January Weather In the PNW

[TT-SEA]

It has crashed down to 49 at SEA now.

 

50 here with crystal clear skies.

 

Should I go cover the plants in the garden?

[BLI snowman]

This is simply not true. Let's looks at some recent examples.

 

- Nov 2006 was -PNA, huge Pineapple Express in PNW

- Jan 2005 had -PNA while SoCal had a Pineapple Express

- Dec 2010 had -PNA during a major Pineapple express in CA

 

Yes, Pineapple Express systems come via jet extensions...ones all the way from Hawaii.

 

And there certainly hasn't been one this month - but plenty of +PNA for sure.

Yes, Phil is way wrong. Pineapple expresses or atmospheric rivers can stem from very strong southern jet activity, usually brought about by MJO favorability, or from strong baroclinic gradients from the two branches meeting up (which also closely correlates with Arctic airmasses being near the PNW).

 

In the latter case especially, that is not synonymous with +PNA at all and in fact is usually linked with the opposite. Good luck telling Decembers 1955, 1964, or 1996 that they were +PNA. That would be news to them!

[Deweydog]

I don’t know man! It’s crazy!

 

Let’s run a correlation between DJF precipitation and the PNA for the baseline period through which the EOF function is derived from.

 

Positive correlation (albeit very slight)..+PNA has a modest tendency towards increased west coast precipitation.

 

Exactly.

 

Northern California kicks a** precip-wise during +PNA regimes. It's clear as day. Common sense. Right between the eyes.

[Phil]

That's interesting. Good to know what the true definition is based on them creating the index.

Thank you. Finally, someone that appreciates scientific legitimacy. I’m so happy I’m almost in tears.

[Jesse]

That’s fascinating re: glaciers gouging out the Puget Sound trough. The power these ice sheets had is simply amazing to me..how they permanently re-shaped geology in ways that define the landscape even today, and how “quickly”, from a geologic perspective, they were able to do it.

 

The Great Lakes. The Hudson Bay. Long Island. All thanks to frozen water and cold temperatures.

 

The Chesapeake Bay was also formed through seasonal meltwater floods when the rapid warming (4-5C in a few centuries) began following the LGM around 18kyrs ago. It must have been insane during those summers, to have a 20 mile wide, raging torrent of meltwater pouring off the ice sheet from June-August, then having it shut off and turn subarctic again from October - April. Not to mention sea levels rising up to 6”/yr.

 

Yes, then locally for us you have the immense influence of the Bretz or “Missoula” floods. There are still huge glacial boulders scattered throughout the Willamette Valley from those events. The Columbia Gorge was carved out in part from these floods as well. Floodwaters are estimated to have reached 800’ in elevation as water surged across the inland part of the NW and was squeezed through the gap in the Cascades, as the ice dam in present day NW Montana repeatedly failed and reformed.

 

I think the feature you are talking about with regard to Chesapeake Bay is called a “ria”. That is essentially a drowned coastal river valley that was carved out when sea levels were much lower, ie during the last ice age. Gray’s Harbor on the south Washington Coast is a great example of one of those out here.

[Phil]

Exactly.

 

Northern California kicks a** precip-wise during +PNA regimes. It's clear as day. Common sense. Right between the eyes.

Yep. Those ‘roided up Pacific jets that I often describe as “Niño-esque”..well there’s a reason I use that term.

 

All of the top-15 strongest Pacific jets in recorded history occurred in +PNA events.

[Front Ranger]

I mean, what’s so hard about this? You don’t think the CPC adequately researched their own index?

 

So, all of the peer reviewed literature that went into developing the PNA and confirming these statistical facts is somehow completely wrong because of a few pretty drawings and cherry picked years on a map?

 

The CPC's own graphic showed the PNW with below normal precip with +PNA.

 

There was nothing cherry-picked with my map earlier. Here, I'll expand the sample size to include the 7 next highest +PNA Januaries. 

 

 

Are you claiming the maps are wrong?

