December 2014 Observations for the Pacific Northwest

[SilverFallsAndrew]

Looks pretty D**n cold for Vegas early next week. January 2013 redux???

People said I was trolling a week ago when I said a Jan 2013 redux was on the table.

[Deweydog]

People said I was trolling a week ago when I said a Jan 2013 redux was on the table.

 

When you speak of essentially snowless chilly periods, best you take cover.  

[SilverFallsAndrew]

18z goes nowhere good in the long range. Oh well...

[Gradient Keeper]

18z GFS

Op/Parallel much colder than 12z through HR 174 ....

Op Long Range = No reload through HR 240 ...

Parallel Long Range = Very similar to both 12z GFS/ECMWF with retrogression and possible major reload after day 9-10..

 

HR 210 Mega-Herculean strength arctic front

http://www.tropicaltidbits.com/analysis/models/gfsp/2014122418/gfsp_z500_mslp_namer_36.png

http://www.tropicaltidbits.com/analysis/models/gfsp/2014122418/gfsp_z500a_namer_36.png

HR 234

http://www.tropicaltidbits.com/analysis/models/gfsp/2014122418/gfsp_z500_mslp_namer_40.png

[Gradient Keeper]

http://www.tropicaltidbits.com/analysis/models/gfsp/2014122418/gfsp_z500a_namer_40.png

[Gradient Keeper]

HR 240 Day 10

HOLY CRAP

 

http://www.tropicaltidbits.com/analysis/models/gfsp/2014122418/gfsp_z500_mslp_namer_41.png

 

http://www.tropicaltidbits.com/analysis/models/gfsp/2014122418/gfsp_z500a_namer_41.png

[SilverFallsAndrew]

When you speak of essentially snowless chilly periods, best you take cover.

We could do a lot worse!

[SilverFallsAndrew]

HR 240 Day 10

HOLY CRAP

 

http://www.tropicaltidbits.com/analysis/models/gfsp/2014122418/gfsp_z500_mslp_namer_41.png

 

http://www.tropicaltidbits.com/analysis/models/gfsp/2014122418/gfsp_z500a_namer_41.png

Just wet myself.

[IbrChris]

That is an impressive shortwave moving through BC!

[IbrChris]

There have been some serious hints at some sort of modified blast around New Years or a bit thereafter on several runs now. 00z Euro yesterday morning had it...GFS ensembles took a tumble overnight with nearly half latching on to some sort of cold scenario with the mean close to -5c. Will be interesting to see if we manage the retrogression necessary to get the job done, or if we see a couple weeks of mainly Gorge-driven low-level chill. The pattern is flirting with something memorable.

[luvssnow_spokane]

HR 240 Day 10

HOLY CRAP

 

http://www.tropicaltidbits.com/analysis/models/gfsp/2014122418/gfsp_z500_mslp_namer_41.png

 

http://www.tropicaltidbits.com/analysis/models/gfsp/2014122418/gfsp_z500a_namer_41.png

Oh look 10 days out again.. Rinse repeat until March

[IbrChris]

Let's break down the ensembles today:

12z GFS
D 6-10: Ridge centered off BC coast near 50N-140W. Chilly...NE flow aloft...Arctic air oozing across divide/south from BC into Columbia Basin.
D 11-15: Nearly 70% of members have a quite favorable look with block over Alaska or in Bering Sea...at or west of 150W. 15% show the major shortwave that the 18z GFS-PARA indicates.
360 hr: 50-50 split between ridge closer to west coast and block in western AK/Bering Sea...impressive anomalies latter sol considering it's 15 days away. Would be quite cold for PNW in N-NE flow in both sols but esp the latter sol which is better supported by 11-15 day pattern.

12z ECMWF
D 6-10: Similar to GFS...ridge centered near 50N-140W. 32% of members displace ridge north into AK with more favorable NE flow over PNW. Chilly, favoring backdoor intrusion.
D 11-15: 66% ridge centered along west coast...NO block over Alaska/Bering Sea. 34% block over AK with classic arctic blast in PNW.
360 hr: 57% trof in GoA...ridge over Midwest. 42% block over Alaska, arctic blast in PNW.

12z ECMWF-EPS: Of note in 11-15 day 64% of ensembled indicative of at least a modified blast PNW, at hour 360 38% of ensembles suggest an arctic blast in the PNW based on 2-meter temp anomalues (threshold -8F dep).

12z CMC
6-10: More varied sols than GFS/Euro...66% supportive of modified backdoor blast into PNW, 33% suggest ridging too close for true blast (perhaps a tad closer than Euro/GFS).
11-15: Again all over the place...only 28% suggest an arctic blast, most members are chilly though.
360 hr: All over the place...23% indicative of arctic blast in PNW, most would still be chilly though.

