December 2016 Observations and Model Discussion for the Pacific Northwest

[Gradient Keeper]

Day 7 block much better, nice tilt...

 

http://maps1.pivotalweather.com/maps/models/gfs/2016123000/168/500h_anom.na.png

[FroYoBro]

The first week of January may be a bit cold. 

[van city]

HR 150 watching the 'kink' in pattern over southwestern BC. If it digs out further we'll see snow

 

 

http://maps1.pivotalweather.com/maps/models/gfs/2016123000/150/500h_anom.na.png

The best weather play by play. This place is not the same when you are not here.

 

Highly appreciated.

[Heavy Snow]

That low sliding south on Thursday is back, clearly stronger than on the 18z. Not sure yet where it heads.

 

Edit: Plows straight into OR/CA border.

Yeah but D**n it heads into Medford.

[TT-SEA]

Down to 33.    That was an very quick drop... 7 degrees in about 30 minutes.

[Gradient Keeper]

Day 8 back to 513/514 thickness PDX

[Heavy Snow]

Day 8 back to 513/514 thickness PDX

Awesome!

[Gradient Keeper]

Day 8-9  Oh yeah!!!

 

http://maps1.pivotalweather.com/maps/models/gfs/2016123000/180/500h_anom.na.png

[Gradient Keeper]

Wow. We might MIGHT see an extreme backdoor blast day 9-11

[TT-SEA]

FWIW... the GFS MOS has been consistent in showing a high near 40 in Seattle on Sunday.    

 

If true... then what snow falls in the lowlands on Saturday night might melt in that painful period between the moisture dropping out of the area and the actual cold air arriving.   I have seen it happen many times.   

 

The GFS MOS was correct about last Saturday when it showed a high around 40 in Seattle and I said it had to be wrong.

[SilverFallsAndrew]

29 degrees here at my house. Very puzzled by this. This is the first time this month I have not had the temp fall after sunset. I am beyond puzzled. Cloud cover is moderate compared to last night. Last night the clouds rolled in thick and heavy and I still managed to fall down to 24 for a low. WTF? Lol.... 

 

 

In other news.....today was a blast for my entire family. The 5 of us (yes I have 3 kids spent the last 4 hours of daylight sledding down a pathway partially built with the plow on the atv. I spent 2 hours yesterday plowing the berm to slide down and compacting the "runway" for them to sled down. I'll have to get a video of it and post it. Pretty surreal honestly. Its the same hill we use for the slip n slide during summer. A buddy of mine is one of those guys that puts up and takes down new billboard signs....he gave me an old billboard vinyl sheet last summer that we used as a slip n slide. Neat stuff. 

 

Probably pulling up some southerly flow ahead of the front that is sliding south tonight.

[Gradient Keeper]

Wow. We might MIGHT see an extreme backdoor blast day 9-11

Blast cut-off, for now..... Real cold run though!!

[MR.SNOWMIZER]

Next Thursday is going to be the day to watch. Looks very possible for some good development off Vancouver island. 00z hints at this.

[SilverFallsAndrew]

FWIW... the GFS MOS has been consistent in showing a high near 40 in Seattle on Sunday.    

 

If true... then what snow falls in the lowlands on Saturday night might melt in that painful period between the moisture dropping out of the area and the actual cold air arriving.   I have seen it happen many times.   

 

The GFS MOS was correct about last Saturday when it showed a high around 40 in Seattle and I said it had to be wrong.

 

I don't see this upcoming cold snap being as cold for Seattle as it will be for PDX. Could be wrong, but this feels more Dec 13' than November 2010, at least at the beginning. 

[Gradient Keeper]

The best weather play by play. This place is not the same when you are not here.

 

Highly appreciated.

Thanks, I appreciate that. Doing analysis is fun, especially when the models look better

[MossMan]

I don't see this upcoming cold snap being as cold for Seattle as it will be for PDX. Could be wrong, but this feels more Dec 13' than November 2010, at least at the beginning.

Yay Oregon scores again!

[MR.SNOWMIZER]

FWIW... the GFS MOS has been consistent in showing a high near 40 in Seattle on Sunday. Of course outline areas may only be around 34 35 also.

 

If true... then what snow falls in the lowlands on Saturday night might melt in that painful period between the moisture dropping out of the area and the actual cold air arriving. I have seen it happen many times.

