December 2019 Weather Discussion for the PNW

[Brian_in_Leavenworth]

Nooooo! Hope it stays cool enough over your way to keep the snow around!

If the GFS is right, there will be snow late next week. If the Euro is right, it would rain.

[Jesse]

10-day snowfall per the 00Z Euro. Looks pretty pedestrian for the mountains down here, but the Olympics and North Cascades get absolutely hammered.

 

[Jesse]

If the GFS is right, there will be snow late next week. If the Euro is right, it would rain.

 

Both the GFS and EURO have come around to the idea of another decent rain event possibly following next week's chilly and dry interlude. 

 

We are pretty due for a pineapple express type event, really. I could be mistaken but I don't think we really had a true one either of the last two winters.

[TigerWoodsLibido]

I like you TWL, but there is no way a 12" snowfall was the 2nd best Eugene has ever seen.

Ok...hmm, how about 3-day stretch? 20” in 3 days has to be up there.

[TigerWoodsLibido]

And to TWL, what is your connection to Rutgers, I'm curious.

Fascinated with the mafia and how they’re a large part of the athletic dept boosters. When their football team got good in the mid-2000s, they became my #2 after the Ducks. Hopefully Schiano can get them back into shape.

 

Their basketball team was the 3rd school to send me a jersey.

[Brian_in_Leavenworth]

Both the GFS and EURO have come around to the idea of another decent rain event possibly following next week's chilly and dry interlude.

 

We are pretty due for a pineapple express type event, really. I could be mistaken but I don't think we really had a true one either of the last two winters.

It does look likely for precip next week

Biggest difference is the trough placement. NWS Seattle said that is due to the difference in the ridge over us.

 

"The uncertainty associated with the strength of the ridge is significant".

[MossMan]

Both the GFS and EURO have come around to the idea of another decent rain event possibly following next week's chilly and dry interlude.

 

We are pretty due for a pineapple express type event, really. I could be mistaken but I don't think we really had a true one either of the last two winters.

Did we have one at the very end of December of last year? It rained for nearly 3 straight days non stop and that was when I knew I needed some major new drainage options. But I forgot what the origin of that rain train was from.

[snow_wizard]

Dramatic changes in the European suite of models tonight.  The ECMWF operational, EPS mean, and EPS control all show intense cold developing over AK and a stronger GOA ridge signal in the 10 to 15 day period.  The biggest change is linked to the PV that develops over NW Canada splitting as it drops toward South Central Canada which results in the largest half retrograding toward AK instead of all it dropping into South Central Canada.

 

Looking like a good signal for cold late in the month as I predicted earlier in the month.  The LRC is really in play this season.

 

Some people might think I haven't posted much lately, because I haven't been happy with the current models and recent weather, but that's not the case.

[TigerWoodsLibido]

[Jesse]

[Jesse]

Did we have one at the very end of December of last year? It rained for nearly 3 straight days non stop and that was when I knew I needed some major new drainage options. But I forgot what the origin of that rain train was from.

It might have been a wettish few days up there but I don’t think that qualified as a true, region wide atmospheric river/Pineapple Express. Three days in a row of precip at your location is probably relatively common during the wet season.

[Phil]

Both the GFS and EURO have come around to the idea of another decent rain event possibly following next week's chilly and dry interlude.

 

We are pretty due for a pineapple express type event, really. I could be mistaken but I don't think we really had a true one either of the last two winters.

Lots of model vacillations right now thanks to the battle between the IO-WPAC and the stratospheric instability, but with the +EAMT drawing down AAM input upstream it’s hard for me to see a Pineapple Express (or any “wet pattern”) developing since the jet is now retracting and typically the model trend at this point is towards a more meridional solution as they initialize within the evolving boundary conditions.

[Jesse]

[Phil]

The mid-December period always had potential for more precipitation thanks to the prolonged +EAMT. But it was largely an aberration from the background state, rather than a reflection of a long term change.

 

The remainder of December should be drier than average, though it’s complicated since there is come residual momentum that remains and is not wholly “zonal” but could come into play..would be of a very southerly streamflow in the meridional evolution if it reaches the PNW. But probably brief as well.

[Phil]

However...there IS a change in the background state coming. The +IOD forcing is slowly yielding to what has become a monstrous WPAC warm pool..at some point the WPAC should be the outright dominant tropical exhaust pipe once again.

 

This will likely lead to a highly amplified pattern across the NPAC per the usual (likely a strong -EPO) with Arctic air pouring into the US throughout January, possibly starting late this month thanks to the -AO before the evolution towards -EPO occurs.

[Phil]

Of course, if the WPAC warm pool remains supercharged into the summer, it would make frontal_heatsquall a very happy man even if spring is a washout. But that’s far from guaranteed. Depends on nature of ENSO, the FW, and the rate of descent of the -QBO.

 

Harder to develop -ENSO with -QBO/downwelling easterly shear..much easier to produce a niño with that. But of course, that doesn’t mean it will happen. There are contradictions in the system state.

[Omegaraptor]

even if spring is a washout.

This doesn’t happen anymore.

[Jesse]

[Phil]

This doesn’t happen anymore.

Sarcasm? I don’t know enough about your climate to pick up on these things. But y’all were saying the same thing about niño Februaries last winter, then kaboom.