A rough summary would be about 2/3 of ensemble members indicate chilly temps next 2 weeks in the PNW and about a quarter indicate something I'd consider an arctic blast.

[Tyler Mode]

I walked up the road to the top of Larch Mountain in Oregon on New Year's Day last year.  The road was closed, but even at 4,000' there was barely a dusting in some areas.  From the picture below, it looks like a spring day...

 

http://weathercrazy.smugmug.com/Landscapes/Larch-Mountain-1114/

 

http://weathercrazy.smugmug.com/Landscapes/Larch-Mountain-1114/i-rpTSVHr/0/L/83.%20G%20Hood%20V%20Wide-L.jpg

I remember hiking up 4880' Table Rock last winter on January 5th and there was virtually no snow on the trail. So I guess the snow pack is off to a better start this winter...

 

 

[SilverFallsAndrew]

Let's break down the ensembles today:

 

12z GFS

D 6-10: Ridge centered off BC coast near 50N-140W. Chilly...NE flow aloft...Arctic air oozing across divide/south from BC into Columbia Basin.

D 11-15: Nearly 70% of members have a quite favorable look with block over Alaska or in Bering Sea...at or west of 150W. 15% show the major shortwave that the 18z GFS-PARA indicates.

360 hr: 50-50 split between ridge closer to west coast and block in western AK/Bering Sea...impressive anomalies latter sol considering it's 15 days away. Would be quite cold for PNW in N-NE flow in both sols but esp the latter sol which is better supported by 11-15 day pattern.

 

12z ECMWF

D 6-10: Similar to GFS...ridge centered near 50N-140W. 32% of members displace ridge north into AK with more favorable NE flow over PNW. Chilly, favoring backdoor intrusion.

D 11-15: 66% ridge centered along west coast...NO block over Alaska/Bering Sea. 34% block over AK with classic arctic blast in PNW.

360 hr: 57% trof in GoA...ridge over Midwest. 42% block over Alaska, arctic blast in PNW.

 

12z ECMWF-EPS: Of note in 11-15 day 64% of ensembled indicative of at least a modified blast PNW, at hour 360 38% of ensembles suggest an arctic blast in the PNW based on 2-meter temp anomalues (threshold -8F dep).

 

12z CMC

6-10: More varied sols than GFS/Euro...66% supportive of modified backdoor blast into PNW, 33% suggest ridging too close for true blast (perhaps a tad closer than Euro/GFS).

11-15: Again all over the place...only 28% suggest an arctic blast, most members are chilly though.

360 hr: All over the place...23% indicative of arctic blast in PNW, most would still be chilly though.

 

A rough summary would be about 2/3 of ensemble members indicate chilly temps next 2 weeks in the PNW and about a quarter indicate something I'd consider an arctic blast.

Great info

[SilverFallsAndrew]

I walked up the road to the top of Larch Mountain in Oregon on New Year's Day last year. The road was closed, but even at 4,000' there was barely a dusting in some areas. From the picture below, it looks like a spring day...

 

http://weathercrazy.smugmug.com/Landscapes/Larch-Mountain-1114/

 

http://weathercrazy.smugmug.com/Landscapes/Larch-Mountain-1114/i-rpTSVHr/0/L/83.%20G%20Hood%20V%20Wide-L.jpg

Great pic!

[IbrChris]

I think the odds of a modified arctic blast toward/bit after New Years have increased a good deal last couple days of runs. Still a lot to iron out but nice to see something mildly interesting in the model output after a December in which I mostly perused the models because of my job (not for pleasure).

[Deweydog]

Anyone else find the whole Frosty the Snowman thing particularly sad and disturbing considered it's centered around snow melt?

[Gradient Keeper]

Let's break down the ensembles today:

 

12z GFS

D 6-10: Ridge centered off BC coast near 50N-140W. Chilly...NE flow aloft...Arctic air oozing across divide/south from BC into Columbia Basin.

D 11-15: Nearly 70% of members have a quite favorable look with block over Alaska or in Bering Sea...at or west of 150W. 15% show the major shortwave that the 18z GFS-PARA indicates.

360 hr: 50-50 split between ridge closer to west coast and block in western AK/Bering Sea...impressive anomalies latter sol considering it's 15 days away. Would be quite cold for PNW in N-NE flow in both sols but esp the latter sol which is better supported by 11-15 day pattern.

 

12z ECMWF

D 6-10: Similar to GFS...ridge centered near 50N-140W. 32% of members displace ridge north into AK with more favorable NE flow over PNW. Chilly, favoring backdoor intrusion.

D 11-15: 66% ridge centered along west coast...NO block over Alaska/Bering Sea. 34% block over AK with classic arctic blast in PNW.