 

The GFS MOS was correct about last Saturday when it showed a high around 40 in Seattle and I said it had to be wrong.

[Gradient Keeper]

00z quite a bit colder and through next Saturday now

[TT-SEA]

I don't see this upcoming cold snap being as cold for Seattle as it will be for PDX. Could be wrong, but this feels more Dec 13' than November 2010, at least at the beginning. 

 

 

Well... the WRF does not show much snow for the Seattle area on Saturday night anyways... its all focused out here in the foothills.

 

It does appear that it will take awhile for the cold air to bleed in and Sunday will be frustratingly mild for the lowlands anyways.    

 

Maybe there will be some unexpected precip with the arrival of the actual arctic air later on Sunday night.  

[crf450ish]

The first week of January may be a bit cold. 

My wife and I will be ringing in new years in our arctic parkas and bunny boots watching our neighbors light off about a grand in fireworks. Should be good times. Our kids will be asleep as they always are at that hour

[SilverFallsAndrew]

Yay Oregon scores again!

 

Well Arlington is going to get some great radiational cooling like always...

[Heavy Snow]

Blast cut-off, for now..... Real cold run though!!

Yeah looks awesome but I'm concerned it's too dry.

[Goducks09]

I'm beginning to think we see some ice-chunking on the Columbia.  Cue the live shots from a frozen Multnomah Falls!

[TT-SEA]

Snow through Sunday morning per the 00Z WRF... same theme as the last few runs.

 

http://www.atmos.washington.edu/wrfrt/data/current_gfs/images_d2/wa_snow48.60.0000.gif

 

 

 

Precip on Sunday morning is mostly south of the area as well...

 

http://www.atmos.washington.edu/wrfrt/data/current_gfs/images_d2/pcp1.60.0000.gif

[Goducks09]

Reload incoming at 234!  Geez...

[SilverFallsAndrew]

Well... the WRF does not show much snow for the Seattle area on Saturday night anyways... its all focused out here in the foothills.

 

It does appear that it will take awhile for the cold air to bleed in and Sunday will be frustratingly mild for the lowlands anyways.    

 

Maybe there will be some unexpected precip with the arrival of the actual arctic air later on Sunday night.  

 

Seems like the first day always does that.

[SilverFallsAndrew]

The 504 500mb heights entering N British Columbia are impressive...

 

http://www.tropicaltidbits.com/analysis/models/gfs/2016123000/gfs_z500a_namer_40.png

[MR.SNOWMIZER]

Precip with a true arctic push coming down the sound is impossible for the models to pinpoint. We wont know before it begins to happen.

[Poulsbo Snowman]

.LONG TERM...It is Saturday afternoon and evening where the
  headaches begin. ECMWF and GFS fall out of lockstep for Saturday and
  Sunday...which given the incoming colder air and the precip
  associated with the incoming system...results in a fair number of
  possibilities for the New Years Eve/Day timeframe. ECMWF is more
  progressive and colder with the system...but overall less precip
  while the GFS has more precip...is slower and slightly less cold.
  Given trends in both models...currently more inclined to lean toward
  the GFS solution...which would start the event as rain on New Years
  Eve then changing over to snow during the early morning of New Years
  Day. This sort of timing actually takes the edge off of the greater
  precip amounts of the GFS...placing the bulk of precip more during
  the rain phase...but should rain end up being too much too
  fast...that could actually help the chances for transition to snow
  earlier. If that sounds like hedging or indecisiveness...welcome to
  the fun of trying to forecast snow.  As touched on briefly before
  laying out the scenarios...inclined to lean toward GFS due to its
  more consistent progs. But even with GFS`s own difficulty in guiding
  in regards to transition times...as it seems to be an hour or two
  off using the previous instance as a mental milepost...inclined to
  side with later timings. Definitely too early to suggest
  amounts...but current thinking is to pare back a little bit on
  inherited forecast...bringing lowland snow amounts more in the 1 to
  1.5 inch range. 
  
  Behind all of that hullabaloo...models re-align for cold and dry
  conditions over W WA...with sub-freezing afternoon highs for the
  first half of next week.  SMR 
  
 

[crf450ish]

Probably pulling up some southerly flow ahead of the front that is sliding south tonight.

