December 2016 Observations and Model Discussion for the Pacific Northwest

[PV=nRT]

This morning is the first time I have had a sub 40F temperature this season and it is appearing the max will also be sub 40F.  With a little clearing tonight I may also reach 32F for the first time.  My station is located about 10 miles south of downtown Portland.  

[kokaneekidz]

Yeah definitely some good returns out there - too bad the Olympics will eat most of it up. Maybe once the low moves south a little more maybe we can get a better flow to bring showers into Puget Sound area.

That is the trouble in this flow pattern. Seattle and environs becomes a downsloping rainshadow/ Need the flow to turn nw erly to fill in the area with precip. Hope tonight is generous to us all.

[Bryant]

FWIW, 18z GFS cut back significantly on the amount of precip over the next 24 hours when compared to 12z.

 

Might not be picking up small-scale stuff like CZ, but thought I'd share nonetheless.

 

 

 

EDIT: G-Sax beat me to it.

 

You've been providing excellent analysis throughout this event, thank you very much

[Prairiedog]

The JMA was one of the first models to see this current modified Arctic Blast so let's revisit what it's showing us in it's updated 12z run today. Good pattern setting up. We are close at days 7 and 10.

 

http://img.meteocentre.com/models/jma_amer_12/GZ_D5_PN_168_0000.gif

http://img.meteocentre.com/models/jma_amer_12/TT_GZ_UU_VV_168_0850.gif

http://img.meteocentre.com/models/jma_amer_12/GZ_D5_PN_240_0000.gif

http://img.meteocentre.com/models/jma_amer_12/TT_GZ_UU_VV_240_0850.gif

"good" pattern setting up, "close".  Big change from they hyperbole that its a certainty, epic, arctic outbreak of the ages, gonna happen talk.  As excited and as much as we "wish" and "want" it to happen, lets get it inside of 5-6 days then we can get excited.  Even within that time frame it's not a guarantee.  I'm sure as heck hoping it will happen.  But lets stay the course and wait and see.  It's the PNW and climo is NOT our friend.  hope it happens but too early to call it yet.

[Bryant]

"good" pattern setting up, "close".  Big change from they hyperbole that its a certainty, epic, arctic outbreak of the ages, gonna happen talk.  As excited and as much as we "wish" and "want" it to happen, lets get it inside of 5-6 days then we can get excited.  Even within that time frame it's not a guarantee. 

 

lol

[Kayla]

Sure it's a long shot. Even having a dusting going into a cold, clear night is nice though.

 

That heavy batch of precip not giving you anything?

 

Been getting pretty heavy snow here now for the last couple hours. Line has just been training right over me.

[MikeInEverett]

Ouch glad it's one run

 

Yeah it's one run, but it's also the last GFS run before things start developing tonight.. So it's definitely something to take notice of.

[Phil]

Phil, what do you see the PV doing? With the high latitude blocking you see it moving poleward?

Well it's going to be strengthening in the upper levels but will remain perturbed in the lower levels despite the -WPO (favors stronger PV and rising AO). Key is to avoid a complete vertical coupling.

[BLI snowman]

Andrew must be getting clobbered.

[kokaneekidz]

Let's hope that D**n WSW issued by the NWS isn't going to screw us again! 

It's as if the nws just can;t be quiet about their pocket aces ...They get cocky. Then low and behold someone beats em with a seven duece.... Just be quiet and humble or be shown who's boss by mother nature. Jeez will people ever learn.

[Front Ranger]

Flatiron did bequeath to us the knowledge that 96.8% of the time the Pacific ALWAYS wins.

 

69% of the time, I'm always right.

[Phil]

Ouch, the 12z EPS mean is ugly in the extended range. Way too much -WPO/+EPO hence a stronger systematic coupling w/ the PV. Western 2/3rds of the nation ends up blowtorching under the Alaskan vortex.

[kokaneekidz]

If the NWS could please just drop the WSW and then in just a short time like magic the pscz will begin in earnest.. Pretty please with a maraschino cherry on top. Thanks, residents of western washington and environs/

[Front Ranger]

Ouch, the 12z EPS mean is ugly in the extended range. Way too much -WPO/+EPO hence a stronger systematic coupling w/ the PV. Western 2/3rds of the nation ends up blowtorching under the Alaskan vortex.

