December 2014 Observations for the Pacific Northwest

[snow_wizard]

Very impressive gradients through southern BC and northern WA on this run. Bellingham could get blasted with some strong winds.

[Snow]

There's going to be at least one lucky city up and down the I-5 corridor that will get some decent snow accumulations.

[snow_wizard]

Looks like 850s drop to about -10 over the East Puget Sound lowlands. It looks like this will qualify as an Arctic outbreak.

 

Another thing to bear in mind is it's obvious the GFS has picked on something new on this run, since the trough digs a bit further west. Still time for it to improve even more.

[bainbridgekid]

Had to update map... grabbed 12 hour precip on 12Z run.  

 

Still not bad.

That's an impressive improvement. It will be interesting to see if the increase in moisture translates to the WRF.

 

I still think this has potential to be similar to 11/29.

[HighlandExperience]

Looks like 850s drop to about -10 over the East Puget Sound lowlands. It looks like this will qualify as an Arctic outbreak.

 

There will be snow from Portland to Mt. Vernon. 

[Bham_Guy]

Very impressive gradients through southern BC and northern WA on this run. Bellingham could get blasted with some strong winds.

 

I'd be pretty happy to see even a half inch, even if it does blow away a few hours later.

[jaya]

HR 60 Op It could just be me, but appears block is tilting more into Yukon

 

The block tilting toward Yukon will spill more cold air just off shore and give some low development. The various models pick up on this type of feature but typically mishandle the amount of development that can take place.

[Snow]

[Gradient Keeper]

The block tilting toward Yukon will spill more cold air just off shore and give some low development. The various models pick up on this type of feature but typically mishandle the amount of development that can take place.

Exactly

[jaya]

There will be snow from Portland to Mt. Vernon. 

Probably not a lot...but an inch or so isn't out of the question.

[jaya]

I'd be pretty happy to see even a half inch, even if it does blow away a few hours later.

Looking at the gradients, any snow you get will be between Bellingham and Orcas Island in the Salish sea.

[HighlandExperience]

Probably not a lot...but an inch or so isn't out of the question.

 

Won't take much to shut down Seattle. I really want Monday off work. 

[jaya]

Did you mean 0z?

 

I see it is a hair further west. Any little difference could be a big deal. At first I thought the chances were slim for snow with the initial cold shot, but now it appears there is a chance.

Very small differences in the over water trajectory will impact low development and the strength of any arctic front in the interior.  No one should hold out hope...no mater what the models look like, until the event is nearly underway. 

[jaya]

Won't take much to shut down Seattle. I really want Monday off work. 

Well, I don't know about shutting Seattle down with an inch - unless people decide to start driving in normal Seattle fashion.  But then you can do that with a light drizzle around here.

[Gradient Keeper]

Uh oh ....

 

http://www.tropicaltidbits.com/analysis/models/gfs/2014122700/gfs_z500a_namer_26.png

[jaya]

The Der Niederschlag is the most important chart I've seen today!  http://www.wetterzentrale.de/pics/MT8_Seattle_USA_ens.png. All cold and tight in the short term (don't worry about the long term -- too far out especially for the operational dumb-down GFS beyond 192.

[Guest Winterdog]

Won't take much to shut down Seattle. I really want Monday off work. 

You must be a school teacher.

[Gradient Keeper]

Parallel has the Desert SW low ejecting much faster to the east

[jaya]

Uh oh ....

 

Certainly a plausible solution as the ridge tries to retrograde and pinch off.  The parallel run does not do this: http://www.tropicaltidbits.com/analysis/models/?model=gfsp&region=namer&pkg=z500_mslp&runtime=2014122700&fh=120but seems to lose some southward punch of the short wave...and that would track energy eastward along the Canadian border and keep things mild and onshore in the PNW.

[bainbridgekid]

You must be a school teacher.

Pretty sure schools are all closed this week.

