October 2016 Observations and Model Discussion for the Pacific Northwest

[Front Ranger]

Come on, Jared. You can't call yourself educated in this field unless you have a Ph.D. and years of research experience.

I didn't call myself well educated on it. I also didn't tell other people in the discussion to educate themselves before forming an opinion. That's insulting and wrong.

 

The funny thing is, you don't have to have a Ph.D to understand the basics. And you only need to know the basics to understand that claiming "warmer source region = warmer air masses" is a flawed and overly simplistic argument.

[wx_statman]

As they say...you see what you want to see.

 

Stick to the actual discussion. Calling each other contrarian, which I could easily do as well, is not productive.

 

As if that's not what I was doing.

 

I think we're done here. 

[Phil]

Statistically speaking, the only variable featuring a *statistically significant* correlation w/ the wintertime AO/NAO (NAM) is solar forcing. While there are a number of conduits through which these effects may take place, most of them involve the upper atmosphere, particularly the stratosphere, as a communicator of sorts. There's some great literature on this topic, for what it's worth, as well as some fascinating correlations so strong they're undeniable. Yet, in many cases we remain in the dark as to the physical nature of these correlations.

 

These are a few of a favorite papers:

 

http://onlinelibrary.wiley.com/doi/10.1002/jgrd.50374/full

 

http://onlinelibrary.wiley.com/doi/10.1002/jgrd.50236/full

 

http://www.sciencedirect.com/science/article/pii/S0273117713005802

 

http://www.sciencedirect.com/science/article/pii/S1364682604001798

 

http://www.sciencedirect.com/science/article/pii/S1364682616300360

[Front Ranger]

I'm just wondering two things: 1) how it works, and 2) why has it mainly just affected mid winter? Why have we seen an increase in early season cold blasts, when the Arctic warm anomalies have in fact been warmest in the fall?

 

 

Nobody has made that claim. Rather, a warmer Arctic has been sited as one of the contributing factors. And why wouldn't it be? Warmer source airmass = warmer result at lower latitudes. 

 

 

The idea that the relatively tiny Arctic domain is the "source" for most/all of the cold air over the Northern Hemisphere is logically flawed. Physically speaking, the "source" is actually the upper troposphere and lower stratosphere above 40N.

 

Getting back to the main discussion...I think these three posts really sum up the crux of the issue.

[wx_statman]

Getting back to the main discussion...I think these three posts really sum up the crux of the issue.

 

A warmer source airmass = warmer result at lower latitudes. 

[Front Ranger]

A warmer source airmass = warmer result at lower latitudes. 

 

So simple.

 

You disagree with Phil on this. Why is he wrong?

[Phil]

A warmer source airmass = warmer result at lower latitudes.

Well, I think it's more complicated than that.

 

Put simply, the deepest, most frigid polar airmasses technically arise aloft, within the polar vortex itself, in its lower/middle levels, poleward of 40-45N. The airmass within the polar vortex cools exponentially as O^3 and N^2O are molecularly dissociated under the dearth of solar radiation (which photochemically maintains production). Sometimes temperatures in the PV can plunge to levels as low as -100C.

 

The mobile polar high production associated with the strongest Arctic blasts over the middle latitudes arises when and planetary wave fluxes/related resonances disrupt the vortex, which is both kinetically and thermally coupled to the troposphere via diffusive and radiative processes. The stratospheric warming occurs as air sinks and pressures rise, hence adiabatically warming to levels as high as 50C. When the wave cycle completes, the airmass radiatively cools and dominant photochemical processes resume, which naturally leads to further pressure rises, etc. This process is occurring constantly even in years with strong PVs/+AOs.

[Phil]

The polar stratosphere and upper troposphere haven't warmed at all during the satellite era. In fact, polar temperatures above 300mb have cooled slightly. The arctic surface temperatures aren't exactly relevant given the processes that govern the production and propagation of these mobile polar highs.

