October 2016 Observations and Model Discussion for the Pacific Northwest

[Jesse]

You didn't notice all of Tim's posts on the 12z? Highly correlates to runs you won't like.

Ignore is a nice feature.

[Jesse]

Climo says we're almost certain to see ~75 degree weather at some point in October. Just gonna have to deal with it.

Nights don't look very crisp though. That's the deal breaker.

[BLI snowman]

Nights don't look very crisp though. That's the deal breaker.

 

Direct aftermath of the cool, wet afternoons this week. 

 

Won't be able to have it both ways 

[SilverFallsAndrew]

The fact is 1949 is the only October on record at PDX without a 70+ high. 

[Jesse]

Direct aftermath of the cool, wet afternoons this week.

 

Won't be able to have it both ways

Offshore flow baby!

 

Pray for a sharper ridge. Broad, humid ridges in October are agents of Satan.

[Kayla]

Nights don't look very crisp though. That's the deal breaker.

 

12z ECMWF seems like a much more likely pattern evolution....

[Phil]

The first week of October can be pretty wet. We've had some pretty good rain events in that timeframe.

 

I always like to see a more dynamic northern branch of the jet stream in October (and November). Generally a sign that polar air will be on the move a little more readily. A stable ridging regime this time of year isn't a great sign (1952, 1976). That being said, we've had some pretty wet Octobers precede terrible winters, like 2012 and 1943.

I don't think this holds true in Niña years. Stable ridging preceded 1978/79, 1988/89, 2013/14, even intermittently in 2008/09 (to a lesser extent).

 

Generally, it's crappier Niña years like 2005/06, 2007/08, 2011/12, etc that were preceded by strong northern jets/+EPO, though what is being modeled now isn't really a northern jet/+EPO as much as a hybrid Pacific jet/+PNA. There's less precedence for this sort of pattern in a Niña, though 2010 was similar.

[Phil]

The fact is 1949 is the only October on record at PDX without a 70+ high.

Hard to find many Niña Octobers with a 1949-esque look in the modern era given different circulation climatology. Almost looks like an antilog to this October.

 

http://i724.photobucket.com/albums/ww243/phillywillie/Mobile%20Uploads/3066BC1E-E59E-4293-945D-1E71DFF4BA66_zpswqqqhmca.png

[Jesse]

12z ECMWF seems like a much more likely pattern evolution....

Oh do tell.

[TT-SEA]

Jesse lies... he does not have me on ignore. He responds passive-aggressively many times before anyone even quotes me.

 

And another one for good measure.

[Front Ranger]

The first week of October can be pretty wet. We've had some pretty good rain events in that timeframe.

 

I always like to see a more dynamic northern branch of the jet stream in October (and November). Generally a sign that polar air will be on the move a little more readily. A stable ridging regime this time of year isn't a great sign (1952, 1976). That being said, we've had some pretty wet Octobers precede terrible winters, like 2012 and 1943. 

 

Yeah, I haven't noticed any significant correlations with October precip in neutral/Nina years and the following winter pattern.

 

With +ENSO, a ridgy/dry October is generally not a good sign, as you reference.

[BLI snowman]

I don't think this holds true in Niña years. Stable ridging preceded 1978/79, 1988/89, 2013/14, even intermittently in 2008/09 (to a lesser extent).

 

Generally, it's crappier Niña years like 2005/06, 2007/08, 2011/12, etc that were preceded by strong northern jets/+EPO, though what is being modeled now isn't really a northern jet/+EPO as much as a hybrid Pacific jet/+PNA. There's less precedence for this sort of pattern in a Niña, though 2010 was similar.

 

1978 and 2013 both had very active Septembers in the PNW that preceded a period of October ridging and were ENSO neutral winters. But our fall got an early start in both those years. 

 

I wouldn't consider Octobers like 2005 or 2011 to be especially active from a jet standpoint. Both of those months were pretty run-of-the-mill and devoid of significant anomalies of any sort here.

[Phil]

For the heck of it, here's how September finished @ 500mb:

 

http://i724.photobucket.com/albums/ww243/phillywillie/Mobile%20Uploads/17CB5EB6-D381-40D2-965A-D55B1671B8C4_zpsh6pvsitl.gif

 

Based on this, I found the -ENSO/+QBO years that best matched this pattern, the rolled them forward into October.