360 hr: 57% trof in GoA...ridge over Midwest. 42% block over Alaska, arctic blast in PNW.

 

12z ECMWF-EPS: Of note in 11-15 day 64% of ensembled indicative of at least a modified blast PNW, at hour 360 38% of ensembles suggest an arctic blast in the PNW based on 2-meter temp anomalues (threshold -8F dep).

 

12z CMC

6-10: More varied sols than GFS/Euro...66% supportive of modified backdoor blast into PNW, 33% suggest ridging too close for true blast (perhaps a tad closer than Euro/GFS).

11-15: Again all over the place...only 28% suggest an arctic blast, most members are chilly though.

360 hr: All over the place...23% indicative of arctic blast in PNW, most would still be chilly though.

 

A rough summary would be about 2/3 of ensemble members indicate chilly temps next 2 weeks in the PNW and about a quarter indicate something I'd consider an arctic blast.

Thanks for the analysis and info, as well as taking the time to do so....

 

My take on the Operational models.

12z GFS Parallel/12z ECMWF/18z Parallel all show a modified backdoor blast before day 6. 18z through HR 174 was much colder than 12z quite chilly PDX-east. All models agree on strong retrogression after day 8 and timing moved ahead with 18z Parallel. We might be starting to see some run-to-run consistency with the Parallel how it handles day 7-10. We also may be closer to agreement before day 6. Could we even see models trend colder in the coming days? I'm encouraged, but remain cautiously optimistic as in I'm not going all-in just yet.

 

Onto 00z!

[Gradient Keeper]

[Model Countdown]
Next up....
00z NAM 1 hour 40 minutes
00z GFS 3 hours 20 minutes
00z GEM 4 hours 40 minutes
00z ECMWF 5 hours 50 minutes

[Gradient Keeper]

18z GFS 850mb Ensemble mean/members coldest yet by far.... 

[IbrChris]

Looking at Monday's weeklies I don't think the week 3-4 pattern at 500 mb is that bad for a chilly/cold PNW (maybe arctic?). On both those weeks I like the overall pattern with positive height anomalies across NW North America above 55 N and a trough over the far eastern Pacific/West Coast. Week 4 the pattern almost looks like it could give a nice blast with eastern ridging along with a block over Alaska. In short it may be a cold January in the PNW

[SilverFallsAndrew]

Well I tried to post a pic, but it wouldn't upload. I'll try again later. But anyways its a pic of slushy snow. Final tally was 2".

[IbrChris]

Sure enough when looking at clustered Euro weeklies solutions for Weeks 2-4 there's a substantial risk of arctic air throughout the period...about half the members Weeks 3-4 and 2/3 week 2 suggest a favorable pattern with N-NE flow aloft.

[richard mann]

No doubt right?

 

Right.

[Gradient Keeper]

18z GFS Ensembles 850mb temps
Before day 7 - As mentioned by far the coldest yet. Mean temps all dropped substantially over previous runs with a cluster of members below -10c. Based on this improvement over previous runs there is room for the mean temp to drop further.

 

Portland

 

Seattle

 

Vancouver, BC

[Snow]

[Snow]

[Phil]

I'm going to call BS on the weeklies after January 15th..forecasted pacific circulation doesn't fit the forcing progression at all. We're going back into a +PNA for the 2nd half of January..

[richard mann]

HR 240 Day 10

HOLY CRAP

 

Of all of the different looks ahead tacked in above today here, I like the "hour 234", 18z init., Dec. 24th valid for 12z on the 3rd [Jan.] main GFS-parallel 500mb (bottom of post 4919 above.), along together with that similar more based on Climatology (following post.), …. for "cold" plus, potential.

 

This with their showing cold having moved the furthest West—if focused somewhat north of WA as a whole—of any posted. And with what they show more as a whole, both being in line with what I've projected more generally main and broader cold air mass potential focused more recently. More essentially here, with as I see things broader cold's at that point being at a maximum "consolidation" in line with its current general regress more northward, set to culminate about then; and so with this, more primary cold at that point being set to begin moving more south again as a whole. These ideas with, importantly, otherwise (per my view, and if more general figuring.), colder air's being set—following a more extended period of more slowed movement more eastward .. having perhaps lent to the retrograde of cold depicted—only to have just begun a transition to a shorter period of more assertive movement east. Or more ESE.

[IbrChris]

I'm going to call BS on the weeklies after January 15th..forecasted pacific circulation doesn't fit the forcing progression at all. We're going back into a +PNA for the 2nd half of January..

Good thing they only go through Jan 19th then.