 

This is why record-breaking cold still occurs across the northern hemisphere. We're not necessarily pulling air right out of the Arctic lower troposphere. The true "source" of the coldest airmasses hasn't cooled, merely the conduit through which it must traverse has cooled. So, the equatorward effects aren't as stark as one might think.

[Front Ranger]

Phil explains things in such glorious detail. But here's common sense proof that he's not full of it: look at all the times an air mass has actually produced colder temps further south. It happens a lot...the air mass at lower levels often evolves as it sinks south. It's not a static relationship, it's fluid because of all the factors Phil listed.

[Phil]

Phil explains things in such glorious detail. But here's common sense proof that he's not full of it: look at all the times an air mass has actually produced colder temps further south. It happens a lot...the air mass at lower levels often evolves as it sinks south. It's not a static relationship, it's fluid because of all the factors Phil listed.

Thanks.

 

I do agree that overall, it becomes more difficult to achieve historic cold with warmer lower/middle tropospheric temperatures, however, when wave-cycles align properly, extremely cold, vertically coupled airmasses can propagate equatorward out of the polar/PV domain, and can be just as cold as airmasses decades and possibly even centuries ago.

 

This is exactly what happened in February of 2015, and theoretically, waves of a much deeper variety are possible.

[Front Ranger]

Thanks.

 

I do agree that overall, it becomes more difficult to achieve historic cold with warmer lower/middle tropospheric temperatures, however, when wave-cycles align properly, extremely cold, vertically coupled airmasses can propagate equatorward out of the polar/PV domain, and can be just as cold as airmasses decades and possibly even centuries ago.

 

This is exactly what happened in February of 2015, and theoretically, waves of a much deeper variety are possible.

 

Yeah, in my opinion the prohibiting factor for more frequent cold is simply a warmer world in general, not specifically a warmer Arctic.

 

Regardless, as you said extreme cold is still possible thanks to a coupled atmosphere. 

[wx_statman]

Well, I think it's more complicated than that.

 

Put simply, the deepest, most frigid polar airmasses technically arise aloft, within the polar vortex itself, in its lower/middle levels, poleward of 40-45N. The airmass within the polar vortex cools exponentially as O^3 and N^2O are molecularly dissociated under the dearth of solar radiation (which photochemically maintains production). Sometimes temperatures in the PV can plunge to levels as low as -100C.

 

The mobile polar high production associated with the strongest Arctic blasts over the middle latitudes arises when and planetary wave fluxes/related resonances disrupt the vortex, which is both kinetically and thermally coupled to the troposphere via diffusive and radiative processes. The stratospheric warming occurs as air sinks and pressures rise, hence adiabatically warming to levels as high as 50C. When the wave cycle completes, the airmass radiatively cools and dominant photochemical processes resume, which naturally leads to further pressure rises, etc. This process is occurring constantly even in years with strong PVs/+AOs.

 

I think you're over-complicating things here. A colder source airmass will advect colder air if it travels southward to lower latitudes. That's the premise, and it doesn't require advanced explanation. 

[wx_statman]

So simple.

 

You disagree with Phil on this. Why is he wrong?

 

Yes, this is actually a fairly simple premise. I appreciate Phil's input but he's talking about something different altogether. I'm talking about cold air advection when a polar airmass travels southward. If I somehow didn't make this clear, my apologies. 

[wx_statman]

The polar stratosphere and upper troposphere haven't warmed at all during the satellite era. In fact, polar temperatures above 300mb have cooled slightly. The arctic surface temperatures aren't exactly relevant given the processes that govern the production and propagation of these mobile polar highs.

 

This is why record-breaking cold still occurs across the northern hemisphere. We're not necessarily pulling air right out of the Arctic lower troposphere. The true "source" of the coldest airmasses hasn't cooled, merely the conduit through which it must traverse has cooled. So, the equatorward effects aren't as stark as one might think.