 

Here's how the analog aggregate looked for September:

 

http://i724.photobucket.com/albums/ww243/phillywillie/Mobile%20Uploads/EA821FB3-222D-48B5-A6CA-9BC7A4450B96_zps4xbh4wmi.png

 

Rolled forward into October, this is how the aggregate evolves:

 

http://i724.photobucket.com/albums/ww243/phillywillie/Mobile%20Uploads/5847A921-8F65-4A9B-9E68-567E11885523_zpsrwx36hyc.png

 

Relative to current modeling, these years were more Niña/-AAM overall, but otherwise similar with the Siberian/Eurasian ridging, and the GOA/NPAC trough.

[BLI snowman]

Yeah, I haven't noticed any significant correlations with October precip in neutral/Nina years and the following winter pattern.

 

With +ENSO, a ridgy/dry October is generally not a good sign, as you reference.

 

Really is a crapshoot overall. The idea that a +EPO October is a winter death knell is really silly, though. Octobers 1955 and 1956 showcase that nicely.

[SilverFallsAndrew]

SLE and EUG may struggle to hit 60 again today. 

[Phil]

1978 and 2013 both had very active Septembers in the PNW that preceded a period of October ridging and were ENSO neutral winters. But our fall got an early start in both those years.

 

I wouldn't consider Octobers like 2005 or 2011 to be especially active from a jet standpoint. Both of those months were pretty run-of-the-mill and devoid of significant anomalies of any sort here.

I thought you were solely referring to the October jet?

 

Let's test this theory. Since you're referring to strong October jets preceding "Arctic air mobilization", here's a comparison between all satellite era -ENSO Octobers that preceded DJFs with more frequent Arctic outbreaks in the NW:

 

 

Versus -ENSO Octobers preceding DJFs with more reduced Arctic intrusions/increased zonal flow:

 

http://i724.photobucket.com/albums/ww243/phillywillie/Mobile%20Uploads/2016-09/E2934547-5B6E-441F-9CC0-90E1E7C98F75_zpsa2z8o8qa.png

 

So, it seems that raging October jets tend to correlate with reduced Arctic air mobilization, rather than to the contrary.

[Phil]

Sorry, fixed the first image. Had originally uploaded the wrong one.

[BLI snowman]

I thought you were solely referring to the October jet?

 

Let's test this theory. Since you're referring to strong October jets preceding "Arctic air mobilization", here's a comparison between all satellite era -ENSO Octobers that preceded DJFs with more frequent Arctic outbreaks in the NW:

 

http://i724.photobucket.com/albums/ww243/phillywillie/Mobile%20Uploads/2016-09/5C3C67D6-4B41-4F6C-B55C-1C22BF882725_zpsln7hoxbm.png

 

Versus -ENSO Octobers preceding DJFs with more reduced Arctic intrusions/increased zonal flow:

 

http://i724.photobucket.com/albums/ww243/phillywillie/Mobile%20Uploads/2016-09/E2934547-5B6E-441F-9CC0-90E1E7C98F75_zpsa2z8o8qa.png

 

So, it seems that raging October jets tend to correlate with reduced Arctic air mobilization, rather than to the contrary.

 

Pretty cherry-picked method. If you're looking at October as it actually correlates to our precipitation in the PNW

 

Washington's 20 driest Octobers are:

 

1895, 1987, 2002, 1936, 1978, 1952, 1917, 1972, 1907, 1974, 1911, 1980, 2013, 1929, 1925, 1991, 1993, 1916, 1944, and 1976.

 

The majority of those are Nino or warm ENSO years. Generally warm/ridgy winters followed.

 

Washington's 20 wettest Octobers are:

 

1947, 1950, 1967, 1975, 1955, 1997, 2012, 1951, 2003, 1956, 1985, 1990, 1900, 2014, 1934, 1996, 1940, 2009, 1924, 1994

 

Far more negative ENSO years here on this list. These years were certainly more likely overall to produce an arctic airmass in the PNW lowlands.

 

Either way, plenty of room for outliers among either list. But clearly our wet Octobers had stronger jet tendencies, and they do have a tendency to produce cooler winters.

[Phil]

Really is a crapshoot overall. The idea that a +EPO October is a winter death knell is really silly, though. Octobers 1955 and 1956 showcase that nicely.

Of course they're not "death knells". They just statistically favor winters with reduced Arctic intrusions into the Western US during -ENSO.

 

The only satellite era October to feature a strong Pacific jet and be followed by a cold/blocky winter is 2010, though 1985 was borderline.

[Phil]

Pretty cherry-picked method. If you're looking at October as it actually correlates to our precipitation in the PNW

 

Washington's 20 driest Octobers are:

 

1895, 1987, 2002, 1936, 1978, 1952, 1917, 1972, 1907, 1974, 1911, 1980, 2013, 1929, 1925, 1991, 1993, 1916, 1944, and 1976.

