PNW December 2022 - Part II

[umadbro]

2 minutes ago, Timmy said:

does the WRF not distinguish ZR/sleet/snow?  or does it actually think its gonna snow?

As far as I know it doesn’t distinguish.

[Terreboner]

NAM is saying "no soup for you!"

 

[Doinko]

5 minutes ago, Timmy said:

does the WRF not distinguish ZR/sleet/snow?  or does it actually think its gonna snow?

They have "modeled snowfall" and "snowfall", where modeled snowfall distinguishes while I think snowfall just shows everything as snow if it's below freezing

[SouthHillFrosty]

I think if the GFS is correct, there would be more snow for Tacoma. A heavy band moves south and just dissipates a little to quickly. Add an extra 1-3 inches if the GFS is correct.  @TacomaWx

[Requiem]

3 minutes ago, Deweydog said:

Yeah, the WRF is pretty bad with these deep cold pool overrunning setups.

What are your thoughts on what'll happen at this point with this airmass moving in? 

[Chewbacca Defense]

Just upgraded to a Winter Storm Warning here.  Currently 15 and it has been snowing most of the day

[KingstonWX]

Winter storm watch updated to a winter storm warning. Let's go!

[Christensen87]

...WINTER STORM WARNING IN EFFECT FROM 7 PM THIS EVENING TO 7 PM
PST TUESDAY...

* WHAT...Heavy snow expected. Total snow accumulations of 2 to 8
  inches.

* WHERE...Portions of northwest and west central Washington.

* WHEN...From 7 PM this evening to 7 PM PST Tuesday.

* IMPACTS...Travel could be very difficult.

* ADDITIONAL DETAILS...A transition to rain is possible across
  King County late tonight into Tuesday morning.

[WildrootParable]

Our precip is back! Very lightly snowing again.  

[Terreboner]

Just now, Christensen87 said:

...WINTER STORM WARNING IN EFFECT FROM 7 PM THIS EVENING TO 7 PM
PST TUESDAY...

* WHAT...Heavy snow expected. Total snow accumulations of 2 to 8
  inches.

* WHERE...Portions of northwest and west central Washington.

* WHEN...From 7 PM this evening to 7 PM PST Tuesday.

* IMPACTS...Travel could be very difficult.

* ADDITIONAL DETAILS...A transition to rain is possible across
  King County late tonight into Tuesday morning.

Right on.  I hope you guys score big time!!!!

[Snownerd3000]

Just now, Christensen87 said:

...WINTER STORM WARNING IN EFFECT FROM 7 PM THIS EVENING TO 7 PM
PST TUESDAY...

* WHAT...Heavy snow expected. Total snow accumulations of 2 to 8
  inches.

* WHERE...Portions of northwest and west central Washington.

* WHEN...From 7 PM this evening to 7 PM PST Tuesday.

* IMPACTS...Travel could be very difficult.

* ADDITIONAL DETAILS...A transition to rain is possible across
  King County late tonight into Tuesday morning.

 

[jakerepp]

9 minutes ago, SouthHillFrosty said:

Yea what airport code is nearby?

KMAN is closest, but KBOI is fine

[SnowPlz]

3 minutes ago, KingstonWX said:

Winter storm watch updated to a winter storm warning. Let's go!

We are looking good here in east Kitsap 

[Terreboner]

Not sure if anyone ever reads these but the "heavy snow" prediction wing of the NWS always has good regional reads.

 

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
356 PM EST Mon Dec 19 2022

Valid 00Z Tue Dec 20 2022 - 00Z Fri Dec 23 2022

...Arctic cold front pushes down the Plains with Blizzard
conditions for portions of the Plains and Midwest...

...Pacific Northwest, Northern Rockies, and Northern High Plains...
Days 1-2...

An upper trough currently over the Gulf of Alaska will wrap around
a deep upper low currently centered over the Canadian Rockies
through Tuesday before shifting southeast down the northern
Rockies and northern High Plains Tuesday night and Wednesday. A
plume of Pacific moisture ahead of the Gulf of Alaska wave will
shift across WA and the northern ID/MT Rockies tonight before
shifting south to northern OR and southern ID/MT Rockies.

Snow levels near sea level and moderate to locally heavy precip
rates along a nearly stationary arctic cold front look to cause
notable accumulations across Washington tonight including the
Seattle metro area along with enhanced snowfall in mountains.
Moderately high Day 1 snow probabilities for over 4 inches are
across the Puget Sound area with high probabilities for a foot or
more for the Olympics and WA Cascades with moderate probabilities
for over 8 inches in the northern ID/MT Rockies including the
Bitterroots.