 

How are they not relevant? What about building and deepening of a surface airmass? Aren't surface conditions directly tied to the maintenance of an Arctic airmass? I don't have the knowledge base to critique what you're saying, but it sounds to me like you're missing something here. 

[Phil]

I think you're over-complicating things here. A colder source airmass will advect colder air if it travels southward to lower latitudes. That's the premise, and it doesn't require advanced explanation.

I'm trying to argue that the Arctic lower troposphere isn't actually the "source" for cold air across the NH. It's technically the upper troposphere and stratosphere poleward of 40N, which have not warmed at all during the satellite record.

 

The Arctic domain is extremely small. After a major SSW/PV breakdown event, for example, you'll often observe widespread frigid airmasses invade the midlatitudes, on both sides of the planet simultaneously. Obviously, the tiny Arctic domain isn't large enough (or cold enough) to account for all this frigid air.

[wx_statman]

Thanks.

 

I do agree that overall, it becomes more difficult to achieve historic cold with warmer lower/middle tropospheric temperatures, however, when wave-cycles align properly, extremely cold, vertically coupled airmasses can propagate equatorward out of the polar/PV domain, and can be just as cold as airmasses decades and possibly even centuries ago.

 

This is exactly what happened in February of 2015, and theoretically, waves of a much deeper variety are possible.

 

This is all I was looking for, within the context of this discussion. The common sense part that doesn't require advanced explanation. 

[Phil]

How are they not relevant? What about building and deepening of a surface airmass? Aren't surface conditions directly tied to the maintenance of an Arctic airmass? I don't have the knowledge base to critique what you're saying, but it sounds to me like you're missing something here.

I'll rephrase that. They're not nearly as relevant as many make them out to be. You're not just advecting cold air out out of the Arctic lower troposphere..if only it were that simple.

[wx_statman]

Yeah, in my opinion the prohibiting factor for more frequent cold is simply a warmer world in general, not specifically a warmer Arctic.

 

Regardless, as you said extreme cold is still possible thanks to a coupled atmosphere. 

 

I understand that this is your opinion, but I don't think there's a consensus out there on this subject. Its hard to say what's having more impact here - the expansion of the tropics/subtropics via expansion of the Hadley Cells, or the rather dramatic warming of the Arctic over the last 50 years.

[Phil]

I understand that this is your opinion, but I don't think there's a consensus out there on this subject. Its hard to say what's having more impact here - the expansion of the tropics/subtropics via expansion of the Hadley Cells, or the rather dramatic warming of the Arctic over the last 50 years.

It's interesting. Theoretically, the bolded could technically be one in the same, as expanding Hadley/Ferrel Cells would promote enhanced warming at higher latitudes. There's always that nagging chicken/egg paradox, though.

[wx_statman]

I'm trying to argue that the Arctic lower troposphere isn't actually the "source" for cold air across the NH. It's technically the upper troposphere and stratosphere poleward of 40N, which have not warmed at all during the satellite record.

 

The Arctic domain is extremely small. After a major SSW/PV breakdown event, for example, you'll often observe widespread frigid airmasses invade the midlatitudes, on both sides of the planet simultaneously. Obviously, the tiny Arctic domain isn't large enough (or cold enough) to account for all this frigid air.

 

I don't disagree with any of that (to the extent of my knowledge).

 

But we're still not talking about the same thing! 

[wx_statman]

I'll rephrase that. They're not nearly as relevant as many make them out to be. You're not just advecting cold air out out of the Arctic lower troposphere..if only it were that simple.

 

The lower troposphere is a part of the process, however. And a colder lower troposphere is going to have some effect on the CAA abilities of a southward-bound cA airmass. So surface temperatures are relevant. Its like we talked about the other day, nothing is a closed system in nature. And specifically to this discussion, this is the part of the process that I was talking about. 

