October 2019 Weather Discussion for the PNW

[Kayla]

12Z ECMWF shows about an inch of snow for the WA Cascades over the next 10 days... while Kayla gets buried again.

 

Already started skiing on in town trails on Monday!

[Front Ranger]

Would be essentially unprecedented for a wind reversal to occur in early December with the current QBO structure. Not sure we even want that..could promote a stronger mid/late winter vortex.

 

But..it would be one hell of a curveball to open winter. With the sun in a coma and a modoki niño style forcing regime under downwelling easterly shear..who knows what could happen if it gets an early kick.

The truly fascinating thing is that we are observing the sun in a different state than it's been in for over 100 years, but now we have way more tools to measure what's going on throughout the atmosphere and the Earth.

 

I know it's cliche, but I think we might see a lot of "rules" go out the window.

[Phil]

I’ve finally had time to catch up with things today. And unless I’m flat out wrong about everything, I continue to favor the idea of prolific cold into the USA through the first half of winter at least, with a few relaxations, of course.

 

I still favor a major blocking episode in late November, following the mid-month relaxation/jet extension. It is still uncertain whether it will affect the PNW or slide east ahead of a niño-ish December, but either way this isn’t too relevant IMO, as January looks to have the highest potential, should all the pieces align.

 

In the ideal case, the strongest blocking since the last solar minimum begins around New Years. Big cold shot into the country during the first half of the month with an Archambault NAO progression and subsequent EPO retrogression and Arctic intrusion across NW-North America thereafter. Doesn’t have to be this extreme..but this isn’t some far-fetched weenie dream either.

[James Jones]

Good lord, yet another ridiculous cold shot on the Euro. Let's hope it continues to notch a few hundred miles further west...

[Jesse]

Hit 29 this morning, btw. Probably a pretty good shot for PDX to hit 20s tomorrow morning. If the wind dies for me (it blew half the night last night) I could envision mid-20s.

[TT-SEA]

Beautiful day... sunny and pleasant with a light wind.

[Frontal Snowsquall]

Uh oh..here we go again?

 

I remember seeing someone on twitter recently talking about a potential SSW event later this winter. I know it's uncommon but there have been instances of three straight SSW events. If it happens, let it come early. In 1968, the SSW event occurred around Thanksgiving.

[Frontal Snowsquall]

I went to college at Utah State University, which is in the same county that Peter Sinks is in. I was there during the year where that station set a new state record low of -69˚F, in fact. There is a nearby valley called Middle Sink, which is a little less extreme than Peter Sink when it comes to temperature minima, but U.S. 89 travels through that sink. The highway department would close the road when temperatures got below -50˚F; the worry was that if anyone experienced car problems in those conditions, they might freeze to death before they got help.

 

Both Middle and Peter sinks have what is termed an "inverse tree line". With hard frosts every month of the year (temperatures in the teens occur even in midsummer), it's too cold for trees to survive in the bottom of the sinks.

 

That same morning, stations in the bottom of Cache Valley (where the University is) were in the -40's. The campus, being on a bench above the valley bottom, "only" got down to the -15 to -20 range… but was subject to strong outflow winds coming down Logan Canyon. I had a morning class that quarter, and let me tell you -20˚F with 30 mph winds is not pleasant to walk to class in. Using the wind chill charts published at the time, the wind chill factor was literally off the scale that morning! With several feet of snow on the ground, the resulting ground blizzard had conditions looking like something out of a documentary film on the arctic.

 

It's part of the reason I find it hard to consider anything we experience here in the lowlands west of the Cascades to be truly "cold." My benchmark standards for what real cold is got set to a pretty extreme value in my college years!

That makes sense. I couldn't even imagine what those frigid temperatures would feel like.

[Omegaraptor]

I’ve finally had time to catch up with things today. And unless I’m flat out wrong about everything, I continue to favor the idea of prolific cold into the USA through the first half of winter at least, with a few relaxations, of course.

I still favor a major blocking episode in late November, following the mid-month relaxation/jet extension. It is still uncertain whether it will affect the PNW or slide east ahead of a niño-ish December, but either way this isn’t too relevant IMO, as January looks to have the highest potential, should all the pieces align.

