December 2016 Observations and Model Discussion for the Pacific Northwest

[TT-SEA]

Snowing in Green Bay on the Packers game... fun to watch.

[luvssnow_spokane]

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.

So you're saying we have a chance!?

[VancouverIslandSouth]

I like the purples near Shawnigan lake.

 

I think 4"+ for that area is a pretty safe bet at this point. None of the runs are showing moisture as being an issue and your area will be cold enough for snow the entirety of the event. Victoria is more marginal, but the progression of this latest event looks better.

[MossMan]

Radar shoving the pscz towards Arlington now!!

Had a quick ALL SNOW shower while picking out our tree...magical!!!!

[Front Ranger]

Snowing in Green Bay on the Packers game... fun to watch.

 

Also dumping in Chicago.

[Trainwreck]

Had a quick ALL SNOW shower while picking out our tree...magical!!!!

Uhhhhhhh.........

[Gradient Keeper]

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.

Sounds potentially exciting. Thanks for the outstanding detailed insight.

[Phil]

So you're saying we have a chance!?

There's a chance you might.

[Phil]

Sounds potentially exciting. Thanks for the outstanding detailed insight.

Thanks, no problem.

[Deweydog]

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.

Transparent.

[TT-SEA]

Middle of the day and its all snow here.    Started out as sleet and has now switched over.

 

A c-zone over downtown Seattle this evening could make for an interesting scene at the Seahawks game.

[Front Ranger]

18z NAM simulated radar. Shows a heavy snow band up the I-5 corridor around 8am tomorrow morning.

 

[Phil]

Transparent.

Lol. The GGEM ensembles show how it could all fail and morph into 1999/00 repeat. Oh noes!

 

http://i724.photobucket.com/albums/ww243/phillywillie/Mobile%20Uploads/6EE600F2-12A6-4AE3-B4E9-23FC7CA7E192_zpsrxibui08.png

[Timmy]

Middle of the day and its all snow here. Started out as sleet and has now switched over.

 

A c-zone over downtown Seattle this evening could make for an interesting scene at the Seahawks game.

Partly cloudy and 39

[Heavy Snow]

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.

 

January 1950 historic. 

[TT-SEA]

18z NAM simulated radar. Shows a heavy snow band up the I-5 corridor around 8am tomorrow morning.

 

namsnow.gif

 

 

Guessing there is going to be a issue with school here tomorrow.

[Front Ranger]

Lol. The GGEM ensembles show how it could all fail and morph into 1999/00 repeat. Oh noes!

 

There was no widespread lowland snow in early December 1999. Throw it out!

[FroYoBro]

Middle of the day and its all snow here.    Started out as sleet and has now switched over.

 

A c-zone over downtown Seattle this evening could make for an interesting scene at the Seahawks game.

 

I think you are going to share some very snowy pictures with us 24 hours from now. 

[Phil]

The 12z EPS mean is an improvement over 00z. Stronger high latitude blocking and a more displaced PV/cold core into western and central North America. Could still use more amplification out of the NPAC though, as there's still too much GOA vorticity there verbatim, which sends the majority of the cold east of the Rockies.

[TT-SEA]

Continues to dump snow here and its accumulating again.  

[Timmy]

Continues to dump snow here and its accumulating again.

Congratufrickenlations

[TT-SEA]

[crf450ish]

Graupel coming down here while the radar says rain. Not going to complain. The temp has started to fall every so slowly the last hour. Looking forward to the onset of colder temps as we enter this new pattern. 

[Deweydog]

The 12z EPS mean is an improvement over 00z. Stronger high latitude blocking and a more displaced PV/cold core into western and central North America. Could still use more amplification out of the NPAC though, as there's still too much GOA vorticity there verbatim, which sends the majority of the cold east of the Rockies.

 

Seems to be the general theme is that the Pacific is fighting like mad to stay open for business.  Keeps us in a position of trying to hold cold patterns together with duct tape and bungee cords.  

[Bryant]

Continues to dump snow here and its accumulating again.