[wx_statman]

It's interesting. Theoretically, the bolded could technically be one in the same, as expanding Hadley/Ferrel Cells would promote enhanced warming at higher latitudes. There's always that nagging chicken/egg paradox, though.

 

Yeah. I wish the scientific community had more concrete answers on this subject. Its very interesting indeed!  

[Phil]

I don't disagree with any of that (to the extent of my knowledge).

 

But we're still not talking about the same thing!

Maybe I misunderstood your argument. Apologize if that's the case, wasn't my intention.

 

I guess that, while I agree a warmer planet makes historic cold more difficult overall (especially without help from the stratosphere/upper levels, in which case it becomes nearly impossible), I agree with Flatiron that the lower level Arctic warming *itself* does little to prevent "top tier" blasts from occurring, because it's actually not the source for the said airmasses. The truly historic airmasses are created through photochemical processes way up in the stratosphere and upper troposphere (which have actually cooled statistically over the last 35+ years).

 

For example, you'll sometimes notice that after a major SSW event, not only will huge quantities of frigid air spill southward, but it will expand spatially and cool further, even as it spreads southward, out of the Arctic. Ever wonder why this might be? Another example. Very recently, a new world-record low temperature was recorded in/over Antarctica, despite the warmer planet overall. Ever wonder how something like that is possible at this point? The answer: thermo-molecular and photochemical processes, local to within the PV domain.

 

Fascinating stuff, in my opinion, as the processes in reference can occur in almost perfect insulation from external dynamics at times. It's amazing to watch.

 

[Jesse]

Maybe I misunderstood your argument. Apologize if that's the case, wasn't my intention.

 

I guess that, while I agree a warmer planet makes historic cold more difficult overall (especially without help from the stratosphere/upper levels, in which case it becomes nearly impossible), I agree with Flatiron that the lower level Arctic warming *itself* does little to prevent "top tier" blasts from occurring, because it's actually not the source for the said airmasses. The truly historic airmasses are created through photochemical processes way up in the stratosphere and upper troposphere (which have actually cooled statistically over the last 35+ years).

 

For example, you'll sometimes notice that after a major SSW event, not only will huge quantities of frigid air spill southward, but it will expand spatially and cool further, even as it spreads southward, out of the Arctic. Ever wonder why this might be? Another example. Very recently, a new world-record low temperature was recorded in/over Antarctica, despite the warmer planet overall. Ever wonder how something like that is possible at this point? The answer: thermo-molecular and photochemical processes, local to within the PV domain.

 

Fascinating stuff, in my opinion, as the processes in reference can occur in almost perfect insulation from external dynamics at times. It's amazing to watch.

 

 

The bottom line is, no one was making the argument that arctic surface warming was the sole factor. Just that it likely plays a role. From what I can tell, reading over this conversation, that has yet to be disproved...

 

It has been a fascinating read though!

[ShawniganLake]

Shawnigan Lake officially ended October with a mean temp of 50.0F which is exactly normal.  12.54" of rain was good for 2nd wettest October on record. 

[Phil]

The lower troposphere is a part of the process, however. And a colder lower troposphere is going to have some effect on the CAA abilities of a southward-bound cA airmass. So surface temperatures are relevant. Its like we talked about the other day, nothing is a closed system in nature. And specifically to this discussion, this is the part of the process that I was talking about.

Oh, I'm sure it has some effect..it has to, actually. Basic thermodynamics, all that lower level warmth doesn't just vanish after a SSW. Agree 100% there.

 

However, given the cooling observed in the upper troposphere and stratosphere, and the dynamics responsible for delivering those frigid, O^3/H^2O/CO^2 starved airmasses out of the polar upper levels, I'm not sure the effect has been very significant on a high frequency, airmass-to-airmass basis. That's very complicated and each airmass is unique, IMO.

 

Note how "historically significant" airmasses continue to occur around the globe periodically, despite the warmer background. The severity of those airmasses is determined by chemical processes largely independent of lower tropospheric temperatures. Though they've definitely decreased in frequency overall as the tropospheric circulations themselves are inhibiting the southward propagation of mobile polar high trains.

