January 2016 in the PNW

[Kayla]

There still doesn't seem to be any evidence that Portland will be getting snow, is there? I still think most places will see sleet and freezing rain while some cold pool areas get some snow to start.  

 

Besides the ECMWF, NAM, GEM there is no evidence of snow so we'll just go with our trusty ol'friend the GFS and WRF. Cause it always does spectacular in these types of setups within 24 hours.

[TT-SEA]

Becoming more likely that the Midwest will finally have a solid arctic blast.    

[FroYoBro]

Besides the ECMWF, NAM, GEM there is no evidence of snow so we'll just go with our trusty ol'friend the GFS and WRF. Cause it always does spectacular in these types of setups within 24 hours.

 

I was genuinely asking. I was out watching football since earlier this afternoon. 

 

I'm certainly no expert on close calls like this, so I was curious why everyone was so suddenly bullish for snow. 

[Deweydog]

Besides the ECMWF, NAM, GEM there is no evidence of snow so we'll just go with our trusty ol'friend the GFS and WRF. Cause it always does spectacular in these types of setups within 24 hours.

It generally does pretty well. You may want it to be wrong, which is fine, but it's a great tool. The others you mentioned (beside the NAM)tend to broadbrush precip types in close call situations like this.

[TT-SEA]

00Z runs so far are nothing like the 12Z ECMWF.     It will be interesting to see if it continues the same idea of cold leaking westward over us.

[Kayla]

I was genuinely asking. I was out watching football since earlier this afternoon. 

 

I'm certainly no expert on close calls like this, so I was curious why everyone was so suddenly bullish for snow. 

 

NAM, ECMWF and GEM and now even the GFS are showing higher precip amounts with the GFS saying that there will be a warming slot above freezing around the 800-900mb level. All others say it will stay cold enough to support all snow through the afternoon hours.

[Perturbed Member]

I do trust the WRF a fair amount and use the soundings a lot and usually find them accurate so I'm not too happy to see them looking unfavorable. Still even on the WRF a T-1 inch isn't out of question.

[Deweydog]

NAM, ECMWF and GEM and now even the GFS are showing higher precip amounts with the GFS saying that there will be a warming slot above freezing around the 800-900mb level. All others say it will stay cold enough to support all snow through the afternoon hours.

The NAM is pretty much in agreement with the WRF.

[Perturbed Member]

NAM, ECMWF and GEM and now even the GFS are showing higher precip amounts with the GFS saying that there will be a warming slot above freezing around the 800-900mb level. All others say it will stay cold enough to support all snow through the afternoon hours.

Agree that the main difference is that rapid warning aloft on WRF. Not really sure why the WRF is hell bent on it.

[Kayla]

It generally does pretty well. You may want it to be wrong, which is fine, but it's a great tool. The others you mentioned (beside the NAM)tend to broadbrush precip types in close call situations like this.

 

Don't want it to be wrong, and it is a great tool but just having a hard time believing it at face value, especially looking and comparing current conditions. It's literally been two steps behind at every update. I believe it's best to reference the most recent events to actuality. The WRF-GFS handled our last fake cold episode poorly in late November. Until it proves me wrong, safe to say it will be wrong again and is underestimating the depth and strength of the cold air.

[Kayla]

The NAM is pretty much in agreement with the WRF.

 

NAM seems like it wants to hold onto the cold air a little longer and is more bullish with the precip from what I can see?

[TT-SEA]

Don't want it to be wrong, and it is a great tool but just having a hard time believing it at face value, especially looking and comparing current conditions. It's literally been two steps behind at every update. I believe it's best to reference the most recent events to actuality. The WRF-GFS handled our last fake cold episode poorly in late November. Until it proves me wrong, safe to say it will be wrong again and is underestimating the depth and strength of the cold air.

 

 

Almost a given that the models do not handle the eradication of cold air in this situation.   They will almost always be too fast to warm up in outflow areas.