 

Yep, pretty bad. That being said, the models have been flailing wildly in the long range the past few days.

[MR.SNOWMIZER]

Ouch, the 12z EPS mean is ugly in the extended range. Way too much -WPO/+EPO hence a stronger systematic coupling w/ the PV. Western 2/3rds of the nation ends up blowtorching under the Alaskan vortex.

Overrated.

[Phil]

Yep, pretty bad. That being said, the models have been flailing wildly in the long range the past few days.

Yeah, definitely have seen that windshield wiper effect in the extended range. Still, it's a fragile game because a broad/flat NPAC anticyclone and/or -WPO will strengthen and align the PV while an amplified wavebreaking regime will tilt/perturb the PV from underneath. Can be the difference between a baratropic PV and a baroclinic one..

[HighlandExperience]

Awesome video of the snow near Vancouver, BC.

 

https://twitter.com/CaminoMyWay/status/805885908855623681

Jealous !

[SilverFallsAndrew]

I have about 3.5" of new snow today. Currently light snow and 32 degrees. 33/30 so far on the day. 

[Prairiedog]

This morning is the first time I have had a sub 40F temperature this season and it is appearing the max will also be sub 40F.  With a little clearing tonight I may also reach 32F for the first time.  My station is located about 10 miles south of downtown Portland.  

Me too.  Went from 36f overnight to 34f and hung there till about 11am when the rain turned over to snow.  Sitting at 32f since.  Off Springwater near Fischers Mill/Redland area.

[Phil]

18z GFS taking on a flatter look over the NPAC again.

[kokaneekidz]

Awesome video of the snow near Vancouver, BC.

 

https://twitter.com/CaminoMyWay/status/805885908855623681

Will that be us in a mere 6 hours from now? Do we feel worthy??

[luvssnow_spokane]

Me too.  Went from 36f overnight to 34f and hung there till about 11am when the rain turned over to snow.  Sitting at 32f since.  Off Springwater near Fischers Mill/Redland area.

 

 

I went from a low of 34 @ 8:10am this morning to the current high of 38.5. I am hoping to stay under 40 today. 

[Heavy Snow]

"good" pattern setting up, "close".  Big change from they hyperbole that its a certainty, epic, arctic outbreak of the ages, gonna happen talk.  As excited and as much as we "wish" and "want" it to happen, lets get it inside of 5-6 days then we can get excited.  Even within that time frame it's not a guarantee.  I'm sure as heck hoping it will happen.  But lets stay the course and wait and see.  It's the PNW and climo is NOT our friend.  hope it happens but too early to call it yet.

 

Yeah, definitely wait and see but there is too much ensemble support from the models for us not to see a modified Arctic Blast. One that should be colder than this one we're in. 3 straight great GFS runs and I have a feeling we are going to see a 4th one with the updated run of the 18z GFS.

[Deweydog]

I thought we were at when not if?

[Heavy Snow]

Huge 564 dam Block in SW Alaska at day 8. I like where the 18z GFS is headed. 

 

http://maps1.pivotalweather.com/maps/models/gfs/2016120518/192/500h_anom.na.png

[luvssnow_spokane]

18z wants to send us the goods next Tuesday

 

 

 

 

 

[Heavy Snow]

Arctic Front drops down per 18z GFS at day 9.

 

http://maps1.pivotalweather.com/maps/models/gfs/2016120518/216/500h_anom.na.png

http://maps1.pivotalweather.com/maps/models/gfs/2016120518/216/850th_nb.na.png

[PV=nRT]

The models have done a reasonable job with the current pattern.  As expected with any pattern change there is usually a lot of noise in the models as they strive to converge, or not converge, on a similar solution.  As a result there is a lot of back and forth in solutions, and there will continue to be volatility as we go forth.  The northern and southern streams will fight it out for dominance.  The pattern of digging energy back over the Pacific is not unheard of as there is a lot of cold air up north.

