December Weather In the PNW

[Gradient Keeper]

Good night all. 6z GFS in 2 hours 23 minutes, 12z GFS in 8 hours 23 minutes

[Phil]

PNW weather week to week? That's not what you said before, we were strictly talking about NAO/PNA relationship.

Not my fault you can't read sometimes. I said the relationship is (statistically) a long term/low frequency phenomenon, however that doesn't mean there isn't constructive feedback on shorter intervals as well.

 

It really depends on the nature of the macro scale boundary state(s) and forcings on the waveguide, something you'd probably appreciate more if you researched climate dynamics for an academic career, rather than as a hobbyist.

[Phil]

BTW, this Euro run won't verify.

[seattleweatherguy]

I'm happy to wait until Jan if it can be cold or even better historic.

[wx_statman]

Was there no legitimate warmth that month?

 

There was. Those Salem readings are next to impossible however. The peak of the warmth didn't even happen regionally until the 13th, when Medford hit 71 and Baker City a late-season record of 59. 

[VancouverIslandSouth]

Day 10 not yet, but I am liking where the pattern is going for sure.

http://maps1.pivotalweather.com/maps/models/ecmwf/2017120700/240/500h_anom.na.png

 

Now that's the sort of pattern I'm looking for.

[VancouverIslandSouth]

Inversion has strengthened this evening. 31F at home. 500ft up the hill it’s 42F.

 

A lot more mixing going in this area. It's currently 41F here and actually warmer at the bottom of the hill.

[snow_wizard]

 

Day 9 ohhhh Kona Low CHECK. Flat Pacific ridge CHECK. hmmm

 

 

Nobody can say that isn't a Kona low!  I think we have a reasonable chance of scoring before the month is over.

[snow_wizard]

Now that's the sort of pattern I'm looking for.

 

That is a good one, but we can get retrogressions of full latitude ridges also.

[snow_wizard]

BTW, this Euro run won't verify.

 

Maybe not, but the models are starting to get interesting now.

[snow_wizard]

The temp has plunged to 33 after sitting at 52 when I got home 6:00pm.  No doubt the surface gradient has become more ESE instead of ENE which means strong inversions coming.

[Phil]

Maybe not, but the models are starting to get interesting now.

I think the models have been "interesting" for weeks now. At least in terms of the processes and progressions that should eventually lead to an Arctic blast in the western US.

 

The precursory signs in the waveguide and tropics have been present since the middle of November.

[HighlandExperience]

Nobody can say that isn't a Kona low! I think we have a reasonable chance of scoring before the month is over.

Phil has no faith

[Jesse]

There was. Those Salem readings are next to impossible however. The peak of the warmth didn't even happen regionally until the 13th, when Medford hit 71 and Baker City a late-season record of 59.

Yeah, I’m aware the Salem readings were largely debunked. I was still under the impression that the month featured some actual downslope driven warmth west of the Cascades, though.

[Jesse]

Perhaps so, but how is that relevant to what I posted?

It sounded like you don’t think we will see a -PNA again until the end of the month. I suppose that doesn’t necessarily mean you think we will be under a ridge between now and then, but you have said things in the last few weeks that appear to insinuate just that.

[Phil]

It sounded like you don’t think we will see a -PNA again until the end of the month. I suppose that doesn’t necessarily mean you think we will be under a ridge between now and then, but you have said things in the last few weeks that appear to insinuate just that.

I don't see any longwave troughing in the west until after Christmas. That doesn't mean you'll be sitting under a giant ridge the entire time, obviously, but it still looks (generally) ridgy to me until the very end of December.

[wx_statman]

Yeah, I’m aware the Salem readings were largely debunked. I was still under the impression that the month featured some actual downslope driven warmth west of the Cascades, though.

 

Oh, ok. I just wasn't clear what you meant by your initial response then. It was ambiguous. 

 

December 1929 did feature plenty of actual warmth, but there weren't any notable dry stretches. I imagine most of the warmth was fueled by SW winds, including on the 13th. Salem recorded 2.36" the following day.

[ShawniganLake]

EPS looks a lot like the operational at day 10. Ridge rebuilds days 12-15 but is too close to the coast.

[snow_wizard]

EPS looks a lot like the operational at day 10. Ridge rebuilds days 12-15 but is too close to the coast.

