January 2017 Observations and Model Discussion for the Pacific Northwest

[Perturbed Member]

Looks like the GFS doesn't think we go below freezing until around 9-10 PM here, light precip shows up around 4PM. The cooler air better show up here via the gorge on time or bad things will happen to this event. 

[Kayla]

I knew it wasn't true but I also pointed out what it was showing. For any valley forecasts I wouldn't trust the tropical tidbits snowfall Maps, they seem to have extreme resolution issues, it seems to always have at least a trace over pdx when snow levels in reality are over 1000'. The gem appears to be even worse with that. The wx bell Maps seem to deal with that issue well.

 

Yeah I'm only referencing the wx bell maps. 

[Deweydog]

Looks like the GFS doesn't think we go below freezing until around 9-10 PM here, light precip shows up around 4PM. The cooler air better show up here via the gorge on time or bad things will happen to this event.

That's an aspect that can't be ignored with this. The GFS is almost invariably too aggressive with back door cold advection. A 2-3 hour difference could affect accumulations quite a bit either way.

[BLI snowman]

7pm!

 

Seems about the consensus right now.

[SilverFallsAndrew]

There won't be a lot of cold air from the gorge. It supposedly transitions due to cool air from the gorge and a somewhat isothermal column as the airmass cools. The gorge won't be much below freezing...

[Kayla]

Looks like the GFS doesn't think we go below freezing until around 9-10 PM here, light precip shows up around 4PM. The cooler air better show up here via the gorge on time or bad things will happen to this event. 

 

Gorge outflow is going to really ramp up by early this afternoon and that gorge is still quite chilly/snowy so the source is good.

[Kayla]

That's an aspect that can't be ignored with this. The GFS is almost invariably too aggressive with back door cold advection. A 2-3 hour difference could affect accumulations quite a bit either way.

 

Yeah it will be interesting if areas can begin to pick up some accumulations with the main band as it shifts north. The NAM obviously thinks we do but as you say it's a tough call at this point.

[HighlandExperience]

What happened in the Puget Sound this AM does not bode well for widespread, major accumulations further south this PM. Gonna be another close call, but I'm doubtful about much south of Portland below 500', and places with good outflow tap near the Gorge probably have the best shot in Portland area.

It is a bad omen. Portland NWS best play it conservative right now. WRF really doesn't show much snow down that way.

[Kayla]

There won't be a lot of cold air from the gorge. It supposedly transitions due to cool air from the gorge and a somewhat isothermal column as the airmass cools. The gorge won't be much below freezing...

 

But it's very snow covered so that always helps.

[VancouverIslandSouth]

Just a trace here overnight. Down to 30 now but just cloudy.

 

There was just enough to cover most untreated surfaces around here, but I imagine it will sublimate quickly. Mixed sun/cloud here and hovering around 31F now with strong NE winds. Things are looking better down toward Port Angeles, but it will be tough for any precip to overcome the outflow. 

 

http://i131.photobucket.com/albums/p286/jemeric/IMG_3808_zpsfs2fo3kd.jpg

[Perturbed Member]

GEM...someone post the weatherbell version if possible.

GEM http://www.tropicaltidbits.com/analysis/models/gem/2017011012/gem_asnow_nwus_8.png

[Kayla]

GEM...someone post the weatherbell version if possible.

GEM http://www.tropicaltidbits.com/analysis/models/gem/2017011012/gem_asnow_nwus_8.png

 

[BLI snowman]

Canadian shows the transition beginning around 10pm..

 

 

 

[HighlandExperience]

GEM...someone post the weatherbell version if possible.

GEM http://www.tropicaltidbits.com/analysis/models/gem/2017011012/gem_asnow_nwus_8.png

Looks nice but the GEM is laughable right now. The GEM snowmap from last night showed 2-3 inches over King County

[TT-SEA]

Live view up here this morning...

 

[Perturbed Member]

PDX NWS thinks there is a bit too much uncertainty in the temps 

 

"This is not a slam dunk winter weather event as there is not an

obvious cold air mass in place like the last one. Some areas may see
more snow than forecasted, and others much less or none. Forecasting
where these locations are will depend on where the low actually moves
onshore. Currently the models project that the low will move onshore
near Newport, Oregon. Models tend to under forecast precipitation for
areas north of the low, and I have went slightly above model guidance
for QPF in areas north of Newport."

[Deweydog]

But it's very snow covered so that always helps.

The snow cover really is a non-factor in a setup like this. Low level cold isn't the issue, it's a matter of cooling the column from the top down as cold air advects from several thousand feet up.

 

The snow cover will be more relevant the rest of the week as offshore flow becomes low level.

[TT-SEA]

I see the sun is shining up in Bellingham... with 29/11 and N22G38.   Fraser River outflow in full force.

[Timmy]

PDX NWS thinks there is a bit too much uncertainty in the temps

 

"This is not a slam dunk winter weather event as there is not an

obvious cold air mass in place like the last one. Some areas may see

more snow than forecasted, and others much less or none. Forecasting

where these locations are will depend on where the low actually moves

onshore. Currently the models project that the low will move onshore

near Newport, Oregon. Models tend to under forecast precipitation for

areas north of the low, and I have went slightly above model guidance

for QPF in areas north of Newport."

This is actually an agreeable forecast.

[Perturbed Member]

Looks nice but the GEM is laughable right now. The GEM snowmap from last night showed 2-3 inches over King County

 

Yeah I did notice the quite unrealistic totals up there. Doesn't seem like the GEM has been too good this winter. 

