December Weather In the PNW

[TT-SEA]

06Z GFS and almost all of the ensemble members are totally dry for Christmas Eve.

 

00Z ECMWF showed a snowstorm for most of the region from Portland northward to BC that day.

 

The morning runs will be interesting!  

[Phil]

D8-13 00z EPS. This just screams off-equator Pacific forcing. Lots of poleward heat/mass dumpage.

 

Meanwhile, the NATL cells are narrowed/intensified.

 

[catnip]

06Z GFS and almost all of the ensemble members are totally dry for Christmas Eve.

 

00Z ECMWF showed a snowstorm for most of the region from Portland northward to BC that day.

 

The morning runs will be interesting!  

 

Don't forget the GEM.

[Brian_in_Leavenworth]

D8-13 00z EPS. This just screams off-equator Pacific forcing. Lots of poleward heat/mass dumpage.

Meanwhile, the NATL cells are narrowed/intensified.

Is that good for us?

[Phil]

Lol..the WHEM meridional mode is out of control. This biases deep convection towards the NH, which increases poleward heat fluxes on the NH half of the globe. The opposite is true in the SH.

 

[crf450ish]

It’s about to get COLD at my house and surrounding areas

 

http://forecast.weather.gov/MapClick.php?lon=-118.31172878194167&lat=47.98625596846651#.Wjp2vGKIaEd

[Phil]

Is that good for us?

It could be good or bad during boreal winter, depending on other peripheral boundary conditions.

 

It does favor Pacific-based blocking over NATL-based blocking, which often leads to increased frequency and intensity of -EPOs/Arctic airmasses into North America.

 

However, the lack of downstream blocking/wavebreaking (+NAO et al) can bias longwave troughing into the eastern US and destructively interfere w/ SE-ridging when the wavebumber is decreased.

[crf450ish]

Wasn’t something good supposed to happen 10 days ago?

[Brian_in_Leavenworth]

It could be good or bad during boreal winter, depending on other peripheral boundary conditions.

It does favor Pacific-based blocking over NATL-based blocking, which often leads to increased frequency and intensity of -EPOs/Arctic airmasses into North America.

However, the lack of downstream blocking/wavebreaking (+NAO et al) can bias longwave troughing into the eastern US and destructively interfere w/ SE-ridging when the wavebumber is decreased.

So the ridge could park over us instead Alaska? Sounds like the odds are better for us though without the NATL blocking

[Phil]

Lol..the WHEM meridional mode is out of control. This biases deep convection towards the NH, which increases poleward heat fluxes on the NH half of the globe. The opposite is true in the SH.

 

Add in the enhanced NH component of the west-Pacific warm pool, and you have a super heat flux machine across the NH.

[Deweydog]

I keep a heat flux machine in the spare bedroom.

[Phil]

So the ridge could park over us instead Alaska? Sounds like the odds are better for us though without the NATL blocking

Well if it’s not parked over AK it’s not a -EPO. Where exactly it sets up, from year to year, can vary substantially. from year to year.

 

As for your odds w/o NATL blocking..I think that (in the long run) it actually hurts a bit, because it elongates the wavetrain/decreases the WHEM wavenumber.

[TT-SEA]

Even some clearing up at Snoqualmie Summit this morning... after about 2 feet of new snow since Monday.

 

Base at the bottom is now 46 inches... with 99 inches at the top.    Should be great skiing for all of Christmas break now. 

 

[MossMan]

Wait..I thought “WHAM” was a joke.

 

WHEM = Western Hemisphere.

It was. I was just trying to be funny...I failed. Matt is very disappointed in me.

[MossMan]

Down to 31! 35 degrees even at 4am with lingering rain...then the precip clears out and instantly down to freezing.

[TT-SEA]

Down to 31! 35 degrees even at 4am with lingering rain...then the precip clears out and instantly down to freezing.

 

I saw a couple snowflakes this morning!    Otherwise it just looks like a typical wet winter morning out there.    

[BLI snowman]

Should be pretty foggy and gunked in tomorrow. 12z NAM shows a daytime high of 30 for VUO.

[TT-SEA]

Should be pretty foggy and gunked in tomorrow. 12z NAM shows a daytime high of 30 for VUO.