 

The majority of those are Nino or warm ENSO years. Generally warm/ridgy winters followed.

 

Washington's 20 wettest Octobers are:

 

1947, 1950, 1967, 1975, 1955, 1997, 2012, 1951, 2003, 1956, 1985, 1990, 1900, 2014, 1934, 1996, 1940, 2009, 1924, 1994

 

Far more negative ENSO years here on this list. These years were certainly more likely overall to produce an arctic airmass in the PNW lowlands.

 

Either way, plenty of room for outliers among either list. But clearly our wet Octobers had stronger jet tendencies, and they do have a tendency to produce cooler winters.

This relationship will change with the ENSO sign. You're going to have to do some filtering here, IMO, because these years you're listing are a mess of different/contradictory systematic boundary states.

 

Would you use an El Niño year to analog a La Niña year? If you're not reflecting the proper systematic boundary conditions, you're analyzing a system that doesn't exist in reality.

[BLI snowman]

Of course they're not "death knells". They just statistically favor winters with reduced Arctic intrusions into the Western US during -ENSO.

 

The only satellite era October to feature a strong Pacific jet and be followed by a cold/blocky winter is 2010, though 1985 was borderline.

 

Many good winters (with arctic airmasses in our region) are preceded by Octobers with strong jetstream activity at some point or another. Some bad ones are, as well.

 

EPO reanalysis shows this

 

ftp://ftp.cdc.noaa.gov/Public/gbates/teleconn/epo.reanalysis.t10trunc.1948-present.txt

[Phil]

Many good winters (with arctic airmasses in our region) are preceded by Octobers with strong jetstream activity at some point or another. Some bad ones are, as well.

 

EPO reanalysis shows this

 

ftp://ftp.cdc.noaa.gov/Public/gbates/teleconn/epo.reanalysis.t10trunc.1948-present.txt

A few points here.

 

1) How many are Niñas? More importantly, how many are Niñas that took place since the late 1970s?

 

2) Most Niña Octobers have +EPOs..it isn't exactly a great reflector of the NPAC jet by longitude. Using zonal winds or 500mb heights over the NEPAC will usually reflect the nature of NPAC jet more accurately, in my opinion.

 

When looking at the data, it's fairly apparent that a stronger NPAC jet during a -ENSO October generally correlates to reduced Arctic intrusions into the western US. That doesn't mean the relationship is perfect...note 2010/11.

[BLI snowman]

A few points here.

 

1) How many are Niñas? More importantly, how many are Niñas that took place since the late 1970s?

 

2) Most Niña Octobers have +EPOs..it isn't exactly a great reflector of the NPAC jet by longitude. Using zonal winds or 500mb heights over the NEPAC will usually provide higher accuracy.

 

Most of our better Ninas since the late 1970s had some sustained +EPO or strong jet activity in October. 1984 and 1995 included. 

[Front Ranger]

Most of our better Ninas since the late 1970s had some sustained +EPO or strong jet activity in October. 1984 and 1995 included.

Plus, I don't see the point of excluding neutral ENSO years like 1990, 1996, etc. So far, we are just dealing with a weakly -ENSO fall.

[Phil]

Most of our better Ninas since the late 1970s had some sustained +EPO or strong jet activity in October. 1984 and 1995 included.

Okay, that doesn't say much considering that's true of almost all -ENSO Octobers.

 

When looking at the data, it's clear that -ENSO Octobers with stronger NPAC jets correlate to reduced Arctic air intrusion into the Western US during D/J/F. I'm not sure why you're denying this.

[Phil]

Plus, I don't see the point of excluding neutral ENSO years like 1990, 1996, etc. So far, we are just dealing with a weakly -ENSO fall.

Eh, I included 1996/97. I did exclude 1990/91, because it featured a +ENSO regime in O/N/D, transitioning into a true Niño background state for winter/spring. Was just a peculiar year.

 

Should I include years like 2014/15 and 2004/05?

[BLI snowman]

Okay, that doesn't say much considering that's true of almost all -ENSO Octobers.

 

When looking at the data, it's clear that -ENSO Octobers with stronger NPAC jets correlate to reduced Arctic air intrusion into the Western US during D/J/F. I'm not sure why you're denying this.

 

Because you're not using any hard data and are literally just cherry picking years to fit into a narrative. The fact that you even grouped 1985 and 1996 with the "reduced arctic air intrusion" list says a lot. Those were two of the better winters in recent history for large parts of our region. And 1998-99 had our coldest individual airmass in the last 20 years. Pretty unscientific stuff.