[TT-SEA]

Yes, then locally for us you have the immense influence of the Bretz or “Missoula” floods. There are still huge glacial boulders scattered throughout the Willamette Valley from those events. The Columbia Gorge was carved out in part from these floods as well. Floodwaters are estimated to have reached 800’ in elevation as water surged across the inland part of the NW and was squeezed through the gap in the Cascades, as the ice dam in present day NW Montana repeatedly failed and reformed.

 

I think the feature you are talking about with regard to Chesapeake Bay is called a “ria”. That is essentially a drowned coastal river valley that was carved out when sea levels were much lower, ie during the last ice age. Gray’s Harbor on the south Washington Coast is a great example of one of those out here.

 

How amazing would it be to watch one of those Missoula flood events from a helicopter.      Its just so hard to comprehend and yet so much of what see today is directly related to what happened repeatedly in those flood events.

[Front Ranger]

Yep. Those ‘roided up Pacific jets that I often describe as “Niño-esque”..well there’s a reason I use that term.

 

It's well documented that CA is wetter on average with Ninos, and the PNW is wetter on average with Ninas, with both regions averaging drier than average when the other one is wetter.

 

This is mainly because it's the northern jet that tend to dominate during Ninas, and the southern jet during Ninos.

[Phil]

The CPC's own graphic showed the PNW with below normal precip with +PNA.

 

There was nothing cherry-picked with my map earlier. Here, I'll expand the sample size to include the 7 next highest +PNA Januaries.

 

cd71.218.95.91.12.20.34.2.prcp.png

 

Are you claiming the maps are wrong?

For f**ks sake man, just run a full correlation through the baseline period covering the EOF function for the PNA loading period.

 

DJF correlation coefficient between PNA/precip, using the same climate division data.

 

Once again, the correlation is (weakly) positive.

 

[Deweydog]

Yep. Those ‘roided up Pacific jets that I often describe as “Niño-esque”..well there’s a reason I use that term.

 

All of the top-15 strongest Pacific jets in recorded history occurred in +PNA events.

I just can't get over it. WHY THE **** WOULD ANYONE ASSOCIATE A +PNA PATTERN WITH DRY WEATHER ON THE WEST COAST??? I FEEL LIKE I'M TAKING CRAZY PILLS!!!

[Front Ranger]

Yes, Phil is way wrong. Pineapple expresses or atmospheric rivers can stem from very strong southern jet activity, usually brought about by MJO favorability, or from strong baroclinic gradients from the two branches meeting up (which also closely correlates with Arctic airmasses being near the PNW).

 

In the latter case especially, that is not synonymous with +PNA at all and in fact is usually linked with the opposite. Good luck telling Decembers 1955, 1964, or 1996 that they were +PNA. That would be news to them!

 

Exactly. Still no answer from Phil on this, as he's held to his claim that +PNA is required for Pineapple Expresses.

 

I'm guessing the answer is that we're both wrong on what is actually a Pineapple Express, along with Wikipedia. 

[Phil]

Yes, Phil is way wrong. Pineapple expresses or atmospheric rivers can stem from very strong southern jet activity, usually brought about by MJO favorability, or from strong baroclinic gradients from the two branches meeting up (which also closely correlates with Arctic airmasses being near the PNW).

 

In the latter case especially, that is not synonymous with +PNA at all and in fact is usually linked with the opposite. Good luck telling Decembers 1955, 1964, or 1996 that they were +PNA. That would be news to them!

The latter instance is not a jet extension.

 

Not only are you woefully wrong regarding the nature of the PNA index as it relates to the jet (both the CPC’s own wordage and data proves me correct), but you’re also mistaken as to how the moisture is delivered into the western United States. The MJO is a trigger for the diabatic heat release process, not the process itself. And it’s one of many triggers.

 

The degree of meteorological ineptitude on this forum is nothing short of astounding. I’m never making another long range prediction on here again. Ever.

[Front Ranger]

The latter case is NOT A JET EXTENSION.

 

Not only are you woefully wrong regarding the nature of the PNA index as it relates to the jet (both the CPC’s own wordage and data proves me correct), but you’re also mistaken as to how the moisture is delivered into the western United States.

 

The degree of meteorological ineptitude on this forum is nothing short of astounding. I’m never making another long range prediction on here again. Ever.

 

No need to be insulting or pouty. Many of us have learned from you, and there are things you can learn from us. 

