hour, dp has dropped to 23 there. Down to 23 here under starry skies. 

[Front Ranger]

Uber-pedestrian pattern at day 5. Phil's monster +NAO/Hudson Bay vortex of terror even went away.

 

[Front Ranger]

The Arctic front is actually farther north in BC at 108hrs. How is that better?

 

Compare to 12z. The overall pattern, the big picture is much better.

[Phil]

Uber-pedestrian pattern at day 5. Phil's monster +NAO of terror even went away.

 

pedestrian.gif

That's true, but the waveguide out of the NEPAC flattened for some reason, hence the front makes less progress. Probably a fluke but verbatim it's pedestrian.

[epiceast]

Not outlandish, but probably a bit bullish. Somewhere far NW metro will probably see around 4", while downtown and SE areas may struggle to see 1".

 

But hoping for 2-4"++!

Far NW metro of Portland is a forest or a farm. I'm guessing Forest Grove/Hillsboro get the most by far because of cold air damming. What's really weird is that foothills SE of PDX never seem to do much better than downtown until you get to Sandy/1k' level unlike Seattle foothills where even 200' make a difference.

[MossMan]

Down to 19F!

[Phil]

Thanks Phil!!!!!!!

I'm going to bed.

Lol, sorry man.

[Deweydog]

Wind is pretty incredible out here tonight. Probably the strongest east winds since we moved out here in 2010.

[MossMan]

Wind is pretty incredible out here tonight. Probably the strongest east winds since we moved out here in 2010.

Still have power?

[Phil]

This run might actually end up being worse than 12z.

[MR.SNOWMIZER]

How fast Dewey

[Front Ranger]

One thing is for sure. There's going to be a very frigid blob of air floating around North America next week.

[luterra]

A line of clearing is actually working up the valley. EUG down to 28 on the hour, dp has dropped to 23 there. Down to 23 here under starry skies. 

 

Dropped from 33 to 27.5 here when the skies cleared with no wind, now bouncing back up again as a light breeze returns.  Dew point 25 and falling, sky still mostly clear.

[HighlandExperience]

I'm actually pretty happy with the Euro snowfall maps for a few reasons:

 

1. It shows a good chunk of the snow holding off until Friday morning/early afternoon. Get to actually see it.

 

2. Shows fair amounts over most of Puget Sound area, with anywhere from 2-5 inches (we won't talk about the Swamp).

 

3. Has more, in general, than the 12z.

You think it will stay snow Friday morning?

[Deweydog]

Still have power?

Oh yeah. We've only lost it twice out here in 6.5 years.

[MossMan]

You think it will stay snow Friday morning?

So a Friday event now?

[Heavy Snow]

This run might actually end up being worse than 12z.

 

Yeah you're right. The modified Arctic air doesn't even make it into Eastern WA/OR like in previous runs.

[Deweydog]

How fast Dewey

45-50 in gusts probably. We're in a pretty sheltered spot typically. This one just has our number.

[epiceast]

WRF semi clown range(hr 180) gives a big snowstorm to Hood Canal and Columbia basin.

[MossMan]

One thing is for sure. There's going to be a very frigid blob of air floating around North America next week.

Right over Puget sound! Models will settle on that solution by Saturday 00z's

[Deweydog]

One thing is for sure. There's going to be a very frigid blob of air floating around North America next week.

Just need that block to tilt positively, otherwise it's gonna be tough to take off a path of least resistance.

[Jesse]

Worst Euro run in years tonight!

[Phil]

Yeah you're right. The modified Arctic air doesn't even make it into Eastern WA/OR like in previous runs.

Need to amplify that waveguide to dig the trough. Otherwise it's a flatter wavetrain, more progressive US trough, and a quicker/easier return to a +EPO/+AO as 120E forcing takes over. Bad run.

[MossMan]

45-50 in gusts probably. We're in a pretty sheltered spot typically. This one just has our number.

Good thing you put that patio furniture away last week!