[Kayla]

The snow cover really is a non-factor in a setup like this. Low level cold isn't the issue, it's a matter of cooling the column from the top down as cold air aspects from several thousand feet up.

 

The snow cover will be more relevant the rest of the week as offshore flow becomes low level.

 

But low level level outflow can cool the column up to around 925mb right? 850s seem fine.

[TT-SEA]

Rain has turned to snow down in the valley here at 400 feet.

[BLI snowman]

I see the sun is shining up in Bellingham... with 29/11 and N22G38.   Fraser River outflow in full force.

 

It's reached Port Angeles as well, 32 with snow there. Still could be a close call for areas like Olympia with seeing a switchover.

[Deweydog]

But low level level outflow can cool the column up to around 925mb right? 850s seem fine.

Troutdale or Washougal could see a quicker changeover I suppose, but as Andrew pointed out the air immediately within the gorge is not particularly cold at the moment. Cold air advection is just now making its way into the basin.

[TT-SEA]

It's reached Port Angeles as well, 32 with snow there. Still could be a close call for areas like Olympia with seeing a switchover.

 

 

Also looks like its filtering into Seattle with a north wind there.   Precip around Seattle is just fading away now as the deformation band appears to be re-grouping farther south.

 

Cold air will push out that pesky precip before it can turn to snow.   Perfect!  

[Kayla]

Troutdale or Washougal could see a quicker changeover I suppose, but as Andrew pointed out the air immediately within the gorge is not particularly cold at the moment. Cold air advection is just now making its way into the basin.

 

Okay yeah. Will be interesting to keep an eye on the meso data as we progress into the afternoon. Should give us a better idea on when the changeover will occur. Definitely need the basin to cool down at the 925mb level as the outflow begins to help us out all that much.

[Timmy Supercell]

Some off/on periods of decent sized flakes, more than light at times. Too bad it's still well above freezing. Same accumulation since my midnight measurement. (3")

[Blizzard777]

Looking at a few stations with downward trend in temps heading south!

[Timmy Supercell]

Ha, noticed KLMT reports rain last couple observations. My additional few hundred feet on the hill sometimes makes that much of a difference. The flakes outside don't lie to me.

[Perturbed Member]

All models show some pretty good CAA in the basin. GFS shows temps around 30-32F there around 1PM today dropping  to the 15F-18F range by 10 PM tonight. More or less all the models show a similar thing. NAM is more aggressive with the cold and has PDX down to freezing by around 7.

[MossMan]

Glad I didn't make my weekly trip east today...looking a little rough between Snoqualmie pass and Yakima currently which was going to be my work trip. 

[Jesse]

Looking at a few stations with downward trend in temps heading south!

 

Another antarctic front!

[TT-SEA]

Getting more rain/snow mix here. Temp at 34 degrees.

 

 

Sky is getting bright here... looks like sun is coming out just north of King County now.

[Jesse]

PDX sitting at 36 right now with ESE winds. With that cloud band approaching from the south and offshore flow not really going anywhere I don't see them getting to 40 today. Not much of a drop in temp is really needed for sticking snow at this point!

[Blizzard777]

35.8 here with light rain. Clouds moving along pretty quick southbound

[MossMan]

Sunny clear skies here in Stanwood now! 

[MikeInEverett]

[Kayla]

Looks like the latest HRRR continues to insist the changeover begins at 6-7pm at PDX.

[Phil]

Interesting to note that the upcoming +EAMT/NPAC jet extension will blow away anything observed during last winter's super niño event. Like, it's not even close. SoCal/SW US will be cashing in big time over the next 10-15 days.

 

Huge changes upcoming during late January, though, partially as a result of this regime. We'll have the EAMT/tropical convection reversing phase, partially in response to this NPAC cyclonic regime perturbing the global stratosphere and reducing the tropical static stability, on aggregate, via a cooling of the equatorial tropopause. The NPAC jet will pull back with the cyclonic train shifting into NE Russia and the NW Pacific, placing ideal surf zone across NPAC, which will lead to another round of EPO and/or NAM/polar based blocking.

 

In some respects, this may be similar to the systematic transition from November into December, however, due to differences in the seasonal relationships and alterations to the background state in general, the result will be somewhat different. Will likely be a significant EPO drop, but otherwise, differences likely in WPO domain, possibly NAM/AO as well. Could be less WPO, more EPO/NAM.

 

Will be a fun ride. Eventually models will catch on, assuming I'm correct which is never a given, especially in winters like this.

[MossMan]

Interesting to note that the upcoming +EAMT/NPAC jet extension will blow away anything observed during last winter's super niño event. Like, it's not even close. SoCal/SW US will be cashing in big time over the next 10-15 days.

 

Huge changes upcoming during late January, though, partially as a result of this regime. We'll have the EAMT/tropical convection reversing phase, partially in response to this NPAC cyclonic regime perturbing the global stratosphere and reducing the tropical static stability, on aggregate, via a cooling of the equatorial tropopause. The NPAC jet will pull back with the cyclonic train shifting into NE Russia and the NW Pacific, placing ideal surf zone across NPAC, which will lead to another round of EPO and/or NAM/polar based blocking.

 

In some respects, this may be similar to the systematic transition from November into December, however, due to differences in the seasonal relationships and alterations to the background state in general, the result will be somewhat different. Will likely be a significant EPO drop, but otherwise, differences likely in WPO domain, possibly NAM/AO as well. Could be less WPO, more EPO/NAM.

 

Will be a fun ride. Eventually models will catch on, assuming I'm correct which is never a given, especially in winters like this.

So the Puget Sound area might actually get snow in a few weeks?