[Deweydog]

Don't want it to be wrong, and it is a great tool but just having a hard time believing it at face value, especially looking and comparing current conditions. It's literally been two steps behind at every update. I believe it's best to reference the most recent events to actuality. The WRF-GFS handled our last fake cold episode poorly in late November. Until it proves me wrong, safe to say it will be wrong again and is underestimating the depth and strength of the cold air.

The current depth of the cold air isn't the issue. It's currently deep and well-entrenched. What's at issue are the dynamics associated with the warm advection precip. Scouring cold in the mid levels is generally a pretty easy task. The models generally show this to be the case tomorrow.

[BLI snowman]

The NAM is pretty much in agreement with the WRF.

 

Both show 925mb temps going a bit above freezing around 10am. Both a little earlier than the respective operational models. If we're being generous then our window for snow probably extends until noon or shortly thereafter. 

[bainbridgekid]

I drove by Greenlake this afternoon and was surprised how frozen it was.

 

Easily 100+ yards out was iced up near the community center.

[TT-SEA]

I drove by Greenlake this afternoon and was surprised how frozen it was.

 

Easily 100+ yards out was iced up near the community center.

 

 

Green Lake.  

[Kayla]

The current depth of the cold air isn't the issue. It's currently deep and well-entrenched. What's at issue are the dynamics associated with the warm advection precip. Scouring cold in the mid levels is generally a pretty easy task. The models generally show this to be the case tomorrow.

 

I agree with this 100%. So I guess the question of the night is: What model is handling the dynamics of the incoming system best at this time? 

[Deweydog]

I agree with this 100%. So I guess the question of the night is: What model is handling the dynamics of the incoming system best at this time?

There isn't much disagreement, if any.

[bainbridgekid]

Green Lake.  

Thought it looked wrong.

 

You'd think I'd know since I grew up like a mile away. 

 

Anyway, I was pretty surprised to see any ice at all on a lake that size right in Seattle. Guess I wasn't here for the first half of the cold snap though.

[TT-SEA]

Thought it looked wrong.

 

You'd think I'd know since I grew up like a mile away. 

 

Anyway, I was pretty surprised to see any ice at all on a lake that size right in Seattle. Guess I wasn't here for the first half of the cold snap though.

 

 

Its been mostly the last 5 days with the low dewpoints and cold nights.   

 

Before that it was not even going below freezing at night in Seattle.

[Kayla]

There isn't much disagreement, if any.

 

Yet some scurry out the upper level cold air quicker than the others...

[Deweydog]

Yet some scurry out the upper level cold air quicker than the others...

Which models are you referring to?

[Kayla]

Which models are you referring to?

 

00z WRF-GFS specifically.

[Gradient Keeper]

I personally think the WRF and no other model is handling the depth of the cold air correctly. In fact, it is still deepening with Three Corner Rock down to 9 degrees. Mesoanalysis shows -10c at 850mb shifting west towards PDX. For example 4hr RAP trends shows we were around -4c over PDX now we're -6c with -10c over central Gorge shifting west. It's kind of unusual, but the cooler temps in/up over the Gorge verifies this. I really doubt this is moderated tomorrow much at all. The cold layer looks solid surface to 700mb currently. Upper levels will warm 2-4c as the very weak ULL over north-central Oregon continues to drift northwestward. Maybe ZR south of the I-5/I-205 split, but in immediate PDX I am doubting it with east winds still around 4-6 mb continuing to keep the cold layer deep up to 3000' - 4000'. This is my thoughts right now. Then the next question is, do we lose the east winds Monday-Tuesday as the next system approaches. The Cold Pool may not be eroded, so we could re-develop east wind again or see an increase as low pressure is off to the southwest setting the table for possible ZR PDX eastward again, maybe significant.

 

http://www.spc.noaa.gov/exper/mesoanalysis/s11/850mb/850mb_sf.gif?1451799149260

[snow_wizard]

The WRF shows pretty good precip amounts up here early Monday, but gives no indication of any lowland snow.  With easterly winds freezing rain could be a strong possibility for areas of the East Puget Sound lowlands.  I don't mind it so much with rainfall amounts less than a third of an inch or so.  The WRF also indicate many places remaining below 40 for highs on Monday.