[Gradient Keeper]

HR 168 Parallel ... Not happening guys

 

http://www.tropicaltidbits.com/analysis/models/gfsp/2014122700/gfsp_z500a_namer_29.png

[jaya]

Second cold shot is not a lock...http://www.tropicaltidbits.com/analysis/models/?model=gfsp&region=namer&pkg=z500_mslp&runtime=2014122700&fh=150&xpos=0&ypos=0. But, at least we are looking at another arctic in the short term and had something in November.  Two in a year with a neutral-warm ENSO isn't bad.

[richard mann]

Uh oh .... http://www.tropicalt...0a namer 26.png

.. I'd say, not all that likely, with the more over-all propensity of cold movement through 'til then.

 

— As I see things, slowing east while still being in general regress more northward until about then. Leastwise the bite more SW with looking at cold's more over-all recession. While where looking at the the main gut of more primary cold air mass (depicted.) still north, it's likely not moving that far east at least quite so soon.

[Guest Winterdog]

Pretty sure schools are all closed this week.

That's right! I sure should have known that with all the kids around this week.

[Guest Winterdog]

The reload seems to have stalled just after hour 168 on the GFS normal.  Much better on the Para.

[GHweatherChris]

That's an impressive improvement. It will be interesting to see if the increase in moisture translates to the WRF.

 

I still think this has potential to be similar to 11/29.

nope

[epiceast]

the WRF does show basin floor accumulations

[Gradient Keeper]

HR 222

 

http://www.tropicaltidbits.com/analysis/models/gfsp/2014122700/gfsp_mslp_wind_wus_38.png

 

http://www.tropicaltidbits.com/analysis/models/gfsp/2014122700/gfsp_mslp_wind_namer_38.png

[HighlandExperience]

You must be a school teacher.

 

Nah.

[TT-SEA]

the WRF does show basin floor accumulations

 

 

Total snow from now until Monday afternoon per 00Z WRF... this maps seems to actually know where the mountains are located!

 

http://www.atmos.washington.edu/mm5rt/data/current_gfs/images_d3/snow72.72.0000.gif

[epiceast]

Total snow from now until Monday afternoon per 00Z WRF... this maps seems to actually know where the mountains are located!

 

http://www.atmos.washington.edu/mm5rt/data/current_gfs/images_d3/snow72.72.0000.gif

A solid 1/2" is better than none!

[Guest Winterdog]

Total snow from now until Monday afternoon per 00Z WRF... this maps seems to actually know where the mountains are located!

Thanks for that little cheering up.

[TT-SEA]

I think for Seattle this one has the possibility of failing to produce snow and also failing to deliver a high below freezing given the sunshine this week.    

 

Seriously doubting any meaningful second shot.

[Deweydog]

How do you tell the difference between an actual warning shot and a shot by someone/something with really bad aim?

[Gradient Keeper]

Your left butt cheek and Snow's gut should have a conversation.

LOL

[Gradient Keeper]

HR 84 GEM for PDX is colder than any other model

 

http://www.tropicaltidbits.com/analysis/models/gem/2014122700/gem_T850_nwus_15.png

[MossMan]

I think for Seattle this one has the possibility of failing to produce snow and also failing to deliver a high below freezing given the sunshine this week.    

 

Seriously doubting any meaningful second shot.

Between this post and your avatar, this was just a double dose of sadness!

[Gradient Keeper]

Digs trough further west than GFS

 

http://www.tropicaltidbits.com/analysis/models/gem/2014122700/gem_z500_vort_nwus_13.png

[Bryant]

I think for Seattle this one has the possibility of failing to produce snow and also failing to deliver a high below freezing given the sunshine this week.

 

Seriously doubting any meaningful second shot.

Well, last time you wrote off the models turning cold, things improved within 12 hours. Thanks

[Bryant]

Digs trough further west than GFS

 

http://www.tropicaltidbits.com/analysis/models/gem/2014122700/gem_z500_vort_nwus_13.png

Not a good trajectory for myself and others up north unfortunately.