 

However it's not all roses for PNW on Weeks 3-4...roughly half the ensemble members have a fairly climo look with a trough just off the west coast and a nice mid-con ridge. Gone is that pesky Baffin Island/Greenland block and the pesky -NAO that means all goods just slide east most of the time. I'm being a bit facetious here.

 

I think you folks on the east coast can deal with giving us westerners a taste of winter for a week or two, after all it'll be back late January through March.

 

Alternatively the Euro Weeklies may be full of schitt....although I'd wager the CFS is almost always full of it.

[IbrChris]

Too bad, so sad. It's our turn...maybe. Perhaps?

http://www.wsi.com/blog/energy/the-case-of-the-missing-nao-block/

Also, http://www.wsi.com/blog/energy/us-the-evolution-of-the-cold-during-end-of-the-month-into-early-january/
 

And what is this sorcery?



Granted it is WSI and week 5...lolol.

Also clustering seems to be the big "new thang" in ensemble analysis...I see WSI has developed their own ensemble clustering algorithm. Not sure if the clusters are available to clients as I don't have a WSI sub anymore. I have access to clustering products through another source and I used it to analyze the various ensemble solutions on the 12z runs (posted earlier).

http://www.wsi.com/blog/uncategorized/europe-using-the-cluster-analysis/

[Front Ranger]

I'll be travelling for a couple days for work next week. I'll be in Denver on Wednesday. Looks cold.

 

I was telling Black Hole, if the Euro verified we could probably pull off a sub-zero day.

[Bryant]

I'm going to call BS on the weeklies after January 15th..forecasted pacific circulation doesn't fit the forcing progression at all. We're going back into a +PNA for the 2nd half of January..

Based off the current tropical forcings, I definitely agree our window is over once we reach the half way point of January. However, isn't it possible the pattern resets with tropical forcing once again initiating in the Indian Ocean due to a SSWE?

[Front Ranger]

Oh look 10 days out again.. Rinse repeat until March

 

The 18z actually showed a snow chance for some with that little clipper system this weekend. And all models except the GEM are showing a modified Arctic air mass entering the region within 5 days.

 

With the model runs today, a response like this is a little baffling.

[Snow]

The new 18z GFS Dec. 28 at 4pm. Per the GFS extracted data, there is 0.05" liquid precipitation for PDX when flow turns offshore which would bring sticking snow to the Valley floor. Oh how fun it would be if we can going into this cold air with snow cover.

 

http://www.tropicaltidbits.com/analysis/models/gfs/2014122418/gfs_mslp_pcpn_frzn_nwus_17.png

[richard mann]

18z GFS Ensembles 850mb temps

Before day 7 - As mentioned by far the coldest yet. Mean temps all dropped substantially over previous runs with a cluster of members below -10c. Based on this improvement over previous runs there is room for the mean temp to drop further ...

 

.. Relative, to what I've said suggested above, I've also been looking at the idea that the models, "may" just "perhaps" be underestimating the pace of cold's—looked at as a whole—movement more eastward from this point through to the first few days of January. Which would certainly tend to figure in to the actual sets up more kinetic as things move more forward.

[IbrChris]

My 2 cents: we are going to see a lot more runs depicting PNW arctic blast scenarios coming out over the next week or so.

[SilverFallsAndrew]

My 2 cents: we are going to see a lot more runs depicting PNW arctic blast scenarios coming out over the next week or so.

Score

[Snow]

The new 18z GFS Dec. 28 at 4pm. Per the GFS extracted data, there is 0.05" liquid precipitation for PDX when flow turns offshore which would bring sticking snow to the Valley floor. Oh how fun it would be if we can going into this cold air with snow cover.

 

http://www.tropicaltidbits.com/analysis/models/gfs/2014122418/gfs_mslp_pcpn_frzn_nwus_17.png

I'd also like to add it seems some moisture "breaks away" from the main L that goes to Idaho. It looks like it wants to heads S along with the initial blast of cold air. If this can make it to the Valleys that would be spectacular. We need to watch this closely on the 00z tonight.

 

http://www.tropicaltidbits.com/analysis/models/gfs/2014122418/gfs_mslp_pcpn_frzn_nwus_18.png

http://www.tropicaltidbits.com/analysis/models/gfs/2014122418/gfs_mslp_pcpn_frzn_nwus_19.png

[MikeInEverett]

The new 18z GFS Dec. 28 at 4pm. Per the GFS extracted data, there is 0.05" liquid precipitation for PDX when flow turns offshore which would bring sticking snow to the Valley floor. Oh how fun it would be if we can going into this cold air with snow cover.

 

http://www.tropicaltidbits.com/analysis/models/gfs/2014122418/gfs_mslp_pcpn_frzn_nwus_17.png

Of course nothing in Seattle