[Phil]

The bottom line is, no one was making the argument that arctic surface warming was the sole factor. Just that it likely plays a role. From what I can tell, reading over this conversation, that has yet to be disproved...

 

It has been a fascinating read though!

Here's food for thought, might explain why the PNW has struggled to "cash in" on the historic airmasses of recent years.

 

The truly frigid airmasses that arise through these upper level processes typically develop in climatologically "restricted" polar domains, usually near/under PV, which would suggest a difficult trajectory for arrival in the PNW.

 

Maybe with the lower tropospheric warming, the peripheral, lower level sourced Arctic airmasses that usually impact the PNW have been impacted to a higher degree relative to the deeper, supercooled airmasses with upper level ties?

[wx_statman]

Here's food for thought, might explain why the PNW has struggled to "cash in" on the historic airmasses of recent years.

 

The truly frigid airmasses that arise through these upper level processes typically develop in climatologically "restricted" polar domains, usually near/under PV, which would suggest a difficult trajectory for arrival in the PNW.

 

Maybe with the lower tropospheric warming, the peripheral, lower level sourced Arctic airmasses that usually impact the PNW have been impacted to a higher degree relative to the deeper, supercooled airmasses with upper level ties?

 

This is partially what I was trying to illustrate, at least with regards to specific observed trends along the western periphery of N. America over the last few decades. This is why I attempted to link the (up to) 6F-9F warming during DJF in Alaska with our lack of top-tier midwinter airmasses, compared to historical frequencies. 

 

Obviously with your level of education in this subject matter, you were able to put it more succinctly. 

[Front Ranger]

Here's food for thought, might explain why the PNW has struggled to "cash in" on the historic airmasses of recent years.

 

The truly frigid airmasses that arise through these upper level processes typically develop in climatologically "restricted" polar domains, usually near/under PV, which would suggest a difficult trajectory for arrival in the PNW.

 

Maybe with the lower tropospheric warming, the peripheral, lower level sourced Arctic airmasses that usually impact the PNW have been impacted to a higher degree relative to the deeper, supercooled airmasses with upper level ties?

 

Makes sense in some respects, but still doesn't explain why it's been mainly a mid winter phenomenon. The air masses that impacted PNW in Nov 2010, Feb 2011, and Dec 2013 were all upper level based.

[Front Ranger]

Oh, I'm sure it has some effect..it has to, actually. Basic thermodynamics, all that lower level warmth doesn't just vanish after a SSW. Agree 100% there.

 

However, given the cooling observed in the upper troposphere and stratosphere, and the dynamics responsible for delivering those frigid, O^3/H^2O/CO^2 starved airmasses out of the polar upper levels, I'm not sure the effect has been very significant on a high frequency, airmass-to-airmass basis. That's very complicated and each airmass is unique, IMO.

 

Note how "historically significant" airmasses continue to occur around the globe periodically, despite the warmer background. The severity of those airmasses is determined by chemical processes largely independent of lower tropospheric temperatures. Though they've definitely decreased in frequency overall as the tropospheric circulations themselves are inhibiting the southward propagation of mobile polar high trains.

 

Right, and if it were as simple as the Arctic being the source, this would be next to impossible, since the Arctic has run so much warmer than the past during the last decade or so.

 

What's more, the Arctic was actually quite a bit colder in the 1980s and 1990s than it is today, and yet the PNW still struggled to see top tier cold in January over that time frame. Going back to the regional aspect of the conversation.

[Phil]

Makes sense in some respects, but still doesn't explain why it's been mainly a mid winter phenomenon. The air masses that impacted PNW in Nov 2010, Feb 2011, and Dec 2013 were all upper level based.

Yeah, I don't have the answers, obviously. Was mostly just a thought experiment on my part. I think there's also an argument for back luck w/ midwinter timing.

