La Niña/Winter 2016-17 Discussion

[Isotherm]

2 hours ago, heavy_wx said:

There is a causality issue with this; I think that coherent tropical convection tends to have a larger influence on the mid-latitude longwave pattern. A ridge forced in the Gulf of Alaska by coherent tropical convection would favor warmer SSTs near the Alaskan coast and a +PDO, instead of the +PDO itself causing the ridging.

I would tend to agree with you that the tropical forcing is likely much more influential. The "warm blob" of the NPAC was often implicated in the 2013-2015 period by numerous sources, but in those cases as well, I generally believe the warm pool was moreso the resultant effect rather than causative (although positive feedback can occur). I do think the PDO - namely, changes in SSTA profiles, of the N/E Pacific does have an impact in reducing or enhancing angular momentum and therefore contributing to the ridge/trough orientation. But even still, the effect is probably far inferior to the deep convection related driving, as you said.

[Isotherm]

9 hours ago, snowman19 said:

I can't believe this westerly QBO event is still gaining strength. The way it is forecasted will have to change after this year

My guess is that this reset will remain highly anomalous (i.e., not a harbinger of a new trend) and is unlikely to be repeated for decades. We had a unique combination of circumstances last year which produced quite a bit of additional westerly shear stress in the stratosphere, the primary factor, of course, being the super charged +ENSO event with periods of record angular momentum, coupled with expansive, deep tropical convection across the Pacific (which likely added in inducing WAF up through the trop-->strat, and destructively interfering with downward propagating easterly winds in the stratosphere).

[bluewave]

11 hours ago, Isotherm said:

 

 

The difficulty is isolating the variable of the PDO index as the principal determinant of the z500 pattern, particularly in light of the fact that the sample size for +PDO/Nina's is extremely small.

When we examine +PDO/Weak Nina years such as 1995-96, and 1996-97, their z500 patterns featured a much more retracted jet w/ the mid level ridging centered closer to the longitude of the Aleutians. Conversely, the +PDO/Nina's of 1983-84 and 1984-85 featured the mid level ridging at a longitude further east (centered south of Alaska). I believe the PDO was likely influential in impacting the orientation; however, the disparities in tropical forcing location/magnitude were also significant for 1983-85 vs 1995-97. The latent heat release, associated jet dynamics and concomitant rossby wave train propagation / wave activity flux likely played a role.

The other challenge in determining the orientation and the amount of ridging near western North America during a +PDO La Nina is that there

isn't always a one to one relationship with the strength of the actual +PDO winter value. The +PDO La Nina winter of 2000-2001 had an average PDO

reading of +0.47 with a strong ridge over western North America. During the 1984-1985 La Nina event the ridge was further west and the PDO

reading higher at +0.91. So other factors like WPAC forcing of the wave train and the value of the slightly further west NPM plays an important role.

Not to mention how other teleconnection indices interact with the Pacific pattern. This year we continue to see very warm to record SST's at times

over the WPAC which may maintain a +PDO/+NPM western North America ridge regime. So the bar for +PDO influence may only need to be

weakly positive or what some might call warm neutral to exert an influence on the actual pattern. +PDO La Ninas tend to have this stronger ridging

closer to or over western North America than their -PDO counterparts which can often have a deep vortex right over Alaska and portions of NW Canada.

The big takeaway from this is that the actual sensible weather pattern this winter will probably be determined by some measure of +PDO WPAC forcing

along with the La Nina influence on the PAC Jet . The rest of the pattern will come down to other important inputs like the Arctic and Atlantic.

http://research.jisao.washington.edu/pdo/PDO.latest.txt

 

2000    -2.00  -0.83   0.29   0.35  -0.05  -0.44  -0.66  -1.19  -1.24  -1.30  -0.53   0.52
2001      .60    .29   0.45  -0.31  -0.30  -0.47  -1.31  -0.77  -1.37  -1.37  -1.26  -0.93

 

1984     1.50   1.21   1.77   1.52   1.30   0.18  -0.18  -0.03   0.67   0.58   0.71   0.82
1985     1.27   0.94   0.57   0.19   0.00   0.18   1.07   0.81   0.44   0.29  -0.75   0.38

 

 

Classic stronger -PDO La Nina winter which no snowlover ever wants to see. 

