December Weather In the PNW

[Geos]

3km NAM actually shows more snowfall across a wider area of Puget Sound than the 18z while maintaining a slight emphasis on King and Snohomish counties... More similar to the 12z run.

 

Looks good to me.

 

Was just noticing this model is running way warm on the temps now. Like 4-5 degrees.

Temp is tanked really rapidly tonight. Already approaching the morning low of 24 here. 

[Winterdog]

I have a bad feeling about the Euro. Hope my feeling is wrong.

Yeah, me too.

[HighlandExperience]

[MR.SNOWMIZER]

-5 at my cabin property. By friend lives close and temps there match mine at cabin.

[SilverFallsAndrew]

Totally shooting from the hip here, but I think our next opportunity comes in the January 15-25 range. 

[seattleweatherguy]

You can see it yourself by going to https://www.tropicaltidbits.com/analysis/models/?model=nam3km&region=nwus&pkg=asnow&runtime=2017122400&fh=0&xpos=0&ypos=0

Thanks for the link. Got to start book marking these and learn how to zoom in

[jaya]

What is interesting in the 00z GFS is how the jet keeps pushing energy into Astoria.  May not be too bad in portions of W WA if the systems are stronger and keep pulling cool air down from Canada.

[jaya]

Was just noticing this model is running way warm on the temps now. Like 4-5 degrees.

Temp is tanked really rapidly tonight. Already approaching the morning low of 24 here. 

Unfortunately, the temperatures are near ground.  Shallow cold air from nocturnal cooling can be eroded very quickly.

[SilverFallsAndrew]

The extended GFS keeps hinting at some cold troughing... We'll see...

[TT-SEA]

Of course I know that. But I like seeing the wxbell images. They just do a good job with the way their graphics present. It’s pretty like an Apple product

 

Total snow through 4 p.m. Monday.

 

I find the GFS snowfall maps to be fairly inaccurate though.

 

[umadbro]

I have a feeling a lot of meteorologist are going to be writing about how the EURO is the superior model and America needs to figure out how to catch up to it... Again...

[TT-SEA]

In one hour... by around 10:05 we will have 00Z ECMWF surface maps through 48 hours.

[jaya]

I have a feeling a lot of meteorologist are going to be writing about how the EURO is the superior model and America needs to figure out how to catch up to it... Again...

No one model is better in every situation. But the ECMWF does do a much more thorough initialization (they spend hours just initializing their model) then run it at higher resolution.  US runs faster, more often, and they run many more models.  EC has more horsepower as well.  I guess the reason we are chasing them are due to the questions: "how good is good enough?" and  "how much are you willing to spend?"  How much spending do you want on weather forecasting vs other things that the gov needs to pay for?  Above my pay grade.

[luvssnow_spokane]

In one hour... by around 10:05 we will have 00Z ECMWF surface maps through 48 hours.

Going to be a reality check

[MR.SNOWMIZER]

What is interesting in the 00z GFS is how the jet keeps pushing energy into Astoria.  May not be too bad in portions of W WA if the systems are stronger and keep pulling cool air down from Canada.

I was looking at that as well. It's not far off from being a fun time with snow chances.

[Jesse]

I have a feeling a lot of meteorologist are going to be writing about how the EURO is the superior model and America needs to figure out how to catch up to it... Again...

And they will be right.

[GHweatherChris]

The best model will be the GOLU for this, my gut says more snow will fall than what is shown in the real models. But that's just me....

[Farmboy]

Unfortunately, the temperatures are near ground.  Shallow cold air from nocturnal cooling can be eroded very quickly.

Buzzkill post of the night...

[HighlandExperience]

And they will be right.

If Bernie was elected we wouldn’t be having this discussion

[Poulsbo Snowman]

http://www.willigetawhitechristmas.com/This must be the equivalent to the magic 8 ball:
 

[MossMan]

What is interesting in the 00z GFS is how the jet keeps pushing energy into Astoria. May not be too bad in portions of W WA if the systems are stronger and keep pulling cool air down from Canada.