 

That said this is also a pattern that could, and I emphasize could deliver significant snows to our area as southern stream systems cruise by to the south advecting copious amounts of moisture potentially over a very cold air mass.  It all depends of how the two streams interact and which if either is more dominate.  I enjoy snow and cold and as many of us are here rooting for the snowier scenario.  Expect more flipping of the models and do not get too caught up in either scenario.  Just keep in mind weather forecasting is not an exact science.  This is setting up to be an interesting winter much more so than the past several winters.

 

Oh...and it always helps to keep your fingers crossed and your lawn mowed to its lowest setting!

[westcoastexpat]

Jealous !

 

Yup. It's been AWESOME. 

[kokaneekidz]

18z wants to send us the goods next Tuesday

 

gfs_T850_namer_33.png

That looks very similar to the setup from 1996. I see the wraparound cold is much stronger than today's. Probably ocean temps will be a couple degrees cooler next week as well to aid in cooling.

[Heavy Snow]

The models have done a reasonable job with the current pattern.  As expected with any pattern change there is usually a lot of noise in the models as they strive to converge, or not converge, on a similar solution.  As a result there is a lot of back and forth in solutions, and there will continue to be volatility as we go forth.  The northern and southern streams will fight it out for dominance.  The pattern of digging energy back over the Pacific is not unheard of as there is a lot of cold air up north.

 

That said this is also a pattern that could, and I emphasize could deliver significant snows to our area as southern stream systems cruise by to the south advecting copious amounts of moisture potentially over a very cold air mass.  It all depends of how the two streams interact and which if either is more dominate.  I enjoy snow and cold and as many of us are here rooting for the snowier scenario.  Expect more flipping of the models and do not get too caught up in either scenario.  Just keep in mind weather forecasting is not an exact science.  This is setting up to be an interesting winter much more so than the past several winters.

 

Oh...and it always helps to keep your fingers crossed and your lawn mowed to its lowest setting!

 

I want to be in the middle of that Winter Battle Zone!

[Phil]

18z GFS looks great in the clown range again but really playing with fire upstream. Will probably finish with an Alaskan low/+EPO given the progression verbatim, but that's really not worth paying attention to at this point.

[seattleweatherguy]

Steady rain in bothell

[Prairiedog]

I think it was '96 that a convergence zone set up over the general Portland area.  It was a Sunday morning with light rain and about 42f.  By noon it switched to snow and the temp dropped all day.  Blowing, drifting snow most of the day winds wipping around 25-30mph.  Ended up at 18f when the snow stopped and 6" of powder on the ground in Oregon City.  I was teaching and we missed about a week of school.  Stars came out that night and I had a low of 14f.  It was magnificent!  Closest to a nor'easter I've seen here. 

[EA_TTD]

"Clown range" brought it's A-game today.

 

 

http://maps1.pivotalweather.com/maps/models/gfs/2016120518/312/500h_anom.na.png

[luvssnow_spokane]

Just for grins and giggles the 18z GFS keeps us cold and snowy from the 12th to the 21st of December... Not that it means a D**n thing but great for delusional thinking.

[Parksvillewx]

This little fella has been parked over me for the last hour or so. Been dumping snow since. Starting to accumulate.

 

[Goducks09]

I think it was '96 that a convergence zone set up over the general Portland area.  It was a Sunday morning with light rain and about 42f.  By noon it switched to snow and the temp dropped all day.  Blowing, drifting snow most of the day winds wipping around 25-30mph.  Ended up at 18f when the snow stopped and 6" of powder on the ground in Oregon City.  I was teaching and we missed about a week of school.  Stars came out that night and I had a low of 14f.  It was magnificent!  Closest to a nor'easter I've seen here. 

 

Seems so mystical to hear stories like this nowadays.  We haven't seen anything like this in quite some time...

[kokaneekidz]

Well, NWS just canceled the Winter Storm Watch and replaced it with a Winter Weather Advisory. Calling for a trace-1 inch, maybe up to 3 with any CZ.

 

Now we are in business! Got that stupid WSW outta' the way so now a CZ will definitely set-up. 

Maybe they are following our advice. lol

[Heavy Snow]

4 straight runs now of the GFS showing the goods. Now we need to see a 5th straight run tonight with the 00z GFS and hope that the GEM and KING EURO will follow.