[El_Nina]

[Omegaraptor]

Sarcasm? I don’t know enough about your climate to pick up on these things. But y’all were saying the same thing about niño Februaries last winter, then kaboom.

Yeah sarcasm. Obviously it can still happen, it’s just that the last 6 or 7 springs have been for the most part torches.

[Phil]

[Phil]

FWIW, I’m pretty sure my +1 prediction for February in the forecast contest will bust warm now. I was very unsure at the time and fell victim to the climo bug. Might be a big mistake if current trends in the tropics/AAM budget continue.

[Phil]

So yeah, winter may end up drier than average, but there is no reason to claim it will be mild. At least not yet.

 

A legitimately colder than average DJF is still on the table for the PNW. December was always likely to be “warm” in my opinion, minus some brief late month potential. I’m not really interested until at least mid-January.

[Phil]

Since misery loves company...pouring rain at 34 degrees here. Truly awful. F**k.

 

This is why I hate WAA with a passion. Screw cold rain.

[ShawniganLake]

Since misery loves company...pouring rain at 34 degrees here. Truly awful. F**k.

 

This is why I hate WAA with a passion. Screw cold rain.

Tim approves this message

[ShawniganLake]

Lots of model vacillations right now thanks to the battle between the IO-WPAC and the stratospheric instability, but with the +EAMT drawing down AAM input upstream it’s hard for me to see a Pineapple Express (or any “wet pattern”) developing since the jet is now retracting and typically the model trend at this point is towards a more meridional solution as they initialize within the evolving boundary conditions.

So toss last nights euro. It was an absolute fire hose for Washington and BC.

[Omegaraptor]

Lots of model vacillations right now thanks to the battle between the IO-WPAC and the stratospheric instability, but with the +EAMT drawing down AAM input upstream it’s hard for me to see a Pineapple Express (or any “wet pattern”) developing since the jet is now retracting and typically the model trend at this point is towards a more meridional solution as they initialize within the evolving boundary conditions.

 

And another thing. GFS ensembles show a brief jet extension between Dec 18 and Dec 22 or so, but after that it goes dry again. Is there a good chance that the dry spell will end up verifying based on what's happening in the atmosphere?

[TacomaWaWx]

We’re up to 1.65” of rain for December. Getting close to surpassing November (1.83”).

[TacomaWaWx]

Looks like it’s not really going to rain much the next 7 days...hopefully things can get wet following this dry stretch.

[Phil]

And another thing. GFS ensembles show a brief jet extension between Dec 18 and Dec 22 or so, but after that it goes dry again. Is there a good chance that the dry spell will end up verifying based on what's happening in the atmosphere?

Well, precipitation doesn’t necessarily mean the jet is “extending” again. There’s some residual momentum though and you might see one more bout of storminess during the week before Christmas, but that might also split/stay offshore. Either way (I think) that’s more of a STJ evolution with southerly flow locally.

[Phil]

So toss last nights euro. It was an absolute fire hose for Washington and BC.

Probably.

[El_Nina]

We’re up to 1.65” of rain for December. Getting close to surpassing November (1.83”).

I don't know if you saw my post but we already passed November's total yesterday. When was your coldest low so far?

[TacomaWaWx]

I don't know if you saw my post but we already passed November's total yesterday. When was your coldest low so far?

yeah I saw that...looked like some nice cells passed through the Willamette valley area yesterday. Coldest low we’ve had so far was 25 on 11/30. I know that a lot of people’s coldest low was in October but it only hit 30 here in late October.

[El_Nina]

yeah I saw that...looked like some nice cells passed through the Willamette valley area yesterday. Coldest low we’ve had so far was 25 on 11/30. I know that a lot of people’s coldest low was in October but it only hit 30 here in late October.

Yep my coldest low is still 22 set back in October as well.

[Brian_in_Leavenworth]

You’re up early.

 

The last three winters have all been pretty decent, no? And wasn’t last summer was the nicest since 2012? Progress!

 

And FWIW I have a colder than average January predicted and still see no reason why February and/or March should be written off. There’s interesting late season potential again thanks to the seasonal cycle during these mixed QBO (descending Erly shear) years. Transition out of strong +IOD in absence of a mid/strong ENSO throws another wrinkle into the mix. Have no analogs for it..only our knowledge on atmospheric dynamics.

 

Those going the “climo” frontloaded route are the ones who will likely get freezerburned.

 

 

I know I should not be looking this far ahead, but what do you think the ENSO will be for next winter?

[TacomaWaWx]

Yep my coldest low is still 22 set back in October as well.

That was a pretty impressive airmass that hit us in late October. Had 3 freezes at the end of the month...which is really hard to do so close to the sound in October. There was also a pretty decent backdoor blast for the gorge and even up here out of the stampede gap.

[ShawniganLake]

Looks like we’re losing momentum on that possible Christmas coldsnap that the GFS was teasing us with

[TacomaWaWx]

10 day rain and snow totals for the 12z. Majority of this falls between days 6-10 so we will see how that works out.

[Brian_in_Leavenworth]

10 day rain and snow totals for the 12z. Majority of this falls between days 6-10 so we will see how that works out.

It has been consistent in moving the trough inland instead of having it retrograde like the Euro.  Of course the Euro has been pretty consistent too so far.