November 2019 Weather Discussion for the PNW

[Gradient Keeper]

This tells us how much garbage the GFS Op run is Day 3-6 when there are such dramatic changes between it and its ensembles.

[Gradient Keeper]

The 00z GEFS looks much improved to me..

 

Sharper wavetrain upstream..can see the loading pattern for the next -EPO over the NW-Pacific. And still plenty of cool air in the West with a -NAO holding it in place while we wait for the EPO.

Yeah long range pattern looks pretty dang good.

 

[Phil]

With 1.51" now on the month, SEA has successfully passed both 1976 and 1952 in wetness. 1956 will fall this weekend, and then if 1979's 1.94" can be surpassed, they'll be safely into good analog territory.

 

Of course, as has been discussed, if you go further back past the airport era, several of the driest Novembers preceded excellent winters: 1936, 1929, 1922.

I found a correlation coefficient of ~ 0.1 (essentially zero) between S/O/N precip departures and D/J/F temps @ SEA since the 1960s, so it’s hard to claim there’s a statistically significant relationship that cannot be explained by ENSO et al.

 

But it’s safe to say the dry fall will probably verify in most areas (always a few isolated exceptions). Last 60 days:

 

[Perturbed Member]

Yeah, same here. I remember walking to school that morning in a cold, heavy rain. By the middle of first period there were big fat flakes mixed in. By the end it was sticking.

 

Any information about what setup produced that event? I remember the event but didn't start really reading weather maps and models until the Jan 2004 snow.

[Phil]

Precipitation anomalies this month are pretty outrageous:

 

[Front Ranger]

I found a correlation coefficient of ~ 0.1 (essentially zero) between S/O/N precip departures and D/J/F temps @ SEA since the 1960s, so it’s hard to claim there’s a statistically significant relationship that cannot be explained by ENSO et al.

 

But it’s safe to say the dry fall will probably verify in most areas (always a few isolated exceptions). Last 60 days:

 

 

Yeah, SON will definitely end up dry for the southern half of the PNW. Will be a lot closer to normal for areas further north, but overall dry looks like a good call.

[snow_wizard]

Really nice GFS run tonight.  Like some of the earlier Euro runs it all stems from stronger positive anoms off the coast fairly early in the game.  We shall see how it all plays out.

[Gradient Keeper]

00z GFS Ensembles

Portland, Seattle, Yakima

 

Strong agreement for a pattern change to wet, cooler, possibly active, and feet upon feet of Mt. Snow! Seeing some chillier members sneaking south of that -5c line. Yakima ensembles indicates there is some potential for backdoor cold air.

 

 

Portland
http://old.wetterzentrale.de/pics/MT8_Portland_Oregon_USA_ens.png

 

 

Seattle

http://old.wetterzentrale.de/pics/MT8_Seattle_USA_ens.png

 

 

Yakima

http://old.wetterzentrale.de/pics/MT8_Yakima_USA_ens.png

[Front Ranger]

You also gotta remember that November is statistically the wettest month of the year for WA, so a very dry November will weigh heavily on overall fall precip.

[Phil]

[snow_wizard]

Unfortunately the GEFS says, NOPE! ...Day 5-6 is nowhere remotely close to the Operational run. Darn.... Dang

 

It's not terrible either.  The mean is pretty chilly Nov 25 through Dec 5 now.  The GEM looks decent also.  It also appears the prospects for a fairly strong unusually far south tracking low could also be in the cards the middle of next week.  

[snow_wizard]

You also gotta remember that November is statistically the wettest month of the year for WA, so a very dry November will weigh heavily on overall fall precip.

 

I think it will always be a battle between Nov and Dec for wettest month.

[TigerWoodsLibido]

 

Much better!!

[snow_wizard]

Man...that GFS is really good.  Northerly gradients with sub 522 thickness for a time next week.  Easy -10 daily departures if that verifies.

[Front Ranger]

[TigerWoodsLibido]

[Front Ranger]

I think it will always be a battle between Nov and Dec for wettest month.

 

Yeah, it depends on period of record. For the airport era, November has been a bit wetter from about OLM north. But prior to that December was about equal or a little wetter.

[El_Nina]

Man I wish it would dry out already.

[Phil]

It hasn't even really been a ridgy fall for the PNW (just for much of this month), as the region has been in between the dominant block in Alaska and mean trough over the northern Rockies/Plains.

 

Big difference from years like 1976 and 1952, where the fall pattern featured a big fat ridge right over the PNW.

 

comphour.kFH9wo5idc.gif

 

comphour.5EYxvTleTh.gif

 

comphour.VH7fzTrbjJ.gif

We’re certainly in a different climate ere now, so the circulations and wavetrains will behave differently through seasonality and similar external forcings. Which is why caution should be used before relying on older analogs from decades that may not be, well, “analogous” to the present era.

[Phil]

But there are elements conveyed through some of those older analogs such as 1976/77, etc, that can be utilized to predict aspects of the evolution of the current system state, even if not verbatim. More recent analogs make it easier and would be weighted more heavily vs the older ones, of course.

[kokaneekidz]

I just have a hunch we will see snow accumulate below the 500' level within the next week. This is a first step in the right direction.

[snow_wizard]

It hasn't even really been a ridgy fall for the PNW (just for much of this month), as the region has been in between the dominant block in Alaska and mean trough over the northern Rockies/Plains.

 

Big difference from years like 1976 and 1952, where the fall pattern featured a big fat ridge right over the PNW.

 

comphour.kFH9wo5idc.gif

 

comphour.5EYxvTleTh.gif

 

comphour.VH7fzTrbjJ.gif

 

No doubt the block position has been worlds better this year than 1976 and 1952.

[Deweydog]

1949-50.

[SilverFallsAndrew]

Pretty big improvement on the GFS ensembles. 

[Front Ranger]

I could be wrong, but isn't the GEFS still run off the old GFS? I thought I heard that the new GFS hasn't been incorporated into the ensembles yet. That could possibly explain some of the differences in the mid range we've seen.

[snow_wizard]

The WRF shows some really impressive north winds setting in over WA and the northern half of OR with that low next week.  Would love to see that verify.

[snow_wizard]

I could be wrong, but isn't the GEFS still run off the old GFS? I thought I heard that the new GFS hasn't been incorporated into the ensembles yet. That could possibly explain some of the differences in the mid range we've seen.

 

That is pretty interesting if true.

[BLI snowman]

December 10, 1919

[Front Ranger]

That is pretty interesting if true.

 

Just double checked and it appears so.

 

I'm seeing reports that the GEFS won't be upgraded to the FV3 (new GFS) core until sometime next year.

[Requiem]

The WRF shows some really impressive north winds setting in over WA and the northern half of OR with that low next week.  Would love to see that verify.

 

Yeah, for sure. Comes straight south of the metro area and actually tightens the gradient quite a bit.

[snow_wizard]

December 10, 1919

 

 

[Deweydog]

January 6, 1743.

[snow_wizard]

Some really nice analogs in the mix based on the 0z GFS.  Heavy hitters like Nov 1955 and Dec 1972 continue to make a showing.

[GHweatherChris]

11/20 in just 1 hour 46 minutes, boom!!

[luvssnow_spokane]

December 23, 2022

[snow_wizard]

January 6, 1743.

 

OMG!  That made 1862 look tropical.

[Gradient Keeper]

00z ECMWF Day 4

 

[snow_wizard]

00z ECMWF Day 4

 

 

Classic setup for an explosive 150 ridge.  Anomaly intensity of that flat offshore ridge is the biggy right now.

[TigerWoodsLibido]

Something brewing...

[Gradient Keeper]

Day 5