[Phil]

No need to be insulting or pouty. Many of us have learned from you, and there are things you can learn from us.

The denial of facts needs to stop, dude. The CPC is very clear about this. They created the index..the literature is hyperlinked in the page I linked earlier.

 

The correlation coefficient through the EOF baseline period agrees with me, too.

 

[Jesse]

How amazing would it be to watch one of those Missoula flood events from a helicopter. Its just so hard to comprehend and yet so much of what see today is directly related to what happened repeatedly in those flood events.

We were hiking near Beacon Rock today. Hard to imagine that the floodwaters were nearly as high as the rock itself, if not higher at points. Also amazing to think that this was once the core of an ancient volcano that was exposed as the floods stripped away softer material.

 

[Deweydog]

So Phil... How do think February will play out???

[TT-SEA]

Looks like we have lucked out for MLK Day... dry and warm for everyone with offshore flow.   Earlier runs had rain moving in during the morning.

 

Here is 4 p.m. Monday on the 00Z GFS:

 

 

[Jesse]

Should be progressively cooler down here the next few days as inversions build in the basin and the east wind becomes more of a factor.

[BLI snowman]

The latter instance is not a jet extension.

 

Not only are you woefully wrong regarding the nature of the PNA index as it relates to the jet (both the CPC’s own wordage and data proves me correct), but you’re also mistaken as to how the moisture is delivered into the western United States. The MJO is a trigger for the diabatic heat release process, not the process itself. And it’s one of many triggers.

 

The degree of meteorological ineptitude on this forum is nothing short of astounding. I’m never making another long range prediction on here again. Ever.

I bet you you will.

[TT-SEA]

Should be progressively cooler down here the next few days as inversions build in the basin and the east wind becomes more of a factor.

 

Yeah... ECMWF shows a cool down for the Portland area and more warming here tomorrow as offshore flow kicks.    Advantage up here being that we get downsloping warmth with that east wind.   Andrew's area will also be warmer than the valleys down there tomorrow above the inversion.

 

I was just outside now and there is an east wind starting to stir... feels strangely warm for a clear night in the middle of January.

[Deweydog]

Looks like we have lucked out for MLK Day... dry and warm for everyone with offshore flow. Earlier runs had rain moving in during the morning.

 

Here is 4 p.m. Monday on the 00Z GFS:

 

 

I knew it would come through!

[Phil]

Yes, then locally for us you have the immense influence of the Bretz or “Missoula” floods. There are still huge glacial boulders scattered throughout the Willamette Valley from those events. The Columbia Gorge was carved out in part from these floods as well. Floodwaters are estimated to have reached 800’ in elevation as water surged across the inland part of the NW and was squeezed through the gap in the Cascades, as the ice dam in present day NW Montana repeatedly failed and reformed.

 

I think the feature you are talking about with regard to Chesapeake Bay is called a “ria”. That is essentially a drowned coastal river valley that was carved out when sea levels were much lower, ie during the last ice age. Gray’s Harbor on the south Washington Coast is a great example of one of those out here.

Thank you. That’s fascinating information.

 

Do you know of any good reading material on this phenomena from your region? I honestly could use it right about now.

[Phil]

I bet you you will.

Maybe, I don’t know. I’m burnt out right now.

 

This is definitely the first time in my life that I’ve gotten into a debate over whether or not jet extensions are associated with +PNA. That’s like debating whether 2 + 2 = 4..it’s common knowledge, but believe it or not, it’s actually more difficult to “prove” mathematically than you might think.

[Front Ranger]

The denial of facts needs to stop, dude. The CPC is very clear about this. They created the index..the literature is hyperlinked in the page I linked earlier.

 

The correlation coefficient through the EOF baseline period agrees with me, too.

 

 

That map looks weird. Regardless, it doesn't support your assertion that +PNA = wetter than normal PNW/west coast. Everyone here familiar with west coast weather patterns knows that isn't true.

[TT-SEA]

Awfully nice of those Californians to take another round of rain on Friday and leave us fairly dry and pleasant up here.  

 

[Front Ranger]

Awfully nice of those Californians to take another round of rain on Friday and leave us fairly dry and pleasant up here.  

