PNW December 2022 - Part II

[SouthHillFrosty]

2 minutes ago, Kolk1604 said:

Looks like it's on the Pierce/King line I'll take it!

I don't have elevation support so i'm going to need temps to be on point.

This isn’t a elevation event. This is heavy snow possibly 

[Parrot]

16 minutes ago, Kolk1604 said:

My word

[SouthHillFrosty]

Not only that, we have a possibly overrunning event into Christmas Eve.

[Kolk1604]

5 minutes ago, SouthHillFrosty said:

This isn’t a elevation event. This is heavy snow possibly 

Just concerned about temps that's all. 

It does get good by Friday though 

[Requiem]

GFS is frigid. Pretty incredible low level blast

[SouthHillFrosty]

2 minutes ago, Kolk1604 said:

Just concerned about temps that's all. 

It does get good by Friday though 

I wouldn’t worry to much about temp if we got a heavy shower. Last year I had accumulating snow in April lol. I am more worried about the low placement 

[Gradient Keeper]

Sorry I've been busy working on music.

Night Shift 6z GFS
Careful analysis of the 500mb pattern is nearly unchanged Day 1-3. The arctic trough is a slight notch further southwest. 850s are even a notch colder yet. Gorge -19c to -21c! Seattle, Bellingham -13c. Olympia -12c. PDX -9c. I tend to think that's about the max potential for this air mass given the trajectory of the arctic trough, general southeastward movement of the bitter cold, and position of offshore ridge. I don't believe we'll see the arctic trough dig any further west the next 3-4 runs. We shall see though.

East wind storm potential is through the roof. PDX-DLS -13 to -15mb! OTH-GEG Cross Cascade -30 to -32mb. I don't know if either of those will verify, but the GFS/ECMWF has been real persistent with solid run-to-run consistency. Should models continue to show this I'd expect the NWS to discuss this fairly soon.

[Skagit Weather]

We're now within about 24 hours of the start of the storm. It looks like the worst model for my area is the UKMET which shows 3-4" (technically the 12km NAM is the worst showing nothing here, but considering the 3km shows 6" here I'm going to discount it for now). Using my new "Disappointment Avoidance Minimum Number" for snow where I subtract 2" from the worst forecast for every 24 hours we are from the start of the event, I get a minimum snowfall of 1-2" on Tuesday which sounds great to me! If all these 6-8" forecasts completely fail and I get nothing I guess we'll have to take into account that we can't ignore the 12km NAM.

Looks like Seattle is in the same boat with the Euro being the limiting model (shows the least amount of snow with 3-4") so it probably should have an equivalent minimum number of 1-2". Hopefully my methodology doesn't have to be refined after Tuesday.

[Gradient Keeper]

Night Shift 6z GEFS

Day 2 (4-run trend) Arctic trough a few notches southwest.

[Gradient Keeper]

Let's see if arctic air punches in more quickly, or further southwest. The answer is YES.

Day 2.5 850s (4-run trend)

[Gradient Keeper]

Day 3 850s (4-run trend) Simply amazing. The models aren't only continuing to trend progressively colder every run, but the arctic air is not backing off with how fast it blasts southward.

[Gradient Keeper]

Day 3.5 850s (4-run trend)

[Kolk1604]

Not to distract anyone or to look ahead, but the GFS is so wet 

[Gradient Keeper]

Low level cold is insane. Unbelievable. 4 PM Thursday PDX 12!

[Gradient Keeper]

1 minute ago, Kolk1604 said:

Not to distract anyone or to look ahead, but the GFS is so wet 

It's amazing how we go right into a very active pattern, powerhouse jet, monster troughs, and wind storm pattern potentially.

[Gradient Keeper]

Are models realizing the sheer magnitude of this arctic air mass and catching up now as runs just trend colder and colder. I think so.

[Christensen87]

3 minutes ago, Gradient Keeper said:

Are models realizing the sheer magnitude of this arctic air mass and catching up now as runs just trend colder and colder. I think so.

Thanks for posting everything, you do a great job. Looks like we’re in for a fun week of winter weather ahead! 

[Gradient Keeper]

2 minutes ago, Christensen87 said:

Thanks for posting everything, you do a great job. Looks like we’re in for a fun week of winter weather ahead! 

Thanks appreciate it! Yes indeed and it just goes right into January! A matter of time before a blocking pattern returns perhaps 2nd-3rd week of January for more Cold and SNOW!!!!

[Gradient Keeper]

Arctic front just east of Arlington(Oregon) now.

[Gradient Keeper]

Arctic front now through Arlington!

[ShawniganLake]

Puntzi Mountain in Central BC is down to -44F. 

[Gradient Keeper]

Current IR/WV Imagery. Hmmm, this looks like jet suppression to me. I could be wrong.

[The Blob]

So if freezing rain does happen, when is the timing for that to start? I'm trying to decide if I want to risk going to work and possibly getting stuck or staying home. 

[thickhog]

1 hour ago, Gradient Keeper said:

Day 3.5 850s (4-run trend)

Really need that to keep trending south. Day 4 850s feel like the only trend worth watching on those 12z runs.