[Phil]

Even if I include 1990/91, it doesn't change the result. Zonal winters on top, cold/blocky winters on the bottom. This looks fairly straightforward to me.

 

 

[Jesse]

Been awhile since we've seen a nice, pointless analog war.

[Phil]

Because you're not using any hard data and are literally just cherry picking years to fit into a narrative. The fact that you even grouped 1985 and 1996 with the "reduced arctic air intrusion" list says a lot. Those were two of the better winters in recent history for large parts of our region. And 1998-99 had our coldest individual airmass in the last 20 years. Pretty unscientific stuff.

Uh, what? DJF 1985/86 warm and ridgy, and DJF 1996/97 was warmer than average over most of the PNW.

 

I'm not analyzing brief/fluky events that scrape northern areas in a zonal regime. That's missing the point of this analysis.

[BLI snowman]

Uh, what? DJF 1985/86 warm and ridgy, and DJF 1996/97 was warmer than average over most of the PNW.

 

I'm not analyzing brief/fluky events that scrape northern areas in a zonal regime. That's missing the point of this analysis.

 

Arctic airmasses in the PNW are by their very definition brief and flukey events in a zonal regime. That's the nature of our climate. 

[Phil]

Arctic airmasses in the PNW are by their very definition brief and flukey events in a zonal regime. That's the nature of our climate.

Exactly, which is why blocky winters produce more Arctic blasts than zonal winters, and are consistently colder. In the years I analyzed, this held to approximately a 4/1 ratio.

 

Generally speaking, winters featuring a more zonal pattern produce fewer Arctic outbreaks, and are warmer overall, while winters that are blocky produce more Arctic outbreaks, and are generally colder overall.

[Phil]

So, when I separated the aforementioned winters by their patterns, and rolled back to October, the zonal winters were generally preceded by a stronger NPAC jet in that month, while the blockier winters were generally preceded by a weaker NPAC jet. This correlation isn't perfect by any means, but it's fairly straightforward.

[Phil]

If I start with the NPAC Jet, and roll forward, I get a very similar result (with a time inversion, obviously).

[Kayla]

Oh do tell.

 

I'm sure you saw by now but just one 70º (Monday) shown for PDX over the next 10 days. EPS only tops out at 69º over the next 15 days. 

 

Parade of wet Pacific systems continue to pass through the region late in the run as well.

[Jesse]

I'm sure you saw by now but just one 70º (Monday) shown for PDX over the next 10 days. EPS only tops out at 69º over the next 15 days.

 

Parade of wet Pacific systems continue to pass through the region late in the run as well.

I saw the 12z Euro, but I don't have access to the highs. That's awesome.

 

I did notice that EPS support is becoming more solid for the uber-active pattern that is being advertised in the 8-10 day range. Usually a good sign.

[Front Ranger]

Eh, I included 1996/97. I did exclude 1990/91, because it featured a +ENSO regime in O/N/D, transitioning into a true Niño background state for winter/spring. Was just a peculiar year.

 

Should I include years like 2014/15 and 2004/05?

 

What about 1992? I don't think that was more +ENSO than 1980, for instance.

[Phil]

What about 1992? I don't think that was more +ENSO than 1980, for instance.

It was similar in the tropics, but much more +ENSO/+AAM in the off-equator/extratropical domain(s).

 

I think the 1990s (in general) are a poor match to today's system state. Raging solar, weak BDC, frigid polar strat/+NAM, etc.

[snow_wizard]

For the heck of it, here's how September finished @ 500mb:

 

 

Based on this, I found the -ENSO/+QBO years that best matched this pattern, the rolled them forward into October.

 

Here's how the analog aggregate looked for September:

 

 

Rolled forward into October, this is how the aggregate evolves:

 

 

Relative to current modeling, these years were more Niña/-AAM overall, but otherwise similar with the Siberian/Eurasian ridging, and the GOA/NPAC trough.

 

 

So, when I separated the aforementioned winters by their patterns, and rolled back to October, the zonal winters were generally preceded by a stronger NPAC jet in that month, while the blockier winters were generally preceded by a weaker NPAC jet. This correlation isn't perfect by any means, but it's fairly straightforward.

 

This kind of fits my findings that suggest higher than normal surface pressure off the West Coast in October is often a good sign for us.  I think we could get away with a brief stormy period this month, but I hope it quickly transitions back to blocky if it happens.

[TT-SEA]

This kind of fits my findings that suggest higher than normal surface pressure off the West Coast in October is often a good sign for us.  I think we could get away with a brief stormy period this month, but I hope it quickly transitions back to blocky if it happens.

 

 

Does not look brief right now.