 

 

 

Suppressed jet!

 

That air mass is notable cooler over the PNW on this run.

[Phil]

That map looks weird. Regardless, it doesn't support your assertion that +PNA = wetter than normal PNW/west coast. Everyone here familiar with west coast weather patterns knows that isn't true.

The problem is that you’re associating +PNA with western ridging, when you should be associating it with North Pacific troughing. That’s the primary anomaly as it relates to the EOF that defines the PNA loading pattern.

 

Guess what? A giant vortex in the NE-Pacific that blasts storms into into the PNW is..you guessed it..a +PNA. Or at least a component of the largest EOF anomaly such that it registers as +PNA.

[BLI snowman]

Maybe, I don’t know. I’m burnt out right now.

 

This is definitely the first time in my life that I’ve gotten into a debate over whether or not jet extensions are associated with +PNA. That’s like debating whether 2 + 2 = 4..it’s common knowledge, but believe it or not, it’s actually more difficult to “prove” mathematically than you might think.

The problem is when you insist on clinging to fairly vague, esoteric terminology like "jet-extensions". An atmospheric river is, by literal definition, a strong extension of the jet. And is not in any way synonymous with a +PNA. And there are plenty of examples if you're curious.

[Front Ranger]

The problem is that you’re associating +PNA with western ridging, when you should be associating it with North Pacific troughing.

 

Guess what? A giant vortex in the Gulf of Alaska that hoses the PNW is, in fact, a +PNA.

 

No, I'm talking purely about the correlations.

 

Of course a +PNA pattern can be wet. Ninos can also be wet in the PNW. But in general, +PNA and +ENSO are both drier for the PNW than -PNA and -ENSO. 

 

Any time there is a ridge over the west coast in winter, that's pretty much always part of a +PNA pattern. If it's a sharp ridge, the interior west may be cooler/wetter than normal. On the other hand, if it's a more east-based +PNA pattern, then the entire West may be warm and the PNW may be wet.

[SilverFallsAndrew]

Possible anafront next weekend?

[MR.SNOWMIZER]

00z is snowy for parts of puget sound

[ShawniganLake]

Phil, you know that our driest and most boring winter patterns occur during positive PNA episodes. Maybe it averages wetter As a weakly positive PNA pattern could lead to a lengthy wet spell. But a big +PNA anomaly is a PNW ridge and a dry one.

[Phil]

The problem is when you insist on clinging to fairly vague, esoteric terminology like "jet-extensions". An atmospheric river is, by literal definition, a strong extension of the jet. And is not in any way synonymous with a +PNA. And there are plenty of examples if you're curious.

See, this isn’t true. The term “jet extension” in subseasonal forecasting only refers to the East Asian-North Pacific jet stream we all know about. It refers to nothing else. There’s nothing vague about that, and it’s very rare to extend this jet without prompting a +PNA/cyclonic response of some kind.

[Phil]

Remember November 2016, and that storm train during the middle of the month?

 

Anyone want to guess what the PNA anomaly was?

 

[ShawniganLake]

Possible anafront next weekend?

Looks like some snow up here. GFS has some heavy accumulation in the south Puget Sound.

[Front Ranger]

00z is snowy for parts of puget sound

 

Lots of potential from day 7 on with this upcoming pattern. There is enough cold air in BC that a low taking the right track could produce a pretty good snowstorm.

[SilverFallsAndrew]

Definitely a lot of potential. Looks like a February/March 2012 like setup.

[Phil]

Phil, you know that our driest and most boring winter patterns occur during positive PNA episodes. Maybe it averages wetter As a weakly positive PNA pattern could lead to a lengthy wet spell. But a big +PNA anomaly is a PNW ridge and a dry one.

Even solid +PNA months like November 2016 can be very stormy/active. That Arctic blast in November 2014 also occurred during a +PNA.

 

This idea that there has to be a ridge over the PNW during a +PNA is a myth. Sure, western ridging is certainly more frequent during +PNA, but it certainly isn’t a certainty or a prerequisite in said regimes.

[ShawniganLake]

Jim’s gonna like the 0z. 522 thickness approaching the border.