 

The control looks pretty similar also.  I do see a theme of a ridge rebuilding close to the coast again, but it looks poised for a quick retrogression as above normal heights approach from Siberia.

[snow_wizard]

Out of all the years I've lived here I've never seen it get foggy 5 hours after an east wind stops blowing...until now.  I've never even seen it get foggy in the same night that started out with an east wind.

[ShawniganLake]

Getting closer

 

[WeatherArchive]

What would our weather be like if we weren't polluting the atmosphere up to death?  Do you think we might be colder with more snow or do you think perhaps our pollution actually keeps the insane heat more in check?

[Deweydog]

20's!!!

 

#thanksKonalow!

[SilverFallsAndrew]

29 Salem

28 IMBY

24 Corvallis

24 Eugene

[Geos]

Down to 30 with heavy frost again this morning. Surprised there hasn't been more fog this week under this inversion. One of the nicest inversions I've experienced!

[MossMan]

Clear and 29 degrees. Heavy frost.

[Jesse]

The wind was raging here when I went to bed last night, but it is now calm and the temp has plummeted to 30 over the last hour.

 

Looks like PDX and TTD are still holding onto easterlies. Good sign we are transitioning to a gap wind as opposed to a downslope situation.

[MR.SNOWMIZER]

Fog

[TT-SEA]

Down to 30 with heavy frost again this morning. Surprised there hasn't been more fog this week under this inversion. One of the nicest inversions I've experienced!

 

47 and bone dry here with the east wind.     Lip chapping dry out there.  

[Timmy]

This mornin is much more inversiony here

[Gradient Keeper]

The wind was raging here when I went to bed last night, but it is now calm and the temp has plummeted to 30 over the last hour.

 

Looks like PDX and TTD are still holding onto easterlies. Good sign we are transitioning to a gap wind as opposed to a downslope situation.

As of 7 AM PDX-DLS -11.6mb, nearly 3mb stronger than modeled. The strongest east winds for those east of I-205/western Gorge are yet to come.

 

Columbia Basin cold pool update

925mb Analysis

 

Cold pool very evident looking at latest upper air analysis with temps cooling to -2c. Under this air mass I see temps are in the low to upper 20s and that low clouds/ice fog has developed. This will persist for the coming many days. We've been expecting this. However, in terms of cold pools this one is marginal as often in December-early February during a modified arctic air mass it can be as cold as -10c to -15c. Nonetheless, it has progressively cooled off some areas east of I-205. A perfect example is I am now at 39.5 compared to 44.3 24 hours ago. Corbett is also down 5 degrees. Wind sheltered areas are well down into the mid to upper 20's which was expected with the dry air and clear skies. This is typically what a cold pool does it over time as it persists and tends to cool further the east winds draw in colder air dropping temps. We may see this continue the next several days with high temps a bit cooler 40-44 east of I-205.

 

[Gradient Keeper]

12z GFS

 

Day 5

http://maps1.pivotalweather.com/maps/models/gfs/2017120712/120/500h_anom.na.png

[Geos]

12z GFS

 

Day 5

 

 

The ridge looks like a heart!

 

Crazy seeing 582 up to the Columbia like that.

[Gradient Keeper]

Day 6

http://maps1.pivotalweather.com/maps/models/gfs/2017120712/144/500h_anom.na.png

[Timmy]

The ridge looks like a heart!

 

Crazy seeing 582 up to the Columbia like that.

Thinking about planting some veggies in the garden.

[umadbro]

Beautiful spring morning! Mid 40's, wall to wall sunshine! We deserve this after that epic winter we just had!

[Gradient Keeper]

Day 7 Meh

http://maps1.pivotalweather.com/maps/models/gfs/2017120712/168/500h_anom.na.png

[SilverFallsAndrew]

Currently 22 @ EUG.

[umadbro]

Day 7 Meh

http://maps1.pivotalweather.com/maps/models/gfs/2017120712/168/500h_anom.na.png

Dat Greenland block tho...

[SilverFallsAndrew]

Day 7 Meh

http://maps1.pivotalweather.com/maps/models/gfs/2017120712/168/500h_anom.na.png

 

Were you expecting the short/medium term to suddenly change?