November 1996 was when I learned that Lows coming in around that area is a very good thing for us up here! Nearly 8” snow that day when the forecasts called for a quick slushy inch then a warm up by mid morning, never did change over up here.

[Jbolin]

November 1996 was when I learned that Lows coming in around that area is a very good thing for us up here! Nearly 8” snow that day when the forecasts called for a quick slushy inch then a warm up by mid morning, never did change over up here.

Wow, great memory on that event

[SilverFallsAndrew]

Buzzkill post of the night...

 

Jaya is right. I have seen it all my life. 

[MossMan]

Wow, great memory on that event

From that day forward I would watch a lot of satellite loops in hopes that we could get lows to come in around Astoria whenever there was cold air just on the other side of the border!

[luvssnow_spokane]

Jaya is right. I have seen it all my life.

 

Ditto...

[SilverFallsAndrew]

Unfortunately for PDX area folks the NWS curse has now been activated.

[MR.SNOWMIZER]

When the going gets tough i lean toward the good ol AVN model.

[Tenochtitlan]

Jaya is right. I have seen it all my life. 

Yeah, in a way it's better to have someone on this forum be the buzzkill in advance of nature itself being the buzzkill.

[HighlandExperience]

[MossMan]

[luvssnow_spokane]

Portland issuing winter weather advisory

Freezing rain

[Timmy]

[Blizzard777]

http://www.willigetawhitechristmas.com/This must be the equivalent to the magic 8 ball:

 

I got a happy snowman

[Jbolin]

Portland issuing winter weather advisory

K.O.D 

[seattleweatherguy]

Nws latest forecast discussion doesn't look as bad

[seattleweatherguy]

Current Version Previous Version: 1 2 3 4 5

AREA FORECAST DISCUSSION

 

FXUS66 KSEW 240447

AFDSEW

 

Area Forecast Discussion

National Weather Service Seattle WA

845 PM PST Sat Dec 23 2017

 

.SYNOPSIS...A weak low pressure system will pass across Western

Washington on Sunday night and Christmas morning bringing a chance

of rain and snow to the area. Weak upper ridging around Tuesday

should bring a drier period. A warmer and wetter pattern should be

in place around next Thursday and Friday.

 

&&

 

.SHORT TERM...Clear skies over Western Washington this evening

looks to be resulting in no shortage of sub-freezing temperatures

across the area. Cold though it may be...at least it is a quiet

night.

 

The same cannot be said for the upcoming holiday as the next weather

system of interest starts to seep into the area from the SW Sunday

morning. Initially there looks to be a bit of warming...but the

northward extent of this will be pretty limited...optimistically

making it to the Seattle metro area. The incoming cold front is

pretty quick to nix this however...with colder conditions kicking in

first in the Hood Canal area by mid-afternoon. For most

places...precip starting in the morning and early afternoon with

generally fall as rain...although as just stated Hood Canal is

likely to make the transition to the white stuff first. As the cold

front draws nearer mid to late afternoon...will see snow levels

north of Seattle fall quickly and a transition to snow during the

evening. For Seattle...points south and along the coast...precip

still expected to fall as rain...or perhaps a rain/snow mix...into

Sunday evening and Sunday night. The Seattle metro will likely see a

transition to snow during the overnight into early Christmas

morning. The timing of this transition will be key in determining

the amount of snowfall expected. Current forecast suggests that for

points north of the Seattle metro area...amounts of 1-3 inches are

expected when this is all said and done while the metro area itself

may see up to 2 inches with the higher end of that spectrum expected

in northern portions of the metro area. Given the amounts

possible...currently weighing the prospects of putting out a Winter

Weather Advisory for snow in a late evening update...though would

like to see the 00Z ECMWF first.

 

To avoid tunnel vision here...also worth mentioning that the

southern and central Cascades zones look to creep across their

Winter Weather Advisory for Snow thresholds as well with this

system...so weighing adding that to a potential update as well.

 

Precip will gradually taper off on Christmas Day, with just a few

lingering rain/snow showers and little additional accumulation.