1998     0.83   1.56   2.01   1.27   0.70   0.40  -0.04  -0.22  -1.21  -1.39  -0.52  -0.44
1999    -0.32  -0.66  -0.33  -0.41  -0.68  -1.30  -0.66  -0.96  -1.53  -2.23  -2.05  -1.63
2000    -2.00  -0.83   0.29 

2007**   0.01   0.04  -0.36   0.16  -0.10   0.09   0.78   0.50  -0.36  -1.45  -1.08  -0.58
2008**  -1.00  -0.77  -0.71  

-1.34  -2.33  -1.79
2012**  -1.38  -0.85  -1.05 

 

 

 

[snowman19]

11 hours ago, heavy_wx said:

There is a causality issue with this; I think that coherent tropical convection tends to have a larger influence on the mid-latitude longwave pattern. A ridge forced in the Gulf of Alaska by coherent tropical convection would favor warmer

2 hours ago, bluewave said:

The other challenge in determining the orientation and the amount of ridging near western North America during a +PDO La Nina is that there

isn't always a one to one relationship with the strength of the actual +PDO winter value. The +PDO La Nina winter of 2000-2001 had an average PDO

reading of +0.47 with a strong ridge over western North America. During the 1984-1985 La Nina event the ridge was further west and the PDO

reading higher at +0.91. So other factors like WPAC forcing of the wave train and the value of the slightly further west NPM plays an important role.

Not to mention how other teleconnection indices interact with the Pacific pattern. This year we continue to see very warm to record SST's at times

over the WPAC which may maintain a +PDO/+NPM western North America ridge regime. So the bar for +PDO influence may only need to be

weakly positive or what some might call warm neutral to exert an influence on the actual pattern. +PDO La Ninas tend to have this stronger ridging

closer to or over western North America than their -PDO counterparts which can often have a deep vortex right over Alaska and portions of NW Canada.

The big takeaway from this is that the actual sensible weather pattern this winter will probably be determined by some measure of +PDO WPAC forcing

along with the La Nina influence on the PAC Jet . The rest of the pattern will come down to other important inputs like the Arctic and Atlantic.

http://research.jisao.washington.edu/pdo/PDO.latest.txt

 

2000    -2.00  -0.83   0.29   0.35  -0.05  -0.44  -0.66  -1.19  -1.24  -1.30  -0.53   0.52
2001      .60    .29   0.45  -0.31  -0.30  -0.47  -1.31  -0.77  -1.37  -1.37  -1.26  -0.93

 

1984     1.50   1.21   1.77   1.52   1.30   0.18  -0.18  -0.03   0.67   0.58   0.71   0.82
1985     1.27   0.94   0.57   0.19   0.00   0.18   1.07   0.81   0.44   0.29  -0.75   0.38

 

 

Classic stronger -PDO La Nina winter which no snowlover ever wants to see. 

1998     0.83   1.56   2.01   1.27   0.70   0.40  -0.04  -0.22  -1.21  -1.39  -0.52  -0.44
1999    -0.32  -0.66  -0.33  -0.41  -0.68  -1.30  -0.66  -0.96  -1.53  -2.23  -2.05  -1.63
2000    -2.00  -0.83   0.29 

2007**   0.01   0.04  -0.36   0.16  -0.10   0.09   0.78   0.50  -0.36  -1.45  -1.08  -0.58
2008**  -1.00  -0.77  -0.71  

-1.34  -2.33  -1.79
2012**  -1.38  -0.85  -1.05 

 

 

 

SSTs near the Alaskan coast and a +PDO, instead of the +PDO itself causing the ridging.