Sounds about right. As soon as I read your reply I jumped up and went outside and sure enough, theres a very slight breeze coming from the south. No worries. I am looking forward to cool dry weather for a few days going into new years. I get a reprieve from the incessant plowing I have had to do the last two weeks. Not to mention a halt to the friggin ice dams building up on parts of my metal roof.

[TT-SEA]

Precip with a true arctic push coming down the sound is impossible for the models to pinpoint. We wont know before it begins to happen.

 

 

The 00Z GFS hints at precip around the Seattle area on Sunday night into Monday morning.   That is the best time to get some snow that will actually last through the cold spell.  

[SilverFallsAndrew]

Canadian handles the "re-load" in a very snowy fashion. From PDX to EUG the snow level may lift off the valley floor at times, but at face value looks good. 

[Poulsbo Snowman]

Don't know how that happened.  Here's what I wanted:

 

Special Weather Statement
National Weather Service Seattle WA
722 PM PST Thu Dec 29 2016

WAZ001-503-504-506-507-509>511-514-555-556-558-559-301730-
San Juan County-Western Whatcom County-Southwest Interior-
Western Skagit County-Everett and Vicinity-Tacoma Area-
Admiralty Inlet Area-Hood Canal Area-
Eastern Strait of Juan de Fuca-East Puget Sound Lowlands-
Bellevue and Vicinity-Seattle and Vicinity-Bremerton and Vicinity-
722 PM PST Thu Dec 29 2016

...Lowland snow likely over parts of interior western Washington
this weekend...

There is a high likelihood that at least some of the western
Washington interior will get accumulating snow sometime between
late Saturday afternoon and New Years Day.

Confidence is fairly high about the large-scale weather setup,
which shows cold Canadian air spreading south on Saturday night,
nipping at the heels of exiting showers later Saturday night and
on Sunday morning. So the main forecast issues to resolve will be
knowing where showers will focus and be heaviest, when a
transition from rain to snow will occur, and how soon showers exit
the area.

Depending on these timing and coverage details, it appears most
of the interior lowlands will get a Trace to 3 inches of snow.

From the Seattle area on north to the Canadian border, there is a
high likelihood of many places exceeding one inch of snow. The
most likely time for snow near Bellingham is early Saturday
evening, then later evening further south in the Seattle area.

From the Bremerton and Tacoma areas on south, one-inch
accumulations will be much less common. Any snow that does occur
is most likely from late Saturday evening into Sunday morning.

Even a little bit of snow with falling temperatures can cause
roads to become slick and hazardous. Please plan ahead and check
back for the latest forecasts, especially if you have plans to be
out later on New Years Eve.

Beyond Saturday night, temperatures will get quite a bit colder.
Starting Sunday night, hard freezes are expected each night into
the latter half of next week, and afternoon highs will only reach
the upper 20s to mid 30s. With such cold temperatures, any snow
or ice on untreated surfaces is likely to stick around well into
next week.

$$

 

[Heavy Snow]

[HighlandExperience]

Well... the WRF does not show much snow for the Seattle area on Saturday night anyways... its all focused out here in the foothills.

 

It does appear that it will take awhile for the cold air to bleed in and Sunday will be frustratingly mild for the lowlands anyways.

 

Maybe there will be some unexpected precip with the arrival of the actual arctic air later on Sunday night.

Sadly you might be right. Just seems most of these arctic fronts have been pretty weak and slow recently.

 

They just slowly bleed in, and we get nothing below 700 feet or so.

[EA_TTD]

Yeah looks awesome but I'm concerned it's too dry.

Maybe change your name to "Face Freezing East Wind"?  That should help.

[MR.SNOWMIZER]

There are usually better anow ratios with a arctic front also so dont take as much moisture to lay down a few inches.

[crf450ish]

I'm beginning to think we see some ice-chunking on the Columbia.  Cue the live shots from a frozen Multnomah Falls!

Hell yeah! Last time the confluence of the Spokane and Columbia froze over was in 1996....if it happens again, I am renting a wet suit and going swimming with my GoPro. No ifs ands or buts about it. Period. Once in a lifetime event.......or will it be?

[FroYoBro]

Finally moisture comes but it's rain for me.

 

 

Hour 264. 

[SilverFallsAndrew]

Clown range GFS is a major letdown.