December 2016 Observations and Model Discussion for the Pacific Northwest

[Gradient Keeper]

Still seeing that Kona Low. No idea what the NWS/NCEP forecaster is seeing to forecast it dissipates. I wish he were correct.

 

Need that upper level trough off Siberia to back off too. Not going to happen.

[Gradient Keeper]

What are your thoughts as far as snowfall in PDX on Monday?

Below 500', mix/wet snow slushy accumulations possible. Too much southerly flow aloft on soundings. The only way we could overpower the southerlies I guess is if we had good precip rates and strong CAAdvection

[Gradient Keeper]

Here is a significant change from previous runs. In fact, no other runs have showed this yet. Day 6 very deep 975mb low offshore.

 

http://www.tropicaltidbits.com/analysis/models/gfs/2016120306/gfs_mslp_pcpn_frzn_nwus_24.png

 

 

 

 

HR 150 970mb northern Vancouver Island

 

http://www.tropicaltidbits.com/analysis/models/gfs/2016120306/gfs_mslp_pcpn_frzn_nwus_25.png

[Gradient Keeper]

GFS is flat out clueless after day 4

 

Most consistent model the past 3 days has actually been the GEM.

[Gradient Keeper]

At 6z NWS initialized the Kona Low at 1014mb. I can see the circulation on IR Loop also. Let's hope it develops very slowly. You can also see the building Aleutian ridge which becomes the GOA/Alaskan block, and as well the flat offshore ridge. However, as of 1 AM still do not see any pressure falls north of Hawaii.

 

http://i.imgur.com/D8Nc95u.gif

[OKwx2k4]

At 6z NWS initialized the Kona Low at 1014mb. I can see the circulation on IR Loop also. Let's hope it develops very slowly. You can also see the building Aleutian ridge which becomes the GOA/Alaskan block, and as well the flat offshore ridge. However, as of 1 AM still do not see any pressure falls north of Hawaii.

 

http://i.imgur.com/D8Nc95u.gif

So, I have a dumb question. Why is a Kona Low a bad thing?

[Gradient Keeper]

So, I have a dumb question. Why is a Kona Low a bad thing?

Not a dumb question at all. It's fine if it remains well south near Hawaii, but models show it eventually develops moving northeastward. In this case it's bad because it shoves the ridge east(along with a trough departing off Siberia) and worst of all the flat ridge off the OR/CA coast does not suppress as much as it could which also doesn't allow the arctic trough to continue to dig south-southwest offshore down the coast.

[Gradient Keeper]

Hmmm,

 

Interesting tidbit from the Anchorage NWS "The air mass is colder
and denser in reality than the models have represented."

I wonder if there might be a bit more punch to the arctic trough than models are showing and thus it might dig more southward than we are currently seeing.

 

Also, several 00z EPS members deliver arctic air over us after day 9.

[Gradient Keeper]

This is interesting. The Canadian Ensemble 6-10 day Composite Analog is much improved. Look even 2008 popped up. The positive anomaly/block position is pretty good and cross polar flow too. Granted the correlation score skill level is low, but this sort of seems to follow the colder/snowier operational run we've seen the past few days.

 

http://www.cpc.ncep.noaa.gov/products/predictions/short_range/tools/gifs/500hght_comp_can610.gif

[Gradient Keeper]

6z after day 7 continues to show an incredibly deep and arctic cold pool persisting over the Columbia Basin. Excellent to tap into if the pattern upstream becomes favorable.

[Gradient Keeper]

[ Model Countdown ]

Next up....

*12z GFS in 4 hours

12z GEM in 5 hours

12z ECMWF in 6 hours 17 minutes

I think I'll be here for 12z runs.... root for COLD!!!!

[MossMan]

 

[ Model Countdown ]

 

Next up....

 

*12z GFS in 4 hours

 

12z GEM in 5 hours

 

12z ECMWF in 6 hours 17 minutes

 

I think I'll be here for 12z runs.... root for COLD!!!!

Get some rest and thanks for all your awesome info and model reading!!

[Gradient Keeper]

Get some rest and thanks for all your awesome info and model reading!!

You're welcome. I can't rest.... Doing analysis or things to keep my mind preoccupied is the only thing helping.

[westcoastexpat]

GFS, ECMWF, GDPS all speaking different languages. Definitely a complicated pattern this month.

[Timmy]

Interesting to note, the hires wrf (1 1/3km) still shows snow accumulation over pdx. And about 2" at the airport. Gives me 4-5"

[Randyc321]

On another note, the 00z GEM sure is nice. 6-10 inches for most of Western WA by Friday afternoon. Lock it in. It's happening. Done deal.

 

In the believable range, it shows 2-3 inches by Tuesday morning for most places away from the water.

That shows like 9-10 inches for my part of the island.  I don't even know if we have snow plows on Bainbridge very often.  I haven't lived here since before the snow stopped falling in Western Washington.  I don't mind being stuck at home!  

 

I would love for this to prove out.

