November 2017 PNW Discussion Thread

[umadbro]

Anyone have a cherry picker around?

[ShawniganLake]

27 days with rain at YVR in November. Tied the record from 1953. Total amounts were near normal. It rained often, but not that heavy.

[VancouverIslandSouth]

27 days with rain at YVR in November. Tied the record from 1953. Total amounts were near normal. It rained often, but not that heavy.

 

Same here, this area ended up with 27 days of measurable precip but with a total only around 5".

[ShawniganLake]

Same here, this area ended up with 27 days of measurable precip but with a total only around 5".

We are well past 12” here, with an average closer to 9”. What’s your average down that way

[snow_wizard]

The EPS control model shows an Arctic blast just after day 10.

[Gradient Keeper]

The EPS control model shows an Arctic blast just after day 10.

Oh? Does the block retrograde, or flatten with new Aleutian block setting up 160-150 W?

[snow_wizard]

Oh? Does the block retrograde, or flatten with new Aleutian block setting up 160-150 W?

 

A trough rotates around the top and digs it back.

 

The block moves back to around 140 but is highly amplified.

[Gradient Keeper]

A trough rotates around the top and digs it back.

 

The block moves back to around 140 but is highly amplified.

Must have real nice tilt to it also.

[SilverFallsAndrew]

Mark Nelsen says no snow in December at PDX.

[Front Ranger]

There is no NAO connection to PNW weather.

 

There is an NAO connection to PNW climate.

Your arguments can be inconsistent sometimes.

 

If it's climate, why would you cite model runs?

 

Like I've said, a more favorable climate regime does favor both -NAO and Pacific blocking. But I don't see evidence for much correlation beyond that.

[ShawniganLake]

A chilly 38F here with rain moving in. Tomorrow looks pretty wet across SW BC with heavy mountain snow.

[SilverFallsAndrew]

And it is December now. Let us please post on the appropriate thread.

[snow_wizard]

Mark Nelsen says no snow in December at PDX.

 

Absolutely insane to make that kind of proclamation.  There is actually a pretty reasonable chance at some point.

[SilverFallsAndrew]

Absolutely insane to make that kind of proclamation.  There is actually a pretty reasonable chance at some point.

 

In fairness he entered a weather contest. He had to make a prediction in that case. 

[Phil]

Your arguments can be inconsistent sometimes.

 

If it's climate, why would you cite model runs?

 

Like I've said, a more favorable climate regime does favor both -NAO and Pacific blocking. But I don't see evidence for much correlation beyond that.

Seems like you're having a hard time tonight.

 

The NAO/PNW climate relationship is fairly linear. The NAO relationship to PNW weather is non-linear/inconsistent, but it still affects PNW weather, in various ways, depending on the nature of the overall pattern. Just because the teleconnection is inconsistent doesn't mean it's not there.

[Farmboy]

Mark Nelsen says no snow in December at PDX.

. Wow, warm bias much?

[Jesse]

Looks like PDX will end up +0.8 for November. Pretty close to average, like October.

[TT-SEA]

38 here with a nice sunrise on the way.   

 

SEA ended up at +1.3 for November with 8.63 inches of rain (2+ inches above normal).    SEA is also 10.30 inches above normal for the year of 2017.

[Front Ranger]

Seems like you're having a hard time tonight.

 

The NAO/PNW climate relationship is fairly linear. The NAO relationship to PNW weather is non-linear/inconsistent, but it still affects PNW weather, in various ways, depending on the nature of the overall pattern. Just because the teleconnection is inconsistent doesn't mean it's not there.

 

I don't disagree with any of that.

 

It just seemed like you were trying to show a direct causal relationship at times between NAO and PNA (in the short term), which is what I've explained I don't see much evidence for.

[VancouverIslandSouth]

We are well past 12” here, with an average closer to 9”. What’s your average down that way

 

There aren't any official stations with climate data nearby, but YYJ is at 6". Looking at some long running stations around UVic I'm guessing the average for this area is probably between 4.5~5".

[Front Ranger]

Looks like PDX will end up +0.8 for November. Pretty close to average, like October.

