December 2015 in the Pacific Northwest

[Gradient Keeper]

Seems like it could be a situation where the outflow prone areas actually mix out and are slightly too warm, but the cold air damming spots wet bulb to snow.

Typically, yeah favors east slopes of the Coast Range, Forest Grove, places like that. The cold pool is a huge player in this though.

[SilverFallsAndrew]

Typically, yeah favors east slopes of the Coast Range, Forest Grove, places like that. The cold pool is a huge player in this though.

 

How so?

[Timmy]

How so?

It's at least the reason the lower 1000' has a chance.

[SilverFallsAndrew]

It's at least the reason the lower 1000' has a chance.

 

The Columbia Basin "cold pool?"

[snow_wizard]

El Paso is over 3,700 ft. They get under 10 inches of precip a year with about 7 inches of it being snow, which is more than most lowland locations on the I-5 corridor in the PNW. Amarillo averages about 18 inches of snow per year.

 

The very low numbers for the I-5 corridor are extremely misleading.   These days the NWS uses 30 year averages.  The normals prior to around 1980 were MUCH higher.  It remains to be seen if we can back to what the good old days averaged or at least close to that.  For an example SEA averaged about 16 inches per winter from 1945 through 1975.

[snow_wizard]

Seems like it could be a situation where the outflow prone areas actually mix out and are slightly too warm, but the cold air damming spots wet bulb to snow.

 

Exactly what the models have been showing.  I'm hoping the outflow will be a little weaker than progged so that won''t happen.

[SilverFallsAndrew]

Special weather statement issued for Northern Oregon Cascade foothills. 

 

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE PORTLAND OR
249 PM PST SAT DEC 26 2015

ORZ010-WAZ040-271500-
NORTHERN OREGON CASCADE FOOTHILLS-
SOUTH WASHINGTON CASCADE FOOTHILLS-
INCLUDING THE CITIES OF...SANDY...ESTACADA...
SILVER FALLS STATE PARK...SWEET HOME...TOUTLE...ARIEL...
LAKE MERWIN...YALE LAKE...COUGAR
249 PM PST SAT DEC 26 2015

...LOW SNOW LEVELS LATE TONIGHT THROUGH SUNDAY...

THE NEXT FRONTAL SYSTEM WILL SPREAD PRECIPITATION TO THE NORTH
OREGON AND SOUTH WASHINGTON CASCADE FOOTHILLS BEGINNING LATE
TONIGHT AND CONTINUING THROUGH SUNDAY. SNOW LEVELS ARE EXPECTED TO
BE 500 TO 1000 FEET LATE TONIGHT THROUGH SUNDAY...LOWEST IN AREAS
CLOSEST TO THE COLUMBIA GORGE. ACCUMULATIONS UP TO 3 INCHES ARE
LIKELY BY LATE SUNDAY AFTERNOON...WITH THE HIGHEST AMOUNTS ABOVE
1000 FEET.

[The Swamp]

As for the longer term, it appears the MJO should enter favorable territory for us again by mid Jan or so. Every time the MJO has gotten into the 2 through 5 range over the past few months the PNA has tanked pretty good. With a good AO drop forecast in the near future a -PNA in combination with that could potentially treat us pretty well. Past history tells us that when the PNA is negative we only need either the AO, NAO, or EPO to be minus to be assured of a good shot at getting an Arctic outbreak. 2007-08 and this past week show us very clearly what happens when only the PNA is minus. I had 4 consecutive days with snow mixed with rain or wet snow and only got 0.1" out of all of it. Mid January will be a window of opportunity for us...nothing more nothing less.

 

I'm really tired of Tim trying to make it sound like I have no idea what I'm talking about.

I understand Jim. You know your stuff and are enthusiastic about cold and snow.

 

Tim lives at Snoqualmie pass. He's supposed to get snow.

 

He tells us and shows us that it snowed at his house. It'd be like him telling us a bear shits in the woods. Ya think?!?!

[Deweydog]

It's at least the reason the lower 1000' has a chance.

The mere existence of offshore flow and somewhat lower dew points is the only thing even tangentially associated with the basin cold pool. It's essentially a non-factor and as mentioned by Bainbridge flu actually be an inhibitor.

[snow_wizard]

Looks like a very dry period coming up.  Numbers for the entire 384 hour period on the GFS have been running 0.50 to 0.75 for most areas.  It also indicates California will continue to struggle to get much.  Totally amazing how they can't break out of the drought no matter what index combination we have or what the ENSO is.  The big question for the Western lowlands is how perfectly the pattern will work out for low level cold.  This could be a decent cold period we're getting into.  It's already been a couple of weeks since it hit 50 here.

[snow_wizard]

The mere existence of offshore flow and somewhat lower dew points is the only thing even tangentially associated with the basin cold pool. It's essentially a non-factor and as mentioned by Bainbridge flu actually be an inhibitor.

 

flu?

 

I wouldn't say the Basin cold pool is a non factor.  In some cases it can be become quite extreme and exert quite an influence on the outflow areas.

[SilverFallsAndrew]

I think several members of this forum vastly overrate the east winds snow making abilities. 

[SilverFallsAndrew]

I think several members of this forum vastly overrate the east winds snow making abilities. 

 

I say this with love.

[Timmy]

I think several members of this forum vastly overrate the east winds snow making abilities.

