December 2016 Observations and Model Discussion for the Pacific Northwest

[Heavy Snow]

6z having some fun

 

http://i.imgur.com/nud9arz.png

 

Yup, you beat me to it. The updated run of the 06z GFS starts to show an Arctic trough starting to dig around day 7. The end result is an Arctic Blast for the PNW around day 9.

 

http://maps1.pivotalweather.com/maps/models/gfs/2016120506/168/500h_anom.na.pnghttp://maps1.pivotalweather.com/maps/models/gfs/2016120506/222/850th_nb.na.png

[Heavy Snow]

Wow, reload incoming at day 12.

 

http://maps1.pivotalweather.com/maps/models/gfs/2016120506/288/500h_anom.na.png

[Gradient Keeper]

I've been doing this for quite a few years and I have never seen back to back runs like this be so close to delivering not just a true regional arctic blast, but possible historic cold. I'm not counting 2008 or events that actually panned out. The potential is off the charts coming up after day 6. Usually after we see one amazing, incredibly cold run with a massive arctic blast/snow we see the very next run either watering it down or completely different. To see this on consecutive runs means something, and I believe something big is coming. And to see this before day 10 only increases my confidence. Of course the odds are against it I'm sure, but when are they not. This seems different. Let's see how the 6z GEFS pans out. I love this run we have systems all approaching from the southwest.... It pulls in deep arctic air via Gorge/Columbia Basin. Any moisture would be snow. This might come back to bite me, but I have 55-60% confidence we at least see a modified blast, and a 28-35% chance of a significant regional blast, perhaps in long duration.

[Heavy Snow]

Crazy pattern at day 15. The trough gets flattened by the ridge.

 

http://maps1.pivotalweather.com/maps/models/gfs/2016120506/360/500h_anom.na.png

[Phil]

Lol, the best model runs always happen when I'm sleeping. So yeah, I'm liking my second half of December call right about now.

 

[Gradient Keeper]

The agreement through day 2-5 is a lock, and to see how closely 6z mirrored 00z through day 8-9 is crazy. Something HUGE is coming.

[Gradient Keeper]

Crazy pattern at day 15. The trough gets flattened by the ridge.

 

http://maps1.pivotalweather.com/maps/models/gfs/2016120506/360/500h_anom.na.png

Yeah, it's crazy PV is further west initially into northern Alberta, then rotates southeastward. Another PV lobe moves over Haida Gwaii Lol. The entire pattern after day 9 is like a crazy hybrid retrogressive pattern.

[Heavy Snow]

I've been doing this for quite a few years and I have never seen back to back runs like this be so close to delivering not just a true regional arctic blast, but possible historic cold. I'm not counting 2008 or events that actually panned out. The potential is off the charts coming up after day 6. Usually after we see one amazing, incredibly cold run with a massive arctic blast/snow we see the very next run either watering it down or completely different. To see this on consecutive runs means something, and I believe something big is coming. And to see this before day 10 only increases my confidence. Of course the odds are against it I'm sure, but when are they not. This seems different. Let's see how the 6z GEFS pans out. I love this run we have systems all approaching from the southwest.... It pulls in deep arctic air via Gorge/Columbia Basin. Any moisture would be snow. This might come back to bite me, but I have 55-60% confidence we at least see a modified blast, and a 28-35% chance of a significant regional blast, perhaps in long duration.

 

Yeah to me this Winter feels totally different from previous ones. Your right about consecutive runs showing Arctic Blast over and over again, never seen that to this degree ever. If we are ever going to have a Winter like we use to have back in the good old days, this is definitely the season it can happen. A lot of things still have to line up just right but all the ingredients are there for it to happen.

[Phil]

Last two GFS runs really attempt at this.

 

So..here's how mid/late December could overperform all expectations, via a troposphere/stratosphere PV coupling right over west/central Canada.

 

Some modeling (including the 12z GFS/GEFS) sends WAFz into the stratPV via the NATL, following the ongoing CW event. So, mass flux increases upon propagation into western Eurasia, and an appendage of the PV strengthens over west/central Canada following the wave2 cycle response.

 

So, when we cycle from wave2 back into wave1, the dominant PV lobe consolidates over western Canada, while the Eurasian portion of the PV gets blasted. So, via that GOA/EPO ridge, the big vortex in west/central Canada can couple with the PV there while the wave1/MT shot out of Eurasia bombards the polar domain with WAFz/blocking, forcing the entire lower PV column into western Canada.

 

http://i724.photobucket.com/albums/ww243/phillywillie/Mobile%20Uploads/5309EB33-342B-4F03-890F-10DB6F57E9D0_zpsdptzbzow.jpg

 

Then we'd have a mostly coupled PV sitting somewhere in the vicinity of Alberta, possibly ready to unload over the region if we can keep wave driving/blocking going. So while we'd be playing with possible +EPO fire if the wave driving fails, it could also turn into something historic if everything is of sufficient amplitude and is timed properly.

[Gradient Keeper]

6z GEFS Ensembles were.................

[Gradient Keeper]

Excellent! HUGE improvement. Something BIG is coming

[Gradient Keeper]

6z GFS Composite Analogs

Day 6-10, 8-14

Looking good, and the correlation score is increasing. Something HUGE is coming!

 

 

Day 6-10

 

http://www.cpc.ncep.noaa.gov/products/predictions/short_range/tools/gifs/500hgt_comp_06gfs610.gif

 

 

Day 8-14

 

http://www.cpc.ncep.noaa.gov/products/predictions/short_range/tools/gifs/500hgt_comp_06gfs814.gif

[MossMan]

Currently 34 degrees...waiting for the moisture to arrive...and WOW with both the 00z and 6z!!