[thickhog]

It’s currently 42F in Rufus, OR (just east of the Dalles). 20 miles to the east it’s 25F. 

[Meatyorologist]

Holy shizzz. Just peeked at the 06z suites, and what I see is pretty incredible. This could be a very, very major snowstorm for Seattle. Lots of lift and saturation in the DGZ, and powerful rates for keeping precip type as snow Tacoma north.

Gawd, maybe even some thundersnow??? And with the track this close, I could see lots of snow falling around brief rain, even if it does occur. And then there's the PSCZ fun immediately after into Wednesday evening. And the harsh cold to follow. FUN

[Meatyorologist]

A lot is changing though as the low forms right now. Going to be a last minute adjustment north it seems, based off the HRRR.

[Meatyorologist]

12z HRRR is massive sad crap

[snow maniac]

No snow here overnight, only a couple flurries.

[Meatyorologist]

HRRR does have one hell of an anafrontal push though. And a Strait surge snow squall! That I would have to see in person.

[Prairiedog]

Just saw Rod Hill's forecast for PDX.  Sheesh.  Pretty puzzled on that one.  Wed is 32/39 dry, Thurs east winds 25/40 dry, Friday 28/40 and as he mentioned, several hours of ZR before it warms up.   

Only even remote possibility of snow was a wintery mix on Tues 22/40 but mostly rain.  Haven't caught up on all the posts and models.  Did I miss something here?  GFS put its foot down again?  Or, he mixed up last weeks GFS models with yesterdays.  I obviously missed something. 

[thickhog]

Just now, Prairiedog said:

Just saw Rod Hill's forecast for PDX.  Sheesh.  Pretty puzzled on that one.  Wed is 32/39 dry, Thurs east winds 25/40 dry, Friday 28/40 and as he mentioned, several hours of ZR before it warms up.   

Only even remote possibility of snow was a wintery mix on Tues 22/40 but mostly rain.  Haven't caught up on all the posts and models.  Did I miss something here?  GFS put its foot down again?  Or, he mixed up last weeks GFS models with yesterdays.  I obviously missed something. 

The moisture for us comes on Friday, when the 850s are too warm, which = ZR. The models have consistently shown PDX getting screwed, so nothing has changed in that regard. More low-level cold on Thu/Fri, I guess.

[Gradient Keeper]

5 minutes ago, Prairiedog said:

Just saw Rod Hill's forecast for PDX.  Sheesh.  Pretty puzzled on that one.  Wed is 32/39 dry, Thurs east winds 25/40 dry, Friday 28/40 and as he mentioned, several hours of ZR before it warms up.   

Only even remote possibility of snow was a wintery mix on Tues 22/40 but mostly rain.  Haven't caught up on all the posts and models.  Did I miss something here?  GFS put its foot down again?  Or, he mixed up last weeks GFS models with yesterdays.  I obviously missed something. 

I have no idea what he's talking about. There isn't a single model run anywhere near that warm. Even the 'warmest' solutions keeps PDX below freezing Thursday and Friday. Moisture is a wildcard more likely showing up late Thursday. If we don't lose the east winds a big ice storm is possible into Christmas Eve.

12z GFS in 1 hour 39 minutes

[Prairiedog]

4 minutes ago, thickhog said:

The moisture for us comes on Friday, when the 850s are too warm, which = ZR. The models have consistently shown PDX getting screwed, so nothing has changed in that regard. More low-level cold on Thu/Fri, I guess.

I never thought we'd see much snow out of this.  I get the 850's warming up.  I've said that several times the last couple days.  It's the temps I'm puzzled about.  39  being our coldest high?  Where's the CAA?  That goes against pretty much everything I've seen. 

[SilverFallsAndrew]

Looks like NWS is going with a low of 17 at PDX on Thursday morning and a high of 24. 19/33 on Friday. 
 

For SLE 22/28, 22/38

Thursday highs very likely at midnight. I’m really starting to be suspicious about many places warming up before Sunday now… 

[Meatyorologist]

NAM has a nearly identical track as its 06z run with sped up timing and a stronger low.

[Gradient Keeper]

2 minutes ago, SilverFallsAndrew said:

Looks like NWS is going with a low of 17 at PDX on Thursday morning and a high of 24. 19/33 on Friday. 
 

For SLE 22/28, 22/38

Thursday highs very likely at midnight. I’m really starting to be suspicious about many places warming up before Sunday now… 

Me too. I'll be surprised unless the east wind backs off. Watch it continues through Christmas now.

[SilverFallsAndrew]

1 minute ago, Gradient Keeper said:

Me too. I'll be surprised unless the east wind backs off. Watch it continues through Christmas now.

This is a weird one. I hope we get a traditional arctic blast later on this winter, but beggars can’t be choosers. 

[SilverFallsAndrew]

Wow looks like Medford hit at least 20 this morning and 19 on a 5 min ob. Low level cold potentially starts moving back in after New Years. Can’t wait. 

[Meatyorologist]

Watching this NAM roll out is like watching someone defuse a bomb