A neutral or weak positive or weak negative PDO doesn't exert enough influence to cause positive feedback into the pattern. There are those who think the PDO doesn't force anything and that it's merely the result of the longwave pattern not the cause of it. Putting the PDO aside for a minute here. Assuming a dominate +PNA this winter is a real big mistake in my view. You have a background La Niña state during a +QBO. The resultant forcing from that very strongly favors a poleward Aleutian ridge of high pressure during winter. This has been proven in several studies. Just my opinion, I'd be very careful if your forecast is for a dominating +PNA this winter, that is very unlikely 

[packbacker]

1 hour ago, snowman19 said:

A neutral or weak positive or weak negative PDO doesn't exert enough influence to cause positive feedback into the pattern. There are those who think the PDO doesn't force anything and that it's merely the result of the longwave pattern not the cause of it. Putting the PDO aside for a minute here. Assuming a dominate +PNA this winter is a real big mistake in my view. You have a background La Niña state during a +QBO. The resultant forcing from that very strongly favors a poleward Aleutian ridge of high pressure during winter. This has been proven in several studies. Just my opinion, I'd be very careful if your forecast is for a dominating +PNA this winter, that is very unlikely 

Agree...weak -enso/+QBO doesn't favor a +PNA.  The only 2 weak -enso, +QBO with +PDO (regardless of strength and using jisao) are 86/14, that I could find.   86 had a dominate +PNA throughout winter and 14 had a dominate +PNA/-EPO for much of January.  Arguments can be made both ways...

[Isotherm]

To add to the obfuscation: progged velocity potential is rather anti-Nina esque as we progress into mid November w/ very atypical tropical forcing. We see the continued decoupled system w/ decreasing angular momentum and concomitant jet retraction, yet still obstinately Nino forcing tendencies.

 

[Morris]

Latest values:

Nino 1.2: +0.0 (-0.2)

Nino 3: -0.6 (-0.1)

Nino 3.4: -0.8 (-)

Nino 4: -0.6 (-0.2)

http://www.cpc.ncep.noaa.gov/data/indices/wksst8110.for

[snowman19]

The new Euro weeklies and now the Euro monthly forecast for this winter is ugly. Real ugly. As in the 2011-2012 winter with a huge Bering Sea low, +EPO, no blocking, zonal flow and the polar vortex and cold stuck in Siberia all winter. Euro monthly:

[dmillz25]

37 minutes ago, snowman19 said:

The new Euro weeklies and now the Euro monthly forecast for this winter is ugly. Real ugly. As in the 2011-2012 winter with a huge Bering Sea low, +EPO, no blocking, zonal flow and the polar vortex and cold stuck in Siberia all winter. Euro monthly:

Wow what a shift 

[Morris]

 

[snowman19]

CanSIPS actually looks like the Euro. New CESM has gone blowtorch too

[SnowHole413]

With the models flipping and flopping so much I would say it's time to take a step back from the models and see how everything evolves from here. Let's get the pack going in Canada and see how the nao and ao respond from there. It's only November 8th..

[WEATHERBUFF]

2 hours ago, dmillz25 said:

Wow what a shift 

Yes like euro winter forecasts are so accurate and consistent!

[Stebo]

I wouldn't put much stock in those long range models, especially this far in advance. I will say this though there is a concern with all the cold being on one side of the globe, 2011-12 had this exact problem and we know how that winter went.

[Stebo]

3 hours ago, snowman19 said:

CanSIPS actually looks like the Euro. New CESM has gone blowtorch too

That looks more zonal on the CANSIPS and the CESM you posted is for October which is done and November which is almost 10 days in already... You might want to actually look at what you are posting before you toss out a troll post.

