December 2020 Weather Observations for the PNW

[bainbridgekid]

Interesting little feature on the 18z 10 days out.

 

[SilverFallsAndrew]

13 minutes ago, bainbridgekid said:

Interesting little feature on the 18z 10 days out.

 

Most recent GFS runs have actually had a decent trough in that period. 

[AbbyJr]

[snow_wizard]

13 minutes ago, AbbyJr said:

Getting some consistency with that model.

[snow_wizard]

32 minutes ago, bainbridgekid said:

Interesting little feature on the 18z 10 days out.

 

Nice baroclinicity on that one.  It wouldn't be shocking to see that happen after what we saw a few days ago.

[SilverFallsAndrew]

13 minutes ago, snow_wizard said:

Nice baroclinicity on that one.  It wouldn't be shocking to see that happen after what we saw a few days ago.

The track of that system with cold air feeding in behind it is a pretty classic setup for a wet 3-5" snow event here. Models have been teasing something in that range, so we will see. 

[TheNewCulverJosh]

18 minutes ago, snow_wizard said:

Nice baroclinicity on that one.  It wouldn't be shocking to see that happen after what we saw a few days ago.

The odds on that exact feature happening 10 days out is between 3 and 5 percent, according Mr. Mark Nelsen.

[Gradient Keeper]

00z GFS Day 1

[Gradient Keeper]

Day 2

[Gradient Keeper]

Day 3

(Past 4 runs)

[Gradient Keeper]

Day 4

(Past 4 runs)

[AbbyJr]

1 hour ago, snow_wizard said:

Getting some consistency with that model.

And this is the mean too.

[Gradient Keeper]

Day 5 (North Pacific view)

(Past 4 runs)

[Gradient Keeper]

Day 6

(Past 4 runs)

[Jesse]

50/38 spread today. Morning rain then afternoon scattered showers and sunbreaks.

[Gradient Keeper]

Day 7 (North America view)

(Past 4 runs)

[Gradient Keeper]

Day 8 (North American view)

(North Pacific view)

[Gradient Keeper]

Big changes over NE Canada with less blocking. Hmmm....

[Gradient Keeper]

Day 9'er (North America view)

(North Pacific view)

[Phil]

1 hour ago, AbbyJr said:

That’s more like it!

[Gradient Keeper]

Day 9-10 Puget Sound snow

[Gradient Keeper]

00z GFS 10 Day Rainfall, Snowfall totals

[SilverFallsAndrew]

Loving this run. 

[Gradient Keeper]

Day 11 (Past 4 runs) WPAC jet extension considerably further west.

[Brian_in_Leavenworth]

Here is the new GFS, V16.  Running slightly behind the regular GFS.

[Gradient Keeper]

8 minutes ago, Brian_in_Leavenworth said:

Here is the new GFS, V16.  Running slightly behind the regular GFS.

Definite potential there. I do sense models are starting to reflect on the SSWE after Day 8-9 roughly. Maybe. *Shrugs

[Cloud]

Ok. Not a bad run for the GFS, let see what the Euro has to say. 

[The Swamp]

22 minutes ago, DJ Droppin said:

Definite potential there. I do sense models are starting to reflect on the SSWE after Day 8-9 roughly. Maybe. *Shrugs

yeah but that just looks like a good mountain snow pattern and 42 degree rain for the lowlands.........ZZZZZzzzzzz

 

[Omegaraptor]

45 minutes ago, DJ Droppin said:

Day 9-10 Puget Sound snow

Should be fun for anyone driving over the Sierra.

[Cloud]

Was barely able to not get to 50 today. Tomorrow is gonna be another close one and if we can get past it, the rest of the month should be good to end the year. Seen enough 50s and 60s for this month already. 

[MossMan]

Currently 41 degrees.

.17” so far on the day. 

[Gradient Keeper]

It's only 22 in Pasco and 29 at The Dalles. I'm surprised by that. PDX-DLS now offshore

[Deweydog]

46 minutes ago, SilverFallsAndrew said:

Loving this run. 

