Part I - January 2020 Weather Discussion for the PNW

[Winterdog]

According to this map it’s a good thing I moved back in 2018!

Yeah it looks like I'm in the 3 to 4" range myself.  Being quite a ways east of I-5 offsets a lot of elevation.  I'm under 300' which is nearly 200' lower than Sea-Tac but kick Sea-Tac's butt most of the time.

[SilverFallsAndrew]

Portland is even more impressive in the LR. 10 days in the 20s.

 

 

January 1930 redux?!

[snow_wizard]

I wouldn't worry too much about the east wind precip inhibition being shown on this run for the ESPL later next week.  We have no idea how the low will track yet.  The 12z Euro run showed plenty for us.  Besides I'm really liking what I'm seeing for snow at the very beginning of the event anyway.

[MossMan]

Total snow from 10AM Sunday-10AM Monday... Certainly better for the central Puget Sound than the 12z and 18z.

 

I really hope that changes.

[snow_wizard]

ECMWF 00z looking better for Seattle late Sunday night and early Monday morning. C-zone develops behind the low.

 

EPSL does very well with backwash behind lows taking the track shown on the GFS.  Haven't seen the Euro yet.

[Frontal Snowsquall]

Low is a bit further south

I wouldn't mind that if it helps build a stronger cold pool.

[Perturbed Member]

splitting hairs but that’s rain at pdx

 

Whatever it is, yeah it is 0 snow. Switches to all rain during the day as temps warm. 

 

I think if the low tracks just right there could be a shot Monday night-Tuesday of stickage but otherwise all hope is probably on Wednesday for PDX.

[VancouverIslandSouth]

So close, need that sucker to come a little further south. Still an improvement with the low over the previous ECMWF runs and very close to what the GFS is showing now. One thing seems clear, East Vancouver Island is going to get absolutely nailed with that Sunday storm.

 

[Cloud]

Total snow from 10AM Sunday-10AM Monday... Certainly better for the central Puget Sound than the 12z and 18z.

 

A solid 2" to 2.5" over me. Like it. 

[Winterdog]

Total snow from 10AM Sunday-10AM Monday... Certainly better for the central Puget Sound than the 12z and 18z.

 

 

Wow.  Now I just went from 4" on the WRF to a half inch on the Euro.  

[bainbridgekid]

Total snow from 10AM Sunday-10AM Monday... Certainly better for the central Puget Sound than the 12z and 18z.

 

That is a very strong Convergence Zone signature along the arctic front.

 

Experience tells us those usually form initially further North than modeled and tend to hang around and slide South slower than modeled. Would benefit most of us if that holds true this time.

[Weiner Warrior]

Winter cancelled. Going back to bed

[TacomaWaWx]

Total snow from 10AM Sunday-10AM Monday... Certainly better for the central Puget Sound than the 12z and 18z.

 

My house does good alot of times when these c-zones drop down south. Good news for me.

[wxmet]

ECMWF out to 120hr looks much stronger with the offshore low at the same longitude than it did from yesterday's 00z run. Also the PV isn't as far west.

[TT-SEA]

That is a very strong Convergence Zone signature along the arctic front.

 

Experience tells us those usually form initially further North than modeled and tend to hang around and slide South slower than modeled. Would benefit most of us if that holds true this time.

 

 

I think that will behave more like a traditional c-zone behind a departing low.    Its not a traditional arctic front.  

 

The c-zone will just form in its usual spot and move south and then dissolve.

[Winterdog]

Winter cancelled. Going back to bed

I'm with you on that.. ehh, well you know what I mean.

[MossMan]

I think that will behave more like a traditional c-zone behind a departing low. Its not a traditional arctic front.

 

The c-zone will just form in its usual spot and move south and then dissolve.

Hopefully it forms over my house like it usually does.

[wxmet]

Regional event early Wednesday morning. ECMWF has moved up the time frame quite a bit.

[TT-SEA]

ECMWF shows a high of only 24 in Seattle on Tuesday... and basically dry.

[Frontal Snowsquall]

Regional event early Wednesday morning. ECMWF has moved up the time frame quite a bit.

Here she comes!

 

[seattleweatherguy]

ECMWF shows a high of only 24 in Seattle on Tuesday... and basically dry.

And lows in the teens?

[MR.SNOWMIZER]

I think that will behave more like a traditional c-zone behind a departing low. Its not a traditional arctic front.

 

The c-zone will just form in its usual spot and move south and then dissolve.

So what you are saying is you already have the front resolved even before the models. Get the **** out of here. Lol

[Omegaraptor]

Backdoor blast reaches PDX at the same time as the 12z.

[Frontal Snowsquall]

Colder at 850mb too.

 

Yeah, trended colder.

[Perturbed Member]

Doesn't look like the euro has turned this system toothless like the 00z GFS did. 

[luvssnow_spokane]

And lows in the teens?

probably colder for lows in some spots. 

[TT-SEA]

So what you are saying is you already have the front resolved even before the models. Get the **** out of here.

 

 

I am telling you that precip signature that pounds the Cascades and foothills is due strong onshore flow behind the departing low.    And it will be the usual wavering c-zone situation and not a single band of precip moving southward.

 

That low is pulling down cold air... but the strong onshore flow is what is driving the precip behind the low.

 

With a true arctic front... there is less precip in the foothills and Cascades.   

[Requiem]

Uh....trended south, apparently...

[Frontal Snowsquall]

Wednesday afternoon

 

[Timmy]

Big pdx snow maker

[bainbridgekid]

I think that will behave more like a traditional c-zone behind a departing low.    Its not a traditional arctic front.  

 

The c-zone will just form in its usual spot and move south and then dissolve.

How do you figure?

 

Looks like a fairly similar setup as other Arctic Front/CZ's we've seen recently (11/27/06, 1/10/07, 12/18/08, 11/22/10, etc.)

 

I can't remember a single time when an incoming arctic blast set off a CZ around or South of Seattle without giving snow to Skagit or Snohomish County first and I remember many times when it took longer to slip South than modeled. No guarantee that will be the case this time, but I'm just interested in your rationale.

[Omegaraptor]

Euro seems to be incapable of keeping the cold in the eastern part of the Columbia Basin for some reason. 

[TigerWoodsLibido]

North valley special.

[Perturbed Member]

Drier so far for sure

12z vs 00z

 

[bainbridgekid]

I am telling you that precip signature that pounds the Cascades and foothills is due strong onshore flow behind the departing low.    And it will be the usual wavering c-zone situation and not a single band of precip moving southward.

 

That low is pulling down cold air... but the strong onshore flow is what is driving the precip behind the low.

 

With a true arctic front... there is less precip in the foothills and Cascades.   

It's both.

 

Almost every moist arctic front is proceeded by strong onshore flow that gives the foothills and Cascades a bunch of snow.

[SilverFallsAndrew]

Seattle is going to see a cold blast for sure. So jelly

[TT-SEA]

That surface low just spins up on Wednesday morning in place.   Its not really moving in... the precip just forms rapidly in an arc.

 

[Perturbed Member]

24 hr precip 12z vs 00z. This is pretty much exactly what the 00z GFS also did. Much drier.

 

 

[OysterPrintout]

MULTIBALL except with lows

 

[Requiem]

I mean....still fine, but the gutting of the precip is a bad sign. Better hope that quits.