[Deweydog]

00z WRF-GFS specifically.

The differences are pretty negligible. We're not talking the difference between nothing and meaningful accumulations.

 

It's a close call, but with the tools available it's a pretty safe bet the precip type will likely be sleet or freezing rain for the majority of this event for the majority of people.

[HighlandExperience]

Hit Mt. Si early this morning, hit the summit at sunrise. It was brutally cold at the top (temps in the teens, with a brisk wind) and had a clear view all the way from Seattle to Tacoma. As TT pointed out early, there was a very thin layer of frozen fog over SE King County where SnowWizard lives and Northern Pierce County. There is about 4-5 feet of hard packed snow at the summit. 

 

http://www.wta.org/site_images/trip-reports/2016/tripreport.image.2016-01-02.5907829029/@@images/fa43f0f8-4132-4a28-931c-3e460773bc27.jpeg

 

http://www.wta.org/site_images/trip-reports/2016/tripreport.image.2016-01-02.5901967072/@@images/ba5e63a0-c815-47a4-b5dc-8a1b036ad435.jpeg

[Kayla]

The differences are pretty negligible. We're not talking the difference between nothing and meaningful accumulations.

 

It's a close call, but with the tools available it's a pretty safe bet the precip type will likely be sleet or freezing rain for the majority of this event for the majority of people.

 

I agree. Either way, looks to be a messy icy day tomorrow and probably an even worse back to work commute Monday morning with below freezing temps continuing.

[BLI snowman]

Operational GFS and NAM do both support snow through 00z Monday (4pm on Sunday). By that point they each show .12-.24" of QPF.

 

MM5 models obviously are several hours quicker with the transition to ice. Would likely be the difference between us getting a quick trace and a quick  widespread 1-2".

 

Will be a nice test for the operationals but all weenieness aside, I think they do have a better handle on it at the moment.

[snow_wizard]

Thought it looked wrong.

 

You'd think I'd know since I grew up like a mile away. 

 

Anyway, I was pretty surprised to see any ice at all on a lake that size right in Seattle. Guess I wasn't here for the first half of the cold snap though.

 

It probably froze so fast because it has been pretty chilly for a couple of weeks now.

[snow_wizard]

Hit Mt. Si early this morning, hit the summit at sunrise. It was brutally cold at the top (temps in the teens, with a brisk wind) and had a clear view all the way from Seattle to Tacoma. As TT pointed out early, there was a very thin layer of frozen fog over SE King County where SnowWizard lives and Northern Pierce County. There is about 4-5 feet of hard packed snow at the summit. 

 

 

 

That's a good snowpack for Mt Si.

[snow_wizard]

The temp continues to drop here with a strong east wind.  Down to 33 with a dew point well below 20.  This goes to show the cold air is quite deep.  I could buy this area not getting snow tomorrow night, but not getting something frozen seems a bit hard to buy. 

[Canadian guy]

http://www.wetterzentrale.de/pics/MT8_Vancouver_Kanada_ens.png

 

Vancouver ensembles improved

[Gradient Keeper]

Definite improvements on 00z GFS Ensembles just after day 6

[HighlandExperience]

I'm happy for you folks down in Portland. I just want to see some snow in Seattle for a change. 

[snow_wizard]

The 0z ensemble shows the operational as a warm outlier.  A lot of cold members for late next week.

 

[snow_wizard]

I'm happy for you folks down in Portland. I just want to see some snow in Seattle for a change. 

 

Let's wait and see what actually happens.

 

Historically Seattle averages about double of Portland so our time will certainly come.

[Deweydog]

I heard recently and repeatedly around here that Mark is all washed up. Pretty suspect forecast. Hope he's right.

[Perturbed Member]

Mark is not going with the WRF or MM5 obviously. His forecast is consistent with what the operational GFS, NAM and ECMWF show. 

[BLI snowman]

Let's wait and see what actually happens.

 

Historically Seattle averages about double of Portland so our time will certainly come.

 

Downtowns average about the same, actually. SEA does get more than PDX, 400' elevation helps.