 

ECMWF shows around 40 there with morning fog and afternoon high clouds.  

[MR.SNOWMIZER]

Where is this euro snow storm map

[MossMan]

Brisk Northish wind out there!

[BLI snowman]

ECMWF shows around 40 there with morning fog and afternoon high clouds.  

 

Probably will be somewhere in the middle. Gradients look totally dead, pretty difficult to avoid staying socked in.

[BLI snowman]

Definitely trending wetter for Friday. Could be lots of 36 degree rain around Portland.

[TT-SEA]

Daylight has revealed a tiny coating of snow in the backyard this morning.    The other side of the house has nothing though.   So we were right on the line!  

 

[MR.SNOWMIZER]

Daylight has revealed a tiny coating of snow in the backyard this morning.    The other side of the house has nothing though.   So we were right on the line!  

 

Do think the snow line was that extreme? that's amazing. I have seen snow on tops of tree's and nothing at the base up in the mountains.

[TT-SEA]

Do think the snow line was that extreme? that's amazing. I have seen snow on tops of tree's and nothing at the base up in the mountains.

 

I have seen the same thing with the trees on the ridge... with some trees having snow just on the top.   

 

I think in this case... that part of the yard is lower and might have been a degree cooler last night.  

[Jbolin]

I have seen the same thing with the trees on the ridge... with some trees having snow just on the top.   

 

I think in this case... that part of the yard is lower and might have been a degree cooler last night.  

Ok so Tim's house sits smack dab in the middle of two super hypersensitive micro-climates.

 

Joking aside, I have seen nearly the same thing in Buffalo, NY four years ago where one side of a house had 6 inches and the other side had an inch, talk about extreme

[MR.SNOWMIZER]

12z not dry on xmas eve.

[TT-SEA]

Ok so Tim's house sits smack dab in the middle of two super hypersensitive micro-climates.

 

Joking aside, I have seen nearly the same thing in Buffalo, NY four years ago where one side of a house had 6 inches and the other side had an inch, talk about extreme

 

For the record... I don't think it was raining on one side of the house and snowing on the other side.   I think there was some 34-degree snow in the air last night and the lowest part of the yard was slightly cooler and there is a tiny accumulation there but not in other spots.  

[TT-SEA]

12z not dry on xmas eve.

 

Not even close.   

 

What a complete crash.   Faster and faster and faster on each run.   The models just cannot catch up.   The GFS has been trending hundreds of miles east on every single run.   

 

At this rate... the Christmas Eve system will actually be here tomorrow.  

[Phil]

Umm..yeah. Check out the average 500mb pattern over the last four winters (2013/14-15-16-17).

 

Look familiar? #WPACForcing #WarmPool

 

[MR.SNOWMIZER]

Tuesday could end up interesting.

[MossMan]

Sounds like places like Darrington got a few inches which was confirmed by cars coming west on HWY 530 with snow on them this morning when I was getting on I-5.

[MossMan]

Not even close.

 

What a complete crash. Faster and faster and faster on each run. The models just cannot catch up. The GFS has been trending hundreds of miles east on every single run.

 

At this rate... the Christmas Eve system will actually be here tomorrow.

Matt is not going to be happy.

[GobBluth]

the inconsistency of the gfs is either a part of its brilliance or an indication it should be always ignored.

[ShawniganLake]

Where is this euro snow storm map

[High Desert Mat!]

 

Where is this euro snow storm map

How about oregons now?

[Lisa0527]

the inconsistency of the gfs is either a part of its brilliance or an indication it should be always ignored.

I can’t even begin to understand the differences between the 06Z and the 12Z GFS. How is it possible for models to flip so dramatically run to run? The GEM at least seems to have consistency going for it.

[HighlandExperience]

12z GFS does show some lowland snow with the Friday system. Just a hair too warm for the Christmas Eve/Christmas system.

 

Hope to keep the Euro in our camp today for that one.

 

Hope the euro holds its ground. Getting 2-5 inches of snow on Christmas eve would be something!

[Timmy]

The gfs is sure a stinker. Weird run

[ShawniganLake]

How about oregons now?