 

Pretty stark difference across the region between the two months (Nov hasn't updated through the 30th yet, but that won't change much).

 

 

[Jesse]

Pretty stark difference across the region between the two months (Nov hasn't updated through the 30th yet, but that won't change much).

 

Yep. I never said anything about the region.

[Front Ranger]

Yep. I never said anything about the region.

 

Yep. Never said you did. Just making a comment related to yours. 

[Phil]

I don't disagree with any of that.

 

It just seemed like you were trying to show a direct causal relationship at times between NAO and PNA (in the short term), which is what I've explained I don't see much evidence for.

Uh, there is a direct, harmonic relationship between the PNA/NAO. That's why they've shared signs in over 85% of winters since 1950.

 

Denying that the PNA and NAO constructively resonate is analogous to denying that ENSO influences the PNA.

[Phil]

For the record, since 1950, the seasonal correlation coefficient between the PNA and NAO is stronger then the correlation coefficient between the PNA and PDO.

[Front Ranger]

Uh, there is a direct, harmonic relationship between the PNA/NAO. That's why they've shared signs in over 85% of winters since 1950.

 

Denying that the PNA and NAO constructively resonate is analogous to denying that ENSO influences the PNA.

 

I'm open minded about it, man, I just don't see the direct relationship. Why are they so decoupled in so many months then? I don't see evidence that if the NAO goes negative in any given week or month, the PNA is likely to follow suit, or vice versa.

 

Like I've said, I totally agree that a system state that favors North Atlantic blocking will also often favor North Pacific blocking, resulting in a higher likelihood of both PNA/NAO being negative.

[Phil]

I'm open minded about it, man, I just don't see the direct relationship. Why are they so decoupled in so many months then? I don't see evidence that if the NAO goes negative in any given week or month, the PNA is likely to follow suit, or vice versa.

 

Like I've said, I totally agree that a system state that favors North Atlantic blocking will also often favor North Pacific blocking, resulting in a higher likelihood of both PNA/NAO being negative.

It's a seasonal correlation, though, not a monthly one. The conduits to both run through the IO/Indo-Pacific, and the corresponding Walker/Hadley intensity ratio(s).

 

Higher frequency interference from the MJO/intraseasonal chaos sometimes masks the lower frequency correlation from a weekly/subseasonal perspective.

[Phil]

I'll run the seasonal correlation coefficient between the NAO and PNA on ESRL and post it here. It's very impressive.

[Front Ranger]

I'll run the seasonal correlation coefficient between the NAO and PNA on ESRL and post it here. It's very impressive.

I believe in the seasonal correlation. Of course, correlation doesn't equal causation.

 

I just think a few people on here were getting confused thinking that there was a direct, short term correlation between NAO and PNA.

[Phil]

I believe in the seasonal correlation. Of course, correlation doesn't equal causation.

 

I just think a few people on here were getting confused thinking that there was a direct, short term correlation between NAO and PNA.

From a short term/weekly standpoint, I agree with you. The relationship between the NAO & PNA is mostly a longer term phenomenon. However, it's also quite unique, because there's little statistical relationship between the PNA and the EPO/AO.

 

There's definitely a seasonal/yearly-scale relationship between the PNA and NAO, centered within boreal winter, however the strongest statistical relationship is found on a longer term, decadal/multi-decadal time resolution.

[Phil]

That said, the relationship isn't just a result of blocky patterns reflecting on both indexes in the long run. There's no statistical correlation between the PNA and EPO, and the correlation between the PNA and the WPO and NAM/AO is much weaker as well.

[Front Ranger]

From a short term/weekly standpoint, I agree with you. The relationship between the NAO & PNA is mostly a longer term phenomenon. However, it's also quite unique, because there's little statistical relationship between the PNA and the EPO/AO.

 

There's definitely a seasonal/yearly-scale relationship between the PNA and NAO, centered within boreal winter, however the strongest statistical relationship is found on a longer term, decadal/multi-decadal time resolution.

 

Sure. But since -EPO/-PNA is more likely to bring serious cold to the PNW than -PNA/-NAO (all else being equal), you'll find people care more about PNA/EPO here.