[Timmy]

12z brings a swath of moisture through Nw oregon Tuesday morning and gives me a 36 hour total of 8"+

[Timmy]

And gives pdx over 6"

[Timmy]

Deformation band

[FroYoBro]

And give pdx over 6"

Weird. That has been my exact forecast for Portland. Definitely looking at a 6 inch snowstorm. 

[Timmy]

Weird that has been my exact forecast for Portland. Definitely looking at a 6 inch snowstorm.

Haha, right...

[chopper 918]

Yep, most will wake up to 6 inches at their backdoor.

[FroYoBro]

The 12z definitely looks good for snow Tuesday morning as the low dies southward right near the Portland area. It actually looks to show fairly heavy rates. 

[crf450ish]

You're welcome. I can't rest.... Doing analysis or things to keep my mind preoccupied is the only thing helping.

Sleep deprivation can be taxing on the brain. 

[Farmboy]

Hmmm,

 

Interesting tidbit from the Anchorage NWS "The air mass is colder

and denser in reality than the models have represented."

 

I wonder if there might be a bit more punch to the arctic trough than models are showing and thus it might dig more southward than we are currently seeing.

 

Also, several 00z EPS members deliver arctic air over us after day 9.

Well, The Weather Channel isn't completely sold on that idea, they've actually raised their forecast high for wednesday for areas in western Washington and raised tuesday night's lows....  What a bunch of backwards-thinking buffoons.

[Timmy]

Well, The Weather Channel isn't completely sold on that idea, they've actually raised their forecast high for wednesday for areas in western Washington and raised tuesday night's lows.... What a bunch of backwards-thinking buffoons.

What's the weather channel?

[ShawniganLake]

Well, The Weather Channel isn't completely sold on that idea, they've actually raised their forecast high for wednesday for areas in western Washington and raised tuesday night's lows....  What a bunch of backwards-thinking buffoons.

Those forecasts are probably computer generated.  Nobody is thinking and making a forecast for 100's of thousands of cities around the world. 

[Brennan]

I'm liking what the 12z GFS is trying to do midrange. Building heights over the Pacific again and a low coming straight at us... Looks progressive though. As soon as heights build they get smashed east.

[crf450ish]

WU keeps increasing the snowfall amounts for me next Thursday. Was 3-5", now 5-8"....maybe it'll be a foot by the time it arrives. 

 

http://i.imgur.com/y4qBDCV.png

 

Looks like I'll definitely be using the ATV snow plow. I'll be sure to post pics and maybe a short video. Its the most wonderful time of the year. 

[SilverFallsAndrew]

http://www.cascadeaccess.com/~mnelsen/RPM_72_SNOW_12z.jpg

[Brennan]

I could live with the GFS toying with this scenario... drop that low a tad south. we have plenty of cold air to draw from NE. 

[SilverFallsAndrew]

http://www.tropicaltidbits.com/analysis/models/gem/2016120312/gem_mslp_pcpn_frzn_nwus_19.png

[Phil]

GFS is dangling some red meat in the clown range. Much less amplified EAMT/Branstrator Wave.

[Heavy Snow]

If anybody wants to experience a Blizzard head to the Gorge next week. The updated run of the 00z KING EURO OP shows Cascade Locks getting 38 inches of snow over the next 10 days. The ensemble mean was even higher at 56"!

[Phil]

GFS is dangling some red meat in the clown range. Much less amplified EAMT/Branstrator Wave.

Also has the tropical forcing/poleward WAFs further east, closer to 140E/150E instead of 120E. If this comes to fruition, it bodes much better for you guys.

[Sometimesdylan]

Hmmm,

 

Interesting tidbit from the Anchorage NWS "The air mass is colder

and denser in reality than the models have represented."

 

I wonder if there might be a bit more punch to the arctic trough than models are showing and thus it might dig more southward than we are currently seeing.

 

Also, several 00z EPS members deliver arctic air over us after day 9.

 

Juneau NWS:

"Low level warm air advection associated with yesterday's storm has

finally run out. High temperatures today will occur early in the

day and then begin a steady fall through the afternoon and over

night."

 

About 37 degrees this morning. Will be the last high above 30 I feel for a while. With events like this, it's cool knowing that I'm upstream of you guys.

 

Gonna feel some arctic air tomorrow! For now I'm just hoping this heavy rain turns to snow before things clear out. The NWS here mentioned a convergence zone somewhere near Juneau a couple discussions ago. Would be awesome if that happened.

[chopper 918]

http://www.cascadeaccess.com/~mnelsen/RPM_72_SNOW_12z.jpg

Mark Nelsen uses and trusts his RPM model very highly, so maybe we will see a little something

[SilverFallsAndrew]

UW WRF is very generous for my location...

[Timmy]

Mark Nelsen uses and trusts his RPM model very highly, so maybe we will see a little something

The last couple winters the wrf has been king at least in lower elevations near me.

[Kayla]

12z GFS definitely shows a nice little snowstorm for PDX on Tuesday now. 6" of snowfall being shown to fall on Tuesday now after 1-2" falls on Monday. 925s are -3c on Tuesday so plenty cold enough to support sticking snow.

 

Trend has definitely been on Portlands side these last 48 hours!