Part I - January 2020 Weather Discussion for the PNW

[Chewbacca Defense]

Positive splat test here in Bellingham at 3-400 ft

[GHweatherChris]

Do you mind explaining? I have yet to learn what to look for with these things

The animated satellite to me shows the system moving very quickly.

[bainbridgekid]

Wednesday morning to Thursday night on the 18z:

 

[snow_wizard]

Nice 18z run.  I hope this puts a smile on people's faces!

 

 

[VancouverIslandSouth]

This is just incorrect.

 

Its will be a classic c-zone on Sunday evening.  The low departs to the east and there is a convergence of wind from the north and the southwest around the Olympics.  

 

 

 

 

Well that's what the ECMWF is showing, not what the 18z GFS is showing. But in both cases the difference being outflow spilling out of the Fraser Valley. Typically a c-zone is triggered by NW flow down the Juan de Fuca meeting up with SW flow from the Chehalis Gap.

[snow_wizard]

Wednesday morning to Thursday night on the 18z:

 

gfs_mslp_pcpn_frzn_nwus_fh96-132.gif

 

This is looking a lot better.  Even the 12z Euro was starting to move toward this outcome.  It stays cold for a bit afterward too so we can enjoy it if it happens.

[runninthruda206]

And just like that, we're back hahaha!..

[snow_wizard]

Well that's what the ECMWF is showing, not what the 18z GFS is showing. But in both cases the difference being outflow spilling out of the Fraser Valley. Typically a c-zone is triggered by NW flow down the Juan de Fuca meeting up with SW flow from the Chehalis Gap.

 

Yeah....Arctic air will be in play this time.  Really ups the stakes.

[fubario]

Nice 18z run.  I hope this puts a smile on people's faces!

Ok, Tim's turn.

[snow_wizard]

And just like that, we're back hahaha!..

 

Nice to see the momentum shift at this juncture.  We might be just fine.

[TT-SEA]

Well that's what the ECMWF is showing, not what the 18z GFS is showing. But in both cases the difference being outflow spilling out of the Fraser Valley. Typically a c-zone is triggered by NW flow down the Juan de Fuca meeting up with SW flow from the Chehalis Gap.

Its the same result. It's a very traditional c-zone signature.

[snow_wizard]

Ok, Tim's turn.

 

I think he conceded the 18z is better, at least for the mid week thing.

[Timmy]

Nice 18z run. I hope this puts a smile on people's faces!

zoom out even more and it looks ever better

[BLI snowman]

You don't think the Monday evening system has much potential?

 

Not really. Maybe a brief isothermal situation east of I-5 with the quick NW wind surge. Probably will have a tough time going below 34 or so at the valley floor. You'll do well, but then even for the central valley I think the potential with the mid-week storm is just better below 500'. 

[van city]

Definitely more snow for the Seattle area on Thursday... 

 

Always 5 days away.

[TT-SEA]

I think he conceded the 18z is better, at least for the mid week thing.

I am not arguing... looked better to me. I posted a couple improved snowfall maps.

 

Matt made some comments. Not me.

[BLI snowman]

Nice to see the momentum shift at this juncture.  We might be just fine.

 

I don't think one slightly improved run constitutes a trend or a momentum shift. Especially when it's the 18z, which as dewey pointed out, has been consistently running cooler than the 12z or 00z.

[van city]

Nice 18z run.  I hope this puts a smile on people's faces!

Until next run.

[Deweydog]

Tomorrow’s,18z guys.

 

And Tuesday night’s 00z, to a lesser extent.

[TT-SEA]

And if the 18Z looked worse... I would have mentioned that as well.

[bainbridgekid]

Always 5 days away.

Did you get any snow there Friday? Not sure of your elevation, but looked like much of Vancouver was likely to get some.

 

I'm also quite sure you'll get snow tomorrow afternoon.

[van city]

Did you get any snow there Friday? Not sure of your elevation, but looked like much of Vancouver was likely to get some.

 

I'm also quite sure you'll get snow tomorrow afternoon.

Sloppy inch, does it count?

[snow_wizard]

I don't think one slightly improved run constitutes a trend or a momentum shift. Especially when it's the 18z, which as dewey pointed out, has been consistently running cooler than the 12z or 00z.