[Gradient Keeper]

6z GFS Ensembles

Definitely improvement. Ensemble mean down and many cold members.

 

 

Portland

http://old.wetterzentrale.de/pics/MT8_Portland_Oregon_USA_ens.png

 

 

Seattle

http://old.wetterzentrale.de/pics/MT8_Seattle_USA_ens.png

 

 

Vancouver, BC

http://old.wetterzentrale.de/pics/MT8_Vancouver_Kanada_ens.png

[westcoastexpat]

This could be a December to remember. Just like the old days we dream about. 

 

'08 was the "old days"?

 

D**n, now I feel old... 

[ShawniganLake]

Snowing here. About 1/2" so far. Temp warmed from 28 to 32 as the precip arrived.

[westcoastexpat]

Snowing here. About 1/2" so far. Temp warmed from 28 to 32 as the precip arrived.

 

Not a lot of wiggle room right now across the sub. Thread the needle right now.

[Gradient Keeper]

IR Loop update

Check out this 12 hour Loop. Watch our GOA/Alaskan Block right at 50 N, 151/150 W. Note the clockwise flow. I see very little if any movement of the block. It's almost like it is trying to hold firm more than modeled.

 

Fairbanks, AK NWS "The short term solutions last week did a great job in developing the ridge over Siberia and moving it over mainland Alaska this weekend. For the short term all the solutions keep ridging over the interior with it gradually sliding out to the east later in the week." 

 

Gradually sliding out to the east later in the week sounds different than what we see on models show it moving east much sooner by tonight and Tuesday. If the ridge were to only gradually move east that could be a game changer. The IR Loop I showed you seems to show exactly that, very little eastward progression. Perhaps the weak, stretching frontal boundary at 160 W is not strong enough to do so. I think it's something to keep an eye on.

http://www.atmos.washington.edu/images/ir_enhanced/201612051200.gif

http://www.atmos.washington.edu/~ovens/wxloop.cgi?ir_enhanced+25

[MR.SNOWMIZER]

I can't believe the 06z followed the 00z so closely. Something big is f in coming.

[Gradient Keeper]

I can't believe the 06z followed the 00z so closely. Something big is f in coming.

I can't believe it's not butter.

[Gradient Keeper]

 -Model Countdown-
Next up....
*12z NAM in 45 minutes
12z GFS in 2 hours 28 minutes
12z GEM in 3 hours 28 minutes
12z ECMWF in 4 hours 45 minutes
All eyes on Wednesday - Thursday with the potential snow/ice event, big east wind storm, and then of course days 5-8 upstream over Alaska with the Block and up in the NWT with the PV moving into northern AB/BC. Incredible potential for a real-deal legitimate blast in the 6-10 day period.

[Jbolin]

Had some light flurries here about 10 mins. ago, brief break now but more precip inbound shortly. 

I also live at the highest point in W. Seattle ( 532 ft )

[snow maniac]

Snow mix at 300 feet in Mason County

[FroYoBro]

Temperatures are unimpressive even for a onshore shower pattern like this. Have a little southern breeze going on. 

[catnip]

First decent snowfall in years, right around 2" so far.

[Phil]

First decent snowfall in years, right around 2" so far.

That's just..perfect.

[Geos]

First decent snowfall in years, right around 2" so far.

That's awesome. Wet snow was falling here. No accumulation yet.

[TT-SEA]

Temperatures are unimpressive even for a onshore shower pattern like this. Have a little southern breeze going on. 

 

 

Feeling like the NAM had a better handle on the air mass this morning.  

[FroYoBro]

Looks like the coast range is getting some good sticking snow with this band that is approaching. It will probably be mostly rain here.  

[Kayla]

If Portland is going to see any sticking snow, between now and 10am looks to be the window. Cold front is pushing over the coast range now with snow falling and sticking at 200'.

[MikeInEverett]

Woke up to light rain..

[BLI snowman]

Not looking too promising, air is pretty saturated already and temps aren't close (36 here at about 300'). Hard to see us getting below 34.

[FroYoBro]

Not looking too promising, air is pretty saturated already and temps aren't close (36 here at about 300'). Hard to see us getting below 34.

I'm starting to wonder if I will even see many snowflakes down here in the Tigard/Beaverton area. Just seeing light rain right now. 

[Timmy]

37 and rain in scappoose

[BLI snowman]

I'm starting to wonder if I will even see many snowflakes down here in the Tigard/Beaverton area. Just seeing light rain right now. 

 

I'd imagine you'll see plenty, the band will drop the temp, but accumulations are going to be tough from this one. Temp needs to drop several degrees before 10am. 

 

Manning in the eastern coast range is at 492' and has cooled a half degree in the past half hour

 

https://www.wunderground.com/personal-weather-station/dashboard?ID=KORBANKS1#history/tdata/s20161205/e20161205/mdaily

[luminen]

First decent snowfall in years, right around 2" so far.

 

Looks pretty much the same here. Finally some snow. Drivers in snowy weather scare me in the PNW.

[snow maniac]

Snow mix at 300 feet in Mason County

All snow, good 1/2 inch already now.

[crf450ish]

Looks pretty much the same here. Finally some snow. Drivers in snowy weather scare me in the PNW.

Only in the western half of the PNW....where so much time elapses between snows that they all forget how to drive in it 

[MossMan]

Lumpy rain! 34 degrees!

[HighlandExperience]

Lumpy rain! 34 degrees!

Too dam warm #warningshot