The favorable upper forcing and strong low-to-mid level
frontogenesis will support heavy mountain snow spreading east from
the Pacific Northwest into the northern and north-central Rockies
Tuesday through Wednesday. Day 2 snow probabilities for more than
8 inches are high again for the Bitterroots as well as the
Absarokas, Tetons, and Wind River Range in WY with 48hr totals in
both these mountainous areas having high probabilities for over 18
inches.

In addition, as the upper trough begins its push southeast down
the northern Rockies Tuesday night the advancing arctic cold front
looks to be accompanied by lines of heavy snow and likely snow
squalls that spread over ID/WY Tuesday night/Wednesday and
possibly northern Colorado late Wednesday. Please see Key messages
below.

By Tuesday afternoon, favorable upper divergence associated with a
left-exit region of a strong NWly 250mb jet streak coming in from
the North Pacific will help spread overrunning precipitation into
the northern High Plains of Montana. Surface temperatures will be
extremely cold and well below zero during this timeframe, which
may actually temper SLRs from exceeding 20 to 1. Day 1.5 snow
probabilities for 6 inches or more are high for much of
west-central Montana mountains and valleys with the Big Belt
Mountains forming much of the eastern boundary.

[TacomaWx]

2 minutes ago, SouthHillFrosty said:

I think if the GFS is correct, there would be more snow for Tacoma. A heavy band moves south and just dissipates a little to quickly. Add an extra 1-3 inches if the GFS is correct.  @TacomaWx

I have a feeling we end up with an inch  or so at the beginning of it. Maybe an Inch in the post low precip but absolutely no idea how this is gonna play out tomorrow. Should get some snow at the very least…but the potential of it being a huge event is also there. 

[bishbish777]

Toppes out at 33 in Wallingford, back down to 32. Sure seems colder than expected! Fingers crossed, this is gonna be extremely close...

[Cloud]

Flurries! 

[SouthHillFrosty]

4 minutes ago, jakerepp said:

KMAN is closest, but KBOI is fine

I can’t pull up the ensembles yet so you’ll have to settle for a zoomed out look. 

[bainbridgekid]

High of 29 so far in Everett. Impressive stuff. Also snowed another 0.5” last night.
 

On my drive to Seatac the temperature went from 27 to 36 so there’s clearly been a weak arctic boundary between there. But now it’s flurrying enough at SEA they’re deicing the plane. 
 

 

[Cold Snap]

Just had a light snow shower move through. Currently 29.

[Deweydog]

7 minutes ago, Requiem said:

What are your thoughts on what'll happen at this point with this airmass moving in? 

The cold is relatively easy at this point. Might roll in a little slower than modeled, which is usually a pretty safe assumption, but advection well into the 20’s (similar to 2004) is probable.

The system is still a tough call, probably more because of QPF compared to precip type. Any window of a frozen column looks to be pretty brief since it will likely start with a decent warm layer that would need to be cooled. That could take place pretty quickly but overall warm advection in the mid levels would also be rolling pretty good at that point.

[LowerGarfield]

After I tweeted at NWS Spokane they said they were working on it. A few hours later they've given me a WWA 3-8 inches for my zone and the Lewiston area zone near us. A bit surprised we don't have a Warning Potential but if I get over three inches in the next two days I'll be happy.

[jakerepp]

7 minutes ago, SouthHillFrosty said:

I can’t pull up the ensembles yet so you’ll have to settle for a zoomed out look. 

Thanks! Friday looks to be the main event here. Looks decent on these maps.

[Requiem]

7 minutes ago, Deweydog said:

The cold is relatively easy at this point. Might roll in a little slower than modeled, which is usually a pretty safe assumption, but advection well into the 20’s (similar to 2004) is probable.

The system is still a tough call, probably more because of QPF compared to precip type. Any window of a frozen column looks to be pretty brief since it will likely start with a decent warm layer that would need to be cooled. That could take place pretty quickly but overall warm advection in the mid levels would also be rolling pretty good at that point.

I know your location gives you some vested interest in easterly strength-- do you have any significant observations on that in the coming days? (Last question I promise) 

[MWG]

Cloudy day!

[Skagit Weather]

This is just a beautiful NWS forecast for my location for the next couple days

[awright-31]

The rain has begun.

[SouthHillFrosty]

Nice ensemble improvement 

[gusky]

Beautiful ensembles today. Winter storm warning issued, sattelite progressing nicely... this is gonna be a doozy of a storm. 