 

Fair enough.  It does kind of match up with the track record of the early cold events we had though.  Those all featured a last minute improvement late in the game and then verification was even slightly better than runs less than a day out.  At this juncture just a small improving trend could have big implications.  Can't wait to see what the 0z runs show.

[runninthruda206]

What time does the 18z euro run?

[van city]

[bainbridgekid]

Sloppy inch, does it count?

It all counts!

 

Assuming you don't have much elevation, then? Saw some pictures that looked like 4-5 inches from the hills in Vancouver.

 

I would think you'd get 3-5" tomorrow which won't melt for for quite a while.

[OysterPrintout]

Tomorrow’s,18z guys.

 

And Tuesday night’s 00z, to a lesser extent.

 

does the UKMET run an 18z 

[Christensen87]

Winter Storm Watch!

[snow_wizard]

Jim, you promised me Historic Cold snap that I have never seen before. What happened?

 

The Alberta PV was forecasted to drive further south with earlier model runs.  All of the models showed that very cold scenario a couple of days ago.  Kind of a bummer.  I was ready for some face stinging cold.

[Deweydog]

does the UKMET run an 18z

If it doesn’t it should.

 

On a related note, if I were in the model business I’d do my runs at 5z, 11z, 17z and 23z. Get a jump on the competition!

[SilverFallsAndrew]

Not really. Maybe a brief isothermal situation east of I-5 with the quick NW wind surge. Probably will have a tough time going below 34 or so at the valley floor. You'll do well, but then even for the central valley I think the potential with the mid-week storm is just better below 500'. 

 

Makes sense. 

 

I agree about the mid-week system. I will likely be warm nosed at some point. It looks like it would turn back to snow after about 12-24 hours as cooler air aloft works back in, though by then it is just showers. My expectations up here haven't really changed much for the mid-week storm. Even when the models were showing highs in the mid-20s at SLE they were showing at least brief periods in the 33/34 range up here. 

 

We just are not typically as cold in outflow based situations. Even in December 1968 the high at Silver Falls was 30 the day Salem had a high of 16. 

[OysterPrintout]

If it doesn’t it should.

 

On a related note, if I were in the model business I’d do my runs at 5z, 11z, 17z and 23z. Get a jump on the competition!

 

You see two models on the shelf one says 12z one says 11z which one do you choose? Duhhh the 11z!

[bainbridgekid]

Winter Storm Watch just issued for most of Western Washington, including Seattle.

 

URGENT - WINTER WEATHER MESSAGE
National Weather Service Seattle WA
246 PM PST Sat Jan 11 2020

WAZ507-509-511-556-558-559-121200-
/O.NEW.KSEW.WS.A.0002.200112T2300Z-200113T1400Z/
Everett and Vicinity-Tacoma Area-Hood Canal Area-
Bellevue and Vicinity-Seattle and Vicinity-Bremerton and Vicinity-
including Everett, Lynnwood, Marysville, Stanwood, Tacoma, Fife,
DuPont, Puyallup, Shelton, Seabeck, Belfair, Brinnon, Bellevue,
Bothell, Kenmore, Mill Creek, Clearview, Kirkland, Newcastle,
Redmond, Sammamish, Issaquah, Seattle, White Center, Tukwila,
Renton, Burien, Des Moines, Kent, Federal Way, Bremerton,
Poulsbo, and Indianola
246 PM PST Sat Jan 11 2020

...WINTER STORM WATCH IN EFFECT FROM SUNDAY AFTERNOON THROUGH
LATE SUNDAY NIGHT...

* WHAT...Heavy snow possible. Total snow accumulations of a trace
to 2 inches possible with locally up to 4 inches.

* WHERE...Seattle, Everett, Bellevue, Bremerton, Tacoma and
vicinity.

* WHEN...From Sunday afternoon through late Sunday night.

* IMPACTS...Travel could be very difficult.

* ADDITIONAL DETAILS...A trace to 2 inches of snowfall possible
with lowest amounts near the sound. Higher amounts possible,
locally up to 4 inches, if heavier showers develop.

[snow_wizard]

Winter Storm Watch!