[Front Ranger]

Yeah, I don't have the answers, obviously. Was mostly just a thought experiment on my part. I think there's also an argument for back luck w/ midwinter timing.

 

I absolutely think luck is part of it. The fact that major early season events have become more common backs that up. Not to mention the fact that climate/weather has a real tendency to go in streaks.

[wx_statman]

Right, and if it were as simple as the Arctic being the source, this would be next to impossible, since the Arctic has run so much warmer than the past during the last decade or so.

 

What's more, the Arctic was actually quite a bit colder in the 1980s and 1990s than it is today, and yet the PNW still struggled to see top tier cold in January over that time frame. Going back to the regional aspect of the conversation.

 

Is there a reason why you're saying this? That statement doesn't appear to fit into the discussion in this thread. 

[Jesse]

Is there a reason why you're saying this? That statement doesn't appear to fit into the discussion in this thread. 

 

He has been trying to frame the argument that way for a few days now. Still not quite sure why.

[wx_statman]

He has been trying to frame the argument that way for a few days now. Still not quite sure why.

 

It definitely wasn't a claim that I made. 

[Front Ranger]

He has been trying to frame the argument that way for a few days now. Still not quite sure why.

 

Because multiple people said it.

 

I didn't come up with "the Arctic is the source for cold air masses, therefore a warmer Arctic means less cold air masses."

[Front Ranger]

Anyone else concerned about the low sea ice on the arctic? Northern north America is running way above normal and destroying records. Meanwhile Asia is way below normal from Ukraine to Japan. I hope the pattern flips soon. We need a cold source for the winter and right now the arctic is downright balmy.

 

 

Less intense arctic air masses with a warmer source region that have more difficulty overcoming terrain issues? Yes, most likely.

 

 

Nobody has made that claim. Rather, a warmer Arctic has been sited as one of the contributing factors. And why wouldn't it be? Warmer source airmass = warmer result at lower latitudes. 

 

You guys said it.

[westcoastexpat]

Right, and if it were as simple as the Arctic being the source, this would be next to impossible, since the Arctic has run so much warmer than the past during the last decade or so.

 

What's more, the Arctic was actually quite a bit colder in the 1980s and 1990s than it is today, and yet the PNW still struggled to see top tier cold in January over that time frame. Going back to the regional aspect of the conversation.

 

I'm not exactly understanding why January not being top tier fits into the discussion. The Arctic could see negative anomalies and the PNW may still see record warmth, because if the pattern is not conducive to bringing that air southward, then it doesn't really matter.

 

I can't speak for everyone else, but my point about a balmy source is that, if the Arctic is very warm, no matter what the pattern, it's going to be difficult to get impressive cold to our latitude. And if the Arctic is cold, then it merely increases the odds.

 

I think think the newest piece of information that I've recently come across is how cold Russia has been... there is certainly a cold source.

[wx_statman]

Because multiple people said it.

 

I didn't come up with "the Arctic is the source for cold air masses, therefore a warmer Arctic means less cold air masses."

 

I'm not sure exactly where you're coming from here.

 

Nobody claimed its "as simple as the Arctic being the source"....

 

Right, and if it were as simple as the Arctic being the source, this would be next to impossible, since the Arctic has run so much warmer than the past during the last decade or so.

 

What's more, the Arctic was actually quite a bit colder in the 1980s and 1990s than it is today, and yet the PNW still struggled to see top tier cold in January over that time frame. Going back to the regional aspect of the conversation.

 

 

What are you trying to achieve in this discussion, Jared?

[wx_statman]

You guys said it.

 

There's no continuity in the argument you're trying to make here.

 

I'm not going to speak for other people, but with regards to my quote (of the three) - I have already addressed the fact that I was talking about specific cold airmasses. I have also addressed my logic behind the statement, and why it applies on a basic level.

 

Again I am left to wonder, what you trying to achieve in this discussion?