 

It is the reason Scappoose and areas north and west of pdx do so much better in these setups. I believe Jan 11? We had a foot of snow overnight when. Pdx had little to none. I just estimate it in these parts, not overestimate

[MossMan]

Got up to a whopping 35 degrees today! Cloudy and cold day.

[Deweydog]

flu?

 

I wouldn't say the Basin cold pool is a non factor. In some cases it can be become quite extreme and exert quite an influence on the outflow areas.

Ducking autocorrect... outflow.

 

The basin is very relevant, just not really tomorrow.

[SilverFallsAndrew]

Only 35 right now in Silverton. On the valley floor. Looks like a chilly near miss for these lowlanders.

[TT-SEA]

4 inches of crusty snow makes for some awesome sledding conditions.   She is flying down our little hill.   

 

[Jesse]

Spent the afternoon touring the Pittock Mansion. It was 34 up there with a moderate east wind when we left a bit ago.

 

PDX down to a 39/29 spread.

 

I will say I'm glad I have a little bit of elevation going into this one.

[TT-SEA]

Tim lives at Snoqualmie pass. He's supposed to get snow.

 

He tells us and shows us that it snowed at his house. It'd be like him telling us a bear shits in the woods. Ya think?!?!

 

Almost no snow here the last couple years... its not a given!  

[SilverFallsAndrew]

38/26 at EUG

38/28 at SLE

 

34/24 at my location

[Snowman5678]

Beautiful day along I-90 from North Bend to Cle Elum. Car thermometer got down to around 20 degrees in the Roslyn, Cle Elum area at about 1:30. Not bad! I'll post some pictures in a little while.

[luvssnow_spokane]

Watch out in 2017-18, assuming it's a La Niña winter. Would be an early-biased +QBO under declining solar and a relatively strong BDC. Would be the first of it's kind since the 1950s.

Dear Lord!

[luvssnow_spokane]

Almost no snow here the last couple years... its not a given!  

But about 200% more likely... Nothing is a given.

[GHweatherChris]

Nice band of moisture offshore tracking NE right now, I am not expecting anything frozen but am really hoping to see flakes this evening, looks like it should move in around 7 or so, fingers crossed.  925 temps are still below 0 so there could be a surprise.

[snow_wizard]

Dear Lord!

 

In all seriousness the remainder of this decade will probably show us whether this climate has any potential left whatsoever.  With a Nina almost certain to ensue and solar a certainty to be very low by this time next year.  We shall see...

[Kayla]

Already back down to 32º here after a high of 35º with very calm winds all day. Seems likely it will be all snow tonight into tomorrow morning in the West Hills with this setup.

[snow_wizard]

Some pretty fair numbers right now.  SEA is 39 / 29 and Lester (at 1600 in the upper Green River Valley) is 29 / 24.

[snow_wizard]

It's pretty remarkable how the cold shot after this little overrunning event has gotten consistently colder and longer on the models since it was first shown several days ago.  On the 18z both the ensemble mean and operational take 850s down to -6 now.  That should get the cold snap off to a good start.

 

On the 18z ensemble a number of members drop below the zero line again later in the run.

[Jesse]

DP down to 27 in Troutdale. That can't be a bad sign.

[Jesse]

It's pretty remarkable how the cold shot after this little overrunning event has gotten consistently colder and longer on the models since it was first shown several days ago.  On the 18z both the ensemble mean and operational take 850s down to -6 now.  That should get the cold snap off to a good start.

 

On the 18z ensemble a number of members drop below the zero line again later in the run.

 

The 18Z ensemble is much cooler overall, with lots of members approaching zero or lower throughout.

 

This could be a longish cool spell reinforced with shots of cold to our east.

[snow_wizard]

Big improvement on the 18z for lowland snow tomorrow.  Considerably higher precip amounts for the East Puget Sound lowlands with some snow being shown there now.

[TT-SEA]

Big improvmenet on the 18z for lowland snow tomorrow.  Considerably higher precip amounts for the East Puget Sound lowlands with some snow being shonw there now.

 

 

Precip intensity is probably key for this event.

[snow_wizard]

The 18Z ensemble is much cooler overall, with lots of members approaching zero or lower throughout.

 

This could be a longish cool spell reinforced with shots of cold to our east.

 

This is looking decently cold.  Even if a lot of the cold is low level and it's dry it beats the typical El Nino fare of dying warm fronts by a mile and a half.

[Brennan]

I am not a fan on Komo4's new website. The weather section is bogus. I want my old graphics back!

[MR.SNOWMIZER]

I am not a fan on Komo4's new website. The weather section is bogus. I want my old graphics back!

Every time i go to there web my computer gets attacked by advertisments and stuff.

[snow_wizard]

Precip intensity is probably key for this event.

 

No question.  I was very happy to see the big improvement on this run.  No doubt the sat pic looks impressive and we have decently cold air to work with.  Down to 35 here now.

[Jesse]

This is looking decently cold.  Even if a lot of the cold is low level and it's dry it beats the typical El Nino fare of dying warm fronts by a mile and a half.

 

Couldn't agree more.

[TT-SEA]

No question.  I was very happy to see the big improvement on this run.  No doubt the sat pic looks impressive and we have decently cold air to work with.  Down to 35 here now.

 

 

Looks like precip does not arrive until mid-morning.   Too bad its not coming in now.

[MR.SNOWMIZER]

Looks like precip does not arrive until mid-morning.   Too bad its not coming in now.

You going by sat and radar? or the models?