 

Yes indeed!

 

Even with the C-Zone probably being north of where I live it appears there will be sufficient moisture for a more widespread snow event for the Puget Sound area late Sunday night.  We could see a sliding C-zone happen too.

[SilverFallsAndrew]

A nice coolish trough late next week in the long range. 

[runninthruda206]

WSW!!! Please work in our favor

[Frontal Snowsquall]

Definitely more snow for the Seattle area on Thursday...

 

Not bad.

[TT-SEA]

Winter Storm Watch just issued for most of Western Washington, including Seattle.

 

URGENT - WINTER WEATHER MESSAGE

National Weather Service Seattle WA

246 PM PST Sat Jan 11 2020

 

WAZ507-509-511-556-558-559-121200-

/O.NEW.KSEW.WS.A.0002.200112T2300Z-200113T1400Z/

Everett and Vicinity-Tacoma Area-Hood Canal Area-

Bellevue and Vicinity-Seattle and Vicinity-Bremerton and Vicinity-

including Everett, Lynnwood, Marysville, Stanwood, Tacoma, Fife,

DuPont, Puyallup, Shelton, Seabeck, Belfair, Brinnon, Bellevue,

Bothell, Kenmore, Mill Creek, Clearview, Kirkland, Newcastle,

Redmond, Sammamish, Issaquah, Seattle, White Center, Tukwila,

Renton, Burien, Des Moines, Kent, Federal Way, Bremerton,

Poulsbo, and Indianola

246 PM PST Sat Jan 11 2020

 

...WINTER STORM WATCH IN EFFECT FROM SUNDAY AFTERNOON THROUGH

LATE SUNDAY NIGHT...

 

* WHAT...Heavy snow possible. Total snow accumulations of a trace

to 2 inches possible with locally up to 4 inches.

 

* WHERE...Seattle, Everett, Bellevue, Bremerton, Tacoma and

vicinity.

 

* WHEN...From Sunday afternoon through late Sunday night.

 

* IMPACTS...Travel could be very difficult.

 

* ADDITIONAL DETAILS...A trace to 2 inches of snowfall possible

with lowest amounts near the sound. Higher amounts possible,

locally up to 4 inches, if heavier showers develop.

Kiss. Of. Death.

 

No joke.

[Deweydog]

You see two models on the shelf one says 12z one says 11z which one do you choose? Duhhh the 11z!

[GHweatherChris]

Winter Storm Watch just issued for most of Western Washington, including Seattle.

 

URGENT - WINTER WEATHER MESSAGE

National Weather Service Seattle WA

246 PM PST Sat Jan 11 2020

 

WAZ507-509-511-556-558-559-121200-

/O.NEW.KSEW.WS.A.0002.200112T2300Z-200113T1400Z/

Everett and Vicinity-Tacoma Area-Hood Canal Area-

Bellevue and Vicinity-Seattle and Vicinity-Bremerton and Vicinity-

including Everett, Lynnwood, Marysville, Stanwood, Tacoma, Fife,

DuPont, Puyallup, Shelton, Seabeck, Belfair, Brinnon, Bellevue,

Bothell, Kenmore, Mill Creek, Clearview, Kirkland, Newcastle,

Redmond, Sammamish, Issaquah, Seattle, White Center, Tukwila,

Renton, Burien, Des Moines, Kent, Federal Way, Bremerton,

Poulsbo, and Indianola

246 PM PST Sat Jan 11 2020

 

...WINTER STORM WATCH IN EFFECT FROM SUNDAY AFTERNOON THROUGH

LATE SUNDAY NIGHT...

 

* WHAT...Heavy snow possible. Total snow accumulations of a trace

to 2 inches possible with locally up to 4 inches.

 

* WHERE...Seattle, Everett, Bellevue, Bremerton, Tacoma and

vicinity.

 

* WHEN...From Sunday afternoon through late Sunday night.

 

* IMPACTS...Travel could be very difficult.

 

* ADDITIONAL DETAILS...A trace to 2 inches of snowfall possible

with lowest amounts near the sound. Higher amounts possible,

locally up to 4 inches, if heavier showers develop.

I wouldn't say most, maybe most populated areas but nowhere near most of the westside.