In the ideal case, the strongest blocking since the last solar minimum begins around New Years. Big cold shot into the country during the first half of the month with an Archambault NAO progression and subsequent EPO retrogression and Arctic intrusion across NW-North America thereafter. Doesn’t have to be this extreme..but this isn’t some far-fetched weenie dream either.

False. January doesn’t perform anymore and is a spring month now.

 

Except for 1/10/17.

[TigerWoodsLibido]

False. January doesn’t perform anymore and is a spring month now.

 

Except for 1/10/17.

 

Early Jan has been ok.  We had a 7" event down here on Jan 4 that year too.  It's the back half of Jan that hasn't had much of anything since, what, the 70s?

[Phil]

I remember seeing someone on twitter recently talking about a potential SSW event later this winter. I know it's uncommon but there have been instances of three straight SSW events. If it happens, let it come early. In 1968, the SSW event occurred around Thanksgiving.

Later in the winter is favored under the current QBO structure and progression. That’s where I’d look for a significant event, if it were to happen.

 

An early season event would be very bizarre.

[Phil]

Moderate to strong nino, but I don't remember super.

Ah, the one from last winter. Lol. When 2018/19 evolved into a moderate El Niño, I walked back my forecast for 2019/20. I didn’t expect that to happen, so I had to adjust the subsequent year as well.

 

But that was way back in March/April. Didn’t I already explain it? Not sure why it’s relevant now?

[Front Ranger]

Ah, the one from last winter. Lol. When 2018/19 evolved into a moderate El Niño, I walked back my forecast for 2019/20. I didn’t expect that to happen, so I had to adjust the subsequent year as well.

 

But that was way back in March/April. Didn’t I already explain it? Not sure why it’s relevant now?

2018-19 ended up weak Nino.

[seattleweatherguy]

Wow... here we go again. Blocking might just stay in place longer.

 

Snow?

[TigerWoodsLibido]

Snow?

 

In Montana? I would imagine.

[Phil]

2018-19 ended up weak Nino.

The trimonthly ONI reached +1.0C. Semantics, really.

 

Edit: 0.9C. Sorry. Still semantics though.

[Front Ranger]

The trimonthly ONI reached +1.0C. Semantics, really.

It peaked at +.9, per the CPC: https://origin.cpc.ncep.noaa.gov/products/analysis_monitoring/ensostuff/ONI_v5.php

[Phil]

It peaked at +.9, per the CPC: https://origin.cpc.ncep.noaa.gov/products/analysis_monitoring/ensostuff/ONI_v5.php

You beat my edit. Yes, peak trimonthly was +0.9C.

 

Still semantics, since we’re talking 1/10th of a degree. I wasn’t expecting a coherent niño last winter, hence the adjustment I made last spring for 2019/20 (as I said previously).

[MikeInEverett]

Nice day.

[Rubus Leucodermis]

Snow?

 

I am going to feel disappointed if I don't see any snow at my place next month, just because so many signs point to the coming winter being a snowy one, and because there's already a pattern in place of getting cold outflow events.

[Gradient Keeper]

After reviewing 12z runs I notice the GFS flirts with very cold air near far northern Washington and some colder air filters down into the Columbia Basin, but nothing too drastic in terms of changes. The GEM was a bit more blocky and now the EURO, the mighty, the King, has thrown a possible wrench in things saying, "Here, have one more backdoor cold shot!" I notice the energy is held back much further in the Aleutians and if you remember yesterday that was one of the key factors as to how things would evolve in the Day 4-7 time frame which downstream impacts us 1-2 days later. We'll have to see if the EPS offers any support for this and then onto 00z runs! Remember the trend the past 2 months has been for blocking to end up stronger than models project as they keep wanting to break it down and it has been very stubborn to do so. Will that continue? I dunno.

 

 

Last weeks SST Departures:

Niño 4: +1.1ºC

Niño 3.4: +0.8ºC

Niño 3: +0.4ºC

Niño 1+2: -0.2ºC

 

**Latest weekly/This weeks SST Departures:

Niño 4: +1.0ºC

Niño 3.4: +0.6ºC

Niño 3: +0.1ºC

Niño 1+2: -1.3ºC

 

18z GFS in 1 hour 3 minutes

[Gradient Keeper]

Hmmm! 12z GFS Analog Composite

Day 6-10. Almost a 95% score and check out those cold years popping up! Look at that tilt!