We got the Andrew back!

[Gradient Keeper]

Just now, Deweydog said:

We got the Andrew back!

All is right again with the world, or at least with the Forum.

00z ECMWF in 9 minutes

[SouthHillFrosty]

Staying in a cabin tomorrow night with the gf in the Leavenworth area. How much snow do you guys have over their rn? @Brian_in_Leavenworth

[Gradient Keeper]

00z ECMWF Day 1 

[Brian_in_Leavenworth]

Just now, SouthHillFrosty said:

Staying in a cabin tomorrow night with the gf in the Leavenworth area. How much snow do you guys have over their rn? @Brian_in_Leavenworth

6 inches in the city.  We had about one inch of ice (snow from last week, then it got rained on, and what was left over was a solid sheet of ice), then got about 5 or 6 inches Christmas evening.  It will last.  Next snow around Wednesday.  If your cabin is toward Lake Wenatchee/Plain, you will no doubt have more.

[SouthHillFrosty]

 

Wow

[Gradient Keeper]

Day 2

[Deweydog]

4 hours ago, paulb/eugene said:

000 
TTAA00 KSEA 290957
LTL CHG IN BASIC PATRN OF STG W-E JET ALG 55N...HI HGTS OVR WA AND LTL
IF ANY PVA OR SIGNFNT S/WVS MVG THRU STATE. BAD STLT PICS POORLY SHW
BACLIN BAND ACRS VRISL MVG SLWLY SWD IN RSPNS TO CD UPR LO IN SRN AK
SO HIGHEST POPS AT UIL AND BLI. BACLIN BAND LIKELY TO STALL JUST N OF
WA. BIG QUESTION AFT 48 HRS IS HOW FAR S WILL CD UPR AK LO DROP. WILL
IT CONT TO DROP STRGT SWD TWD WA OR WILL IT STRT RTRGRTNG W BOUND AND
END UP UNDER BERING SEA BLK. THIS PUTS WA IN CONTD RDGG WITH ANTICYC
FLO. NEW RUN OF MRF SHLD SHED SM LIGHT ON THIS. ERN WA STUCK IN THE
SOUP HWVR BOTH NGM AND MRF INCRS THE SLY GRAD ACRS ERN WA ON MON SO
SE AND XTRM E PRTS COULD TMPRLY BRKOUT WITH MAX TMPS MVG UP SM. FOG
AND ST TDA WILL HOLD DWN MAX TMPS BLO WHAT MOS SAYS. INTERESTING TO
NOTE THAT BOTH NGM AND LFM DVLP 1072 MB ARCTIC HI IN ERN AK IN 48
HRS WHICH WOULD SHATTER THE PRVS N AMRCN RCRD HI PRES OF 1067.6 MB
SET ON JAN 1 1974 IN THE YUKON TERR. NEW 06Z MRF RUN JUST CAME IN
AND NEW 120 HR VALID 00Z FRI WILL KNOCK YOUR SOCKS OFF COMPARED TO PRVS
RDGG PATRN. REFUSE TO JUMP ON THIS UNTIL 2ND MRF RUN TNGT CONFIRMS
OR ELSE YO YOS BACK TO RDGG. MRF TYPICALLY POOR WITH BLKS SPLTS
AND NRN FLO S/WVS COMNG DWN FM AK. HWVR =IF CORRECT HANG ONTO YOUR
SOCKS. BC

It’s interesting they talked about the upper low retrograding under the block, which is something that has always fascinated me about the 1989 blast. Intense cold air masses with so much overwater trajectory almost always have a tendency to do that as they become cyclogenic.  December 1992 and January 2005 are pretty good examples.

That thing just overwhelmed the norms.  Cold onshore flow with temps in the mid 20’s is pretty incomprehensible.

Also shows how dependent we’ve become on long term leads.  I specifically remember there was no SWS or mention of any potential until Monday morning by NWS Astoria.  Arctic air arrived Wednesday morning.