December Weather In the PNW

[HighlandExperience]

I’ll stick with the euro

[MR.SNOWMIZER]

The nam is defecating on us.

[Jbolin]

This is going to be an all rain event below 1000 ft

 

BOOK IT!

[Jesse]

Borderline setup continues to be borderline.

Borrow Matt’s hanglider for the day?

[MossMan]

FB post from NWS Seattle just a bit ago.

[SilverFallsAndrew]

NAM also starts precip during the warmest part of the day tomorrow.

[HighlandExperience]

Seems like Seattle nws discounting euro ok

[SilverFallsAndrew]

[snow_wizard]

12z NAM ends up alright in the end... Shows the changeover to snow overnight and then continues snow into the early afternoon for Northern King/Snohomish/Skagit counties.

 

Almost has a resemblance of a convergence zone. If we could get one of those on Monday behind the low that might work out really well for some places.

 

Yup...behind the low is when we will shine.  I still pick King County for the best action from that.

[snow_wizard]

This is going to be an all rain event below 1000 ft

 

BOOK IT!

 

It won't.  At least in the Seattle area.

[MR.SNOWMIZER]

Yup...behind the low is when we will shine.  I still pick King County for the best action from that.

Yep, i will do fine with overrunning and you will behind the low.

[TT-SEA]

Why bet against the ECMWF details within 48 hours?

 

It does not show any rain north of Kelso.  

[snow_wizard]

Yikes.

 

It's the NAM.  I have no idea why people even bother with this model.  It is terrible most of the time.  That having been said it will get colder after the low passes and there will probably be convergence.

[Geos]

Seems like Seattle nws discounting euro ok

 

Yeah it kinda does. I wouldn't mind a northern jog in the EURO, because it does keep it colder.

 

With the NAM on the other hand, I think it is too far north.

[snow_wizard]

Right now if you average out the tracks of the various models Seattle looks like a good place to be.

[Geos]

Yup...behind the low is when we will shine.  I still pick King County for the best action from that.

 

I think if you were to blend all the snowfall maps the heaviest amounts would show in King County somewhere. 

 

To me, it smells like snow in the air! 

[snow_wizard]

No offense Jim, you are very knowledgeable  and thorough but I have lived here for 35 years and I have seen systems similar to tomorrow's come in further south and produce rain for the KSEA area as a warm nose pushes in ahead of or along with the main precip band. 

 

Yes we have some decent offshore flow in areas and DP's are near freezing or below, I'm not happy with the eventual low placement pegged by the NAM (as it usually is correct) in these marginal situations

 

Despite what the ECMWF, GEM and NAM are showing and with marginal 925's I've seen this type of setup lead to disappointment numerous times ( tomorrows low looks very weak) and I'm just not buying it this time. If we had much coder air over the "crest" and even colder air to the north I'd be a bit more optimistic. 

 

 

 

Every model (including the NAM) shows good CAA in the late evening and then some kind of convergence through 12z or so.  My experience with these situations is the models almost always cut off precip too quickly.  I'm willing to keep and an open mind and I hope you will do the same.

[andrewr]

Not sure if this has already been posted, but just in case it hasn't... http://komonews.com/weather/scotts-weather-blog/longtime-national-weather-service-employee-in-seattle-ted-buehner-to-retire-after-40-years

[MossMan]

Still only 31 here at 1:30pm!

[Geos]

RGEM sure gets it cold tonight.

 

[FroYoBro]

12z ECMWF ensemble members show many of the lows heading south of PDX. Based on this and the fact models have a hard time factoring in a snow covered Columbia River Basin, I'm going to go with my gut on this one and go for a white Christmas for PDX Metro. A widespread 3 to 6 inches of snow, followed by sleet then freezing rain.

Good luck with that. The upper/mid levels are going to be too warm. 

[snow_wizard]

I think if you were to blend all the snowfall maps the heaviest amounts would show in King County somewhere. 

 

To me, it smells like snow in the air! 

 

I agree.  These post low situations almost always favor King County with the low track being shown.  I'm getting some seepage from the pass here now and the air mass has dried out quite a bit.  That will really help us with the overrunning part of the event, but that is shaky IMO.

[Front Ranger]

You seem pretty confident about low elevation snow from roughly Olympia north.

 

Given your usual knack for pessimism, that makes me optimistic.

On the other hand, Tim was confident yesterday that the storm was going south...