 

An upper ridge will stand up near 130W on Monday night, then

flatten as the ridge axis moves inside 130W on Tue. This will

support a mostly precip-free period for the Tue/Tue night time

frame. The 12z ECMWF appears to be an outlier in showing light

precip (rain/snow mix) on Tue night. SMR/Haner

 

.LONG TERM...From Previous Discussion...Models are leaning toward a

flat ridgy solution for next Thursday and Friday, though they are

different in showing where the ridge axis will be. What the GFS and

ECMWF agree on is depicting this as a flat, dirty ridge, with rain

spreading into Western Washington next Thu night and/or Friday. Have

increased PoP for this period. The New Years weekend forecast for

now features near normal temperatures and chance PoPs. Should be

mild enough on New Years weekend to avoid lowland snow being part of

the conversation. Haner

 

&&

 

.AVIATION...Northwest flow aloft over Western Washington this

evening will back to west on Sunday as a frontal system moves into

the offshore waters. Northerly offshore flow will continue at low

levels. The air mass will remain dry tonight, with moisture

increasing Sunday -- first aloft and then at the lower levels.

 

There will be no significant cloud cover below 12,000 feet

tonight, but patchy FG/FZFG is likely in the most fog-prone spots.

Ceilings will gradually lower on Sunday, with widespread

MVFR/local IFR conditions likely late Sunday afternoon due to

reduced visibility, low ceilings, and rain/snow.

 

KSEA...Northeast wind 6-10 kt. Cloud cover will gradually lower

Sunday, with conditions probably deteriorating to MVFR late Sunday

afternoon. Light precipitation will probably begin during the

afternoon, with up to 2 inches of snow possible at KSEA by early

Monday morning. McDonnal

 

&&

 

.MARINE...High pressure over southern British Columbia will

maintain moderately strong northerly offshore flow and Fraser

outflow winds through tonight; small craft advisory winds will

continue over the northern inland waters, central and western

Strait of Juan de Fuca, and the coastal waters. Another frontal

system will move through the area Sunday and Sunday night, and the

resulting will be continuing small craft advisory winds especially

for the coastal waters. Northwest flow will follow the front for a

brief period late Sunday night and Monday, then weak offshore

flow will prevail Monday night through Wednesday. McDonnal

 

&&

 

.HYDROLOGY...River flooding is unlikely for the next 7 days. A

period of heavier rain is possible around next Thursday night or

Friday. This will bear watching for the flood-prone Skokomish

River. Other rivers may experience rises but are not expected to

flood.

 

&&

 

.SEW WATCHES/WARNINGS/ADVISORIES...

WA...None.

PZ...Small Craft Advisory until 4 AM PST Monday for Coastal Waters

From Cape Flattery To James Island 10 To 60 Nm-Coastal

Waters From James Island To Point Grenville 10 To 60 Nm-

Coastal Waters From Point Grenville To Cape Shoalwater 10

To 60 Nm.

 

Small Craft Advisory until 10 PM PST Sunday for Coastal Waters

From Cape Flattery To James Island Out 10 Nm-Coastal Waters

From James Island To Point Grenville Out 10 Nm-Coastal

Waters From Point Grenville To Cape Shoalwater Out 10 Nm.

 

Small Craft Advisory until 10 AM PST Sunday for Northern Inland

Waters Including The San Juan Islands.

 

Small Craft Advisory until 3 PM PST Sunday for Central U.S.

Waters Strait Of Juan De Fuca-West Entrance U.S. Waters

Strait Of Juan De Fuca.

 

&&

 

 

 

 

www.weather.gov/seattle

[TT-SEA]

And that map is really stupid. Have we ever seen precip coverage that looks like that? I will say it again, FUKK the models!

 

 

Actually... the 00Z ECMWF is just as phallic as the MM5 NAM at 10 a.m. tomorrow. 

 

[MikeInEverett]

Come on Euro show us the goods!

[Perturbed Member]

Think Euro is going north. Astoria landfall?

[TT-SEA]

00Z ECMWF shifted back north again... this is snow total through 4 a.m. Christmas morning.

 

http://models.weatherbell.com/ecmwf/2017122400/washington/ecmwf_tsnow_washington_7.png