[snowman19]

6 minutes ago, Stebo said:

6 minutes ago, Stebo said:

That looks more zonal on the CANSIPS and the CESM you posted is for October which is done and November which is almost 10 days in already... You might want to actually look at what you are posting before you toss out a troll post.

No, look again, it compares the October forecast to the new one that came out this month. Take your own advice and you look again

[Stebo]

1 minute ago, snowman19 said:

 

I couldn't even tell because it is blurry as hell and you don't directly link to your sources or upload the images like normal. Furthermore these long range models are prone to wild changes so, it would be a tread lightly situation.

[packbacker]

I don't put to much stock in any one seasonal but when they all points towards warmth it makes you wonder.  BN Dec seems like a high prob...maybe not. 

[snowman19]

1 minute ago, packbacker said:

I don't put to much stock in any one seasonal but when they all points towards warmth it makes you wonder.  BN Dec seems like a high prob...maybe not. 

Agree here. December in my opinion is the "coldest" month of this winter. I see it as being normal maybe slightly below normal possibly. Favoring a normal month at the moment

[Met1985]

29 minutes ago, bluewave said:

Yeah, all these long range model forecasts past the 6-10 day ensemble means are a big roll of the dice which can sometimes come close or other times result in a big miss.

This October is starting with an unprecedented set of initial conditions before the winter that the models have never experienced before.

 

1) Unprecedented complete Pacific warming event beginning in the summer of 2013 culminating with the extreme super Nino and +PDO and +NPM in recent winters.

 How do the models handle this residual Nino forcing which is still evident as this La Nina is beginning to take shape?

The Pacific pattern this October with the Nino-like record Alaskan ridge getting undercut by the Nina Pacific Jet and displaced Aleutian Low to the PAC NW

producing the wettest month on record for Spokane, WA.

 

2) Record low sea ice in the Arctic along with record extreme warmth and 500 mb and -AO blocking producing near record snow and cold over Eurasia.

Resulting pattern for October into the first half of November is North America getting flooded by mild Pacific air.

 

3) record SST warmth off the US East Coast for October.

 

So it will be interesting to see how all of these competing influences contribute to the December through March pattern.

 

 

 

 

 

A great way of pointing out this is not a normal cold season we are going into. Lots of variables on the table.

[uncle W]

speaking of variables, 1966 had its share of record warmth each month...The temp on Dec. 9th reached 66 which set a new record high...(since broken)...there was snow in the air on Dec. 13th...there was four days in a row with temps in the 60's from the 8th-11th...it reached 68 on Jan. 24th, 1967... a new record high...there was three straight days 60 or higher from Jan. 23rd-25th...there was snow in the air Jan. 28th...Feb. 2nd had a high of 58...A new record high...(since broken)...there was a cold front that evening that had rain and wet snow with it late that evening...on Feb. 5th it was 48 degrees....Feb. 6th saw snow and arctic cold and a blizzard the next day...Feb. 15th it was 60 in NYC...there was snow in the air on the 17th...March 3rd was 64 in NYC...a new record high (since broken)...there was 2" of snow on the morning of the 5th...March 11th was 72 in NYC...there was a cold rain two days later...March 14th was 63 in NYC...3" of snow and sleet fell a day later...

[snowman19]

Update from the CPC: 

[snowman19]

From Mike Ventrice, NMME predicting a solid -PDO by March, falling all winter: 

[packbacker]

What appears to be a failed attempt at a pattern change to BN for the east in mid/end of Nov is telling.  I for one am surprised, I thought Nov would see a flip and Dec would be BN.   Not ready to write off Dec but...

Edit: I just picked some nina's off the top of my head that I remembered being warm/cold.

[WEATHERBUFF]

57 minutes ago, packbacker said:

What appears to be a failed attempt at a pattern change to BN for the east in mid/end of Nov is telling.  I for one am surprised, I thought Nov would see a flip and Dec would be BN.   Not ready to write off Dec but...

Edit: I just picked some nina's off the top of my head that I remembered being warm/cold.