[Frontal Snowsquall]

For PDX 12z ECMWF shows light snow arriving just after sunrise. Then just after 12pm, it shows warm tongue coming and changing parts of PDX Metro to ice but then just before sunset heavier moisture comes and also low swings by to the south and most of the area changes back to moderate snow. Then back to ice as we call it a night. Tomorrow is going to be fun tracking this winter storm.

[MossMan]

Not sure if this has already been posted, but just in case it hasn't... http://komonews.com/weather/scotts-weather-blog/longtime-national-weather-service-employee-in-seattle-ted-buehner-to-retire-after-40-years

One of the greats at NWS Seattle! He’s been there as long as I have been alive.

[TT-SEA]

On the other hand, Tim was confident yesterday that the storm was going south...

12Z ECMWF was way south... farther south then when I made that statement.

[Perturbed Member]

It's the NAM.  I have no idea why people even bother with this model.  It is terrible most of the time.  That having been said it will get colder after the low passes and there will probably be convergence.

 

 

It honestly did ok last winter, but I would agree that the 18z NAM looks pretty suspect. 

 

I'd feel pretty good about at least some snow in SEA right now. 

[snow_wizard]

GFS is slightly slower than previous runs with the low center coming in around Raymond.  Surface maps show a less extensive rain area than previous runs in the Puget Sound region during the warmest part of the event.

[Jbolin]

One of the greats at NWS Seattle! He’s been there as long as I have been alive.

Ted Buehner has been there for some notable events. 

 

Hanukkah Eve Windstorm

Inauguration Day Storm

1997 Tornado Outbreak

1996 Major snow event (right after Xmas)

1996 Major flooding event 

1989 Snowstorm 

etc. etc.

[westcoastexpat]

I have to agree with Jim. King County and surrounding favourable areas have a reasonable chance at 3" or so.

[Perturbed Member]

For PDX 12z ECMWF shows light snow arriving just after sunrise. Then just after 12pm, it shows warm tongue coming and changing parts of PDX Metro to ice but then just before sunset heavier moisture comes and also low swings by to the south and most of the area changes back to moderate snow. Then back to ice as we call it a night. Tomorrow is going to be fun tracking this winter storm.

 

Euro is pretty much on its own for PDX snow, pretty much all of the other models except maybe the WRF shaft us and I will discount the WRF because I don't see how its modeled track can produce what its snow map shows, we only briefly have a snow profile on the soundings and the precip at the time is quite light. 

It is interesting that the euro has been sticking to its guns by staying noticeably further south than the other models but my gut feeling is that this is a SW WA and north event. The euro was wrong about shifting things south for the event last February, it can be wrong again. 

 

I'd go with 0-1 inch for PDX and some spotty ZR. Might have more of an issue with freezing rain on the east metro. 

[snow_wizard]

The GFS still shows King County doing very well.  My area has been shown to be right on the line for the heavier totals for 4 runs now.

[MR.SNOWMIZER]

1990 arctic express and november 85 also.

[Deweydog]

Borrow Matt’s hanglider for the day?

You never stopped by on your way back down this morning. We didn't leave for the beach until 8:30 or so...

[Front Ranger]

12Z ECMWF was way south... farther south then when I made that statement.

No definite trend south in the models, though. None at all really since yesterday.

[MossMan]

Going to be a cold night! Still at 31.

[SilverFallsAndrew]

Well I could see next week being below average overall with some inversiony days...

[snow_wizard]

It just dawned on me that the ECMWF shifted a bit north, which is somewhat likely, would be awesome for Seattle.  

 

The 18z GFS still looks good with decent amounts of precip happening after the CAA has commenced.

[snow_wizard]

Ted Buehner has been there for amazing notable amazing events. 

 

Hanukkah Eve Windstorm

Inauguration Day Storm

1997 Tornado Outbreak

1996 Major snow event (right after Xmas)

1996 Major flooding event 

1989 Snowstorm 

etc. etc.

 

His first really good event would have been the January 1980 snowstorm.

[Frontal Snowsquall]

Euro is pretty much on its own for PDX snow, pretty much all of the other models except maybe the WRF shaft us and I will discount the WRF because I don't see how its modeled track can produce what its snow map shows, we only briefly have a snow profile on the soundings and the precip at the time is quite light. 

It is interesting that the euro has been sticking to its guns by staying noticeably further south than the other models but my gut feeling is that this is a SW WA and north event. The euro was wrong about shifting things south for the event last February, it can be wrong again. 

 

I'd go with 0-1 inch for PDX and some spotty ZR. Might have more of an issue with freezing rain on the east metro.

 

Yeah I can definitely see where you're coming from. I'm glad the event is almost here and we will find out what will happen. It's been wild model riding this event.