[PuyallupChris]

20 minutes ago, TacomaWx said:

I have a feeling we end up with an inch  or so at the beginning of it. Maybe an Inch in the post low precip but absolutely no idea how this is gonna play out tomorrow. Should get some snow at the very least…but the potential of it being a huge event is also there. 

I hope you're right, but all the maps I'm seeing now, including the NWS alert, show a big glaring "will probably turn to rain" banner from the King-Pierce line south.  That'd be a huge bummer, but we'll see. 

[Ice_is_Everywhere]

The flurries from this morning have turned into drizzles this afternoon. Hopefully that’s not foreshadowing of the main event.

[Deweydog]

Just now, Requiem said:

I know your location gives you some vested interest in easterly strength-- do you have any significant observations on that in the coming days? (Last question I promise) 

Looks traditionally strong for a major outflow event. As the NWS mentions, there’s also some decent slop over signal for the foothills which brings up mountain wave potential given the fact the inversion layer might be pretty deep, at least initially. I’m guessing a wind advisory will get hoisted tomorrow.

[Brian_in_Leavenworth]

PSA:

The NWS always appreciates observations, especially detailed observations that everyone on here is capable of giving.  That can be done thru Twitter, as they often set up a feed for that, or the mPing app.  That can include final snowfall amounts, when the snow starts/stops, precip type, dew point, etc

This helps them with short term forecasts as well as future forecasts as they can learn from them.  A few years ago they had a freezing rain advisory for Leavenworth, but I notified them that the rain was not freezing, temps were above freezing and the roads were fine.  They thanked me and told me that they were able to cancel the zr advisory thanks to my observations.  So yes it helps. 

We all want better forecasts.  Yes, more $ to build better models helps, but the more data they have, the better.  And it can also help to inform the public about conditions.  This will be even more helpful during the possible freezing rain event later this week.   Instead of just complaining about forecasts not verifying, let's be a part of the solution.

[MR.SNOWMIZER]

euro had bellingham at 25 today i think, currently 16. had bremerton at 35 currently 30.

[Doinko]

7 minutes ago, Requiem said:

I know your location gives you some vested interest in easterly strength-- do you have any significant observations on that in the coming days? (Last question I promise) 

I'm really disappointed I'll be missing this east wind storm.

What's the criteria for a HWW? The WRF is forecasting 50mph+ gusts for my location in Bethany in the west metro

 

[Cloud]

2 minutes ago, Brian_in_Leavenworth said:

PSA:

The NWS always appreciates observations, especially detailed observations that everyone on here is capable of giving.  That can be done thru Twitter, as they often set up a feed for that, or the mPing app.  That can include final snowfall amounts, when the snow starts/stops, precip type, dew point, etc

This helps them with short term forecasts as well as future forecasts as they can learn from them.  A few years ago they had a freezing rain advisory for Leavenworth, but I notified them that the rain was not freezing, temps were above freezing and the roads were fine.  They thanked me and told me that they were able to cancel the zr advisory thanks to my observations.  So yes it helps. 

We all want better forecasts.  Yes, more $ to build better models helps, but the more data they have, the better.  And it can also help to inform the public about conditions.  This will be even more helpful during the possible freezing rain event later this week.   Instead of just complaining about forecasts not verifying, let's be a part of the solution.

mPing is an incredible and useful app. I’ve been using it since it first rolled out. 

[runninthruda206]

Only light drizzle, no flurries

[MikeInEverett]

5 minutes ago, gusky said:

Beautiful ensembles today. Winter storm warning issued, sattelite progressing nicely... this is gonna be a doozy of a storm. 

You mind posting Paine Field?

[Rubus Leucodermis]

Snowing the hardest it has all day. Which is still pretty light.

20.8°F.

[WeatherGeek2022]

5 minutes ago, Brian_in_Leavenworth said:

PSA:

The NWS always appreciates observations, especially detailed observations that everyone on here is capable of giving.  That can be done thru Twitter, as they often set up a feed for that, or the mPing app.  That can include final snowfall amounts, when the snow starts/stops, precip type, dew point, etc

This helps them with short term forecasts as well as future forecasts as they can learn from them.  A few years ago they had a freezing rain advisory for Leavenworth, but I notified them that the rain was not freezing, temps were above freezing and the roads were fine.  They thanked me and told me that they were able to cancel the zr advisory thanks to my observations.  So yes it helps. 

We all want better forecasts.  Yes, more $ to build better models helps, but the more data they have, the better.  And it can also help to inform the public about conditions.  This will be even more helpful during the possible freezing rain event later this week.   Instead of just complaining about forecasts not verifying, let's be a part of the solution.

It honestly doesn't appear that more $$ will even help in a seemingly endless evolution process at least concerning snowfall.