It depends on what normal means if we get to the 1981 2010 averages that would be below notmal for todays climate.

[snowman19]

We now have a healthy looking weak CP Nina. Region 3.4 has hit the coldest daily values of this event over the last week and a half

[snowman19]

2 hours ago, bluewave said:

It will be interesting to see what kind of curveball this unusual La Nina throws us for the December to March since its not following the standard La Nina script.

The Aleutian Low continues to be displaced to the south of the usual position in October and November for the La Nina 500 mb composite.

This odd location for the low combined with the general NP pattern has produced the strongest jet on record for this time of year across the Pacific 

from 30-50N. This has been flooding North America with mild Pacific air.

 

Oct 16 vs the La Nina composite

 

 

November 2016 so far vs composite

 

 

 

New record PAC jet 30-50 N for October by a wide margin

 

 

 

 

 

 

 

 

 

 

Good post. That jet is mostly +AAM driven

[snowman19]

NOAA has just issued a La Niña advisory for this winter. A La Niña is likely through March: http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso_advisory/ensodisc.shtml 

[uofmiami]

6 minutes ago, snowman19 said:

NOAA has just issued a La Niña advisory for this winter. A La Niña is likely through March: http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso_advisory/ensodisc.shtml 

Synopsis:  La Niña conditions are present and slightly favored to persist (~55% chance) through winter 2016-17.

La Niña conditions were observed during October, with negative sea surface temperature (SST) anomalies in early November stretching across most of the eastern and central equatorial Pacific Ocean [Fig. 1]. With the exception of the Niño1+2 region, the Niño region indices remained negative over the last month, with the latest weekly value of the Niño-3.4 index at -0.8°C [Fig. 2]. The upper-ocean heat content also remained below average during October [Fig. 3], reflecting below-average temperatures at depth [Fig. 4]. Convection was suppressed over the central tropical Pacific and enhanced over Indonesia [Fig. 5]. The lower-level easterly winds were weakly enhanced near and west of the International Date Line, and anomalously westerly upper-level winds were mainly west of the International Date Line. Overall, the ocean and atmosphere system reflected weak La Niña conditions.

The multi-model averages favor La Niña conditions (3-month average Niño-3.4 index less than or equal to -0.5°C) continuing through the winter [Figs. 6] and [7]. Given the current atmospheric and oceanic conditions, along with model forecasts, the forecaster consensus favors the continuation of weak La Niña conditions through December-February (DJF) 2016-17. At this time, the consensus favors La Niña to be short-lived, with ENSO-neutral favored beyond DJF. La Niña conditions are present and slightly favored to persist (~55% chance) through winter 2016-17 (click CPC/IRI consensus forecast for the chance of each outcome for each 3-month period).

La Niña is likely to affect temperature and precipitation across the United States during the upcoming months (the 3-month seasonal outlook will be updated on Thursday November 17th). Seasonal outlooks generally favor above-average temperatures and below-median precipitation across the southern tier of the United States, and below-average temperatures and above-median precipitation in the northern tier of the United States.

This discussion is a consolidated effort of the National Oceanic and Atmospheric Administration (NOAA), NOAA's National Weather Service, and their funded institutions. Oceanic and atmospheric conditions are updated weekly on the Climate Prediction Center web site (El Niño/La Niña Current Conditions and Expert Discussions). Forecasts are also updated monthly in the Forecast Forum of CPC's Climate Diagnostics Bulletin. Additional perspectives and analysis are also available in an ENSO blog. The next ENSO Diagnostics Discussion is scheduled for 08 December 2016 . To receive an e-mail notification when the monthly ENSO Diagnostic Discussions are released, please send an e-mail message to: [email protected].

[packbacker]

Wish I could see what Nov 83 looked like but will be interesting to see if we get a 2+ year nina like previous strong nino's.  Looks nothing like we saw for 2010/2007/1998.