 

 

[TT-SEA]

FWIW... the 12Z EPS is quite a bit farther east with the cold air next week compared to the operational run.

 

It also shows a warmer and wetter pattern developing by the end of the run.  

[Gradient Keeper]

12z EPS Day 5-8 looks like the blocking signal is stronger than past 2 runs and although it doesn't drop over us the cold air/arctic trough is considerably further west.

 

00z GFS in 6 hours 52 minutes

[Frontal Snowsquall]

False. January doesn’t perform anymore and is a spring month now.

 

Except for 1/10/17.

Early January 2004 was pretty good. Just wish there was more snow and less ice.

[ShawniganLake]

Early January 2004 was pretty good. Just wish there was more snow and less ice.

There have been lots of okay January events and close calls in recent years around the PNW. Just no big regional arctic airmasses.

2005

2007

2011

2012

2017

[Requiem]

False. January doesn’t perform anymore and is a spring month now.

 

Except for 1/10/17.

 

2017 was awesome. I mean, how often in the PACNW lowlands does one get 4 inch snowfall rates, thundersnow, high winds, and 12+ inches of snow in a single event? I got nearly 20 inches out of that event. and an ice storm right before it.

[High Desert Mat?]

The last one is from Christmas’14. The rest are just scattered throughout cold snaps through the years. The first one is my daughter this morning getting ready for pj day at school.

[High Desert Mat?]

Not sure why the top one is sideways and the rest are good. Hmmm

[Phil]

FWIW... the 12Z EPS is quite a bit farther east with the cold air next week compared to the operational run.

 

It also shows a warmer and wetter pattern developing by the end of the run.

Should be noted that the EPS does have a bias to over-blow WPAC/dateline convection in the extended range, which at this time of year would favor more eastern cold.

 

With the building MJO and warmth in WPAC, that type of pattern is likely at some point, but it’s also something the EPS seems to revert to quite frequently.

[Gradient Keeper]

Should be noted that the EPS does have a bias to over-blow WPAC/dateline convection in the extended range, which at this time of year would favor more eastern cold.

 

With the building MJO and warmth in WPAC, that type of pattern is likely at some point, but it’s also something the EPS seems to revert to quite frequently.

What's your gut feeling? Renewed blocking/cold pattern west, or pattern change after Day 8-9, block breaks down, wetter pattern.

 

00z ECMWF in 8 hours 25 minutes

[Phil]

What's your gut feeling? Renewed blocking/cold pattern west, or pattern change after Day 8-9, block breaks down, wetter pattern.

 

00z ECMWF in 8 hours 25 minutes

The latter. These jet extensions can be rushed by guidance, and this one might be more of the STJ variety affecting southern areas, but it’s coming. Will be brief though..lasts 10 days before the next -EAMT/retraction cycle, which brings on the next round of blocking.

[Gradient Keeper]

The latter. These jet extensions can be rushed by guidance, and this one might be more of the STJ variety affecting southern areas, but it’s coming. Will be brief though..lasts 10 days before the next -EAMT/retraction cycle, which brings on the next round of blocking.

Yeah I'm thinking since Climo favors it we'll see something similar wetter pattern 10-14 days, then the blocking pattern resets.

 

6z GFS in 11 hours 5 minutes

[SilverFallsAndrew]

18z has some cold air bleeding in east of the Cascades in the mid-range. 

[Gradient Keeper]

Well, well, well..... GFS trending towards the colder EURO?

 

 

[MossMan]

Well, well, well..... GFS trending towards the colder EURO?

 

 

Just a few notches and tweaks and we are in business!

[Gradient Keeper]

Just a few notches and tweaks and we are in business!

Yep. C'MON!!!!

[GobBluth]

 

this could be interesting

[wx_statman]

Possible state record low set in Nebraska this morning as well (for October), with a -16 reading at Harrison 9NE. Listed state record for the month is -15 in 1925. 

[Gradient Keeper]

 

this could be interesting

I saw that as well. 18z was very Drunk Uncle-ish, or WAS IT? ...

 

00z GFS in 4 hours 15 minutes