Most you've posted in weeks, pretty convenient I'd say

[Phil]

Seems to be the general theme that the Pacific is fighting like mad to stay open for business. Keeps us in a position of trying to hold cold patterns together with duct tape and bungee cords.

Haha, that's an eloquent way of putting it, but yeah there's still that underlying systematic tendency to put a trough in the GOA domain. It'll be a fight all winter to keep that subdued unless we can get more persistent subsidence along/west of 120E in the tropics.

[Cold front]

Omak went from a calm 40 to 35 the last hour with 35 mph winds.

[TT-SEA]

Most you've posted in weeks, pretty convenient I'd say

 

 

People post more when there is winter weather to talk about.    I think you know that.   

[FroYoBro]

Most you've posted in weeks, pretty convenient I'd say

 

Congratufrickenlations

We should definitely mock people who post snow pictures on a weather forum. 

[Bryant]

We should definitely mock people who post snow pictures on a weather forum.

No mockery, just an observation! It's what we do on weather forums!

[Goducks09]

Long time listener, first time caller here.  ;-)  Excited for the upcoming winter weather!  Will provide observational updates from downtown PDX.  47 degrees and partly cloudy for now...just waiting on the fun.  Cheers all!

[TT-SEA]

We should definitely mock people who post snow pictures on a weather forum. 

 

 

I actually love Timmy's snow pics from North Plains.     Can't wait to see some tomorrow.

[Timmy]

I actually love Timmy's snow pics from North Plains. Can't wait to see some tomorrow.

Haha, I just wish this forum was easier to upload pics to. I hope I have some decent ones to post tomorrow.

Just had a super light shower pass by. Just chunky rain!

[Timmy]

Latest nam looks decent.

 

http://www.tropicaltidbits.com/analysis/models/?model=nam4km&region=nwus&pkg=asnow&runtime=2016120418&fh=45&xpos=0&ypos=261

[Gradient Keeper]

18z GFS
Begins in.... 2 minutes

Think snow!!!! I would like to see the cold air persist a bit longer, then I am real interested in seeing the 6-10 day period as well if Ensembles continue to trend colder. Yeah, it's the 18z, but the Drunk Uncle can still be utilized for some things. He'll probably need a Breathalyzer test after this run.

Feel free to play along (You may need to refresh pages)
Northwest view - http://www.tropicaltidbits.com/analysis/models/?model=gfs&region=nwus&pkg=mslp_pcpn_frzn&runtime=2016112912&fh=0&xpos=0&ypos=197
North America view - http://www.tropicaltidbits.com/analysis/models/?model=gfs&region=namer&pkg=z500_mslp&runtime=2016112912&fh=0&xpos=0&ypos=197
North Pacific view - http://www.tropicaltidbits.com/analysis/models/?model=gfs&region=npac&pkg=z500_mslp&runtime=2016112912&fh=0&xpos=0&ypos=197
Alaska view - http://www.tropicaltidbits.com/analysis/models/?model=gfs&region=ak&pkg=T850&runtime=2016112912&fh=0&xpos=0&ypos=197

[TT-SEA]

Haha, I just wish this forum was easier to upload pics to. I hope I have some decent ones to post tomorrow.

Just had a super light shower pass by. Just chunky rain!

 

 

I upload them just fine... save them to computer and then upload through an image hosting site and copy the URL.

 

I have never been able to upload them directly from my phone though.  

[jcmcgaffey]

Winter storm watch just issued for SEA starting tomorrow evening.

[Front Ranger]

Seems to be the general theme is that the Pacific is fighting like mad to stay open for business.  Keeps us in a position of trying to hold cold patterns together with duct tape and bungee cords.  

 

That goes for 96.8% of winters.

[Timmy]

Yeah I don't really want to use my computer though. Or an image hosting site.

[Bryant]

Haha, I just wish this forum was easier to upload pics to. I hope I have some decent ones to post tomorrow.

Just had a super light shower pass by. Just chunky rain!

Either view the forum as desktop mode from your phone, or upload to imgur.com and use that link