Technical La Nina 2017/18

rocketboy

One of Us
Ski Pass
Sep 9, 2010
3,130
5,549
363
Gerroa
And here comes the rain ....

poama.nino34.png


The ENSO wrap up for Sep 24 is now posted
http://www.bom.gov.au/climate/enso/

Tropical Pacific Ocean cooling expected to continue

The El Niño–Southern Oscillation (ENSO) is neutral. However, sea surface temperatures (SSTs) have cooled in the central to eastern tropical Pacific since mid-winter. These SSTs are currently cooler than average but within the neutral range. Waters beneath the surface are also slightly cooler than average. Other indicators of ENSO, such as the Southern Oscillation Index (SOI) and trade winds, also remain at neutral levels.

All international climate models surveyed by the Bureau suggest further cooling of the tropical Pacific Ocean is likely. Five of the eight models suggest SSTs will cool to La Niña thresholds by December 2017, but only four maintain these values for long enough to be classified as a La Niña event.

While unusual, it is not unheard of to see La Niña develop this late in the year—the Bureau will keep a close watch for further, or sustained, cooling of the equatorial Pacific. Of the late-developing La Niña events, their effect on summer rainfall has been mixed, with some leading to widespread wet conditions across eastern Australia, and others having minimal effect.

The Indian Ocean Dipole (IOD) is neutral and the model consensus suggests it will remain so. Three of the six climate models surveyed suggest positive IOD thresholds may be reached during spring, but it may now be too late to become an event. If a positive IOD eventuated it would be short-lived, as events typically decay by December.

The dial remains at neutral.
 
Last edited:

Jellybeans

Part of the Furniture
Ski Pass
Aug 24, 2015
13,027
21,461
813
Canberra
IMG_2146.GIF

Most models are going for Borderline La Niña or Cool Neutral, with CFS being the outlier for a stronger La Niña.
IMG_2148.GIF

This is a history of ENSO predictions, showing the obvious outliers that are never achieved in reality (black line).

The 30 day SOI is +6.8, 90 Day SOI being +3.3
 

POW Hungry

Old n' Crusty
Moderator
Ski Pass
May 28, 2000
23,001
36,746
1,063
Eastern Burbs of Sydney
I think there will be a reluctance to adjust the status based the cooling SST's, the other climate drivers (SOI & IOD) have remained quite neutral and cloudiness in the average range.
 
  • Like
Reactions: Kletterer

Kletterer

Thredbo Doughnut Tragic
Moderator
Nov 26, 2014
21,853
26,130
1,063
Canberra
I think there will be a reluctance to adjust the status based the cooling SST's, the other climate drivers (SOI & IOD) have remained quite neutral and cloudiness in the average range.
Whats your take on the SAM/ South Tropic Ridge situation/forecast ?
 

Hermon

One of Us
Aug 24, 2008
2,332
1,651
363
Well the AAO is strongly +ve at the present. We'll probably see a fair bit of Pacific Ocean tropical air drift inland from the NE before too long...
 

Jellybeans

Part of the Furniture
Ski Pass
Aug 24, 2015
13,027
21,461
813
Canberra
Long Range GFS suggests the Subtropical High moves north over Southern Australia.

In other news, SH Polar Vortex still decaying....
IMG_2150.PNG

Once it's finished, the STR will go into place IMO.
 

POW Hungry

Old n' Crusty
Moderator
Ski Pass
May 28, 2000
23,001
36,746
1,063
Eastern Burbs of Sydney
Whats your take on the SAM/ South Tropic Ridge situation/forecast ?
I was looking at the Southern PV last night and we're seeing solid + anoms (at 10mb PV level) which is suggestive to me it's got a bit left in it, the problem is the sub-trop ridge will only strengthen as it re-establishes itself with heating through the sub trops - namely over Aus. Whether that means we'll see an increase in block patterns and cut off lows, I am not too sure but it does appear the PV will have an uphill battle against the transition into warmer SH patterns. I guess this partly why climate models suggest a decline in the SAM/AAO value.

Sorry, it's not a definitive answer/opinion... If there's one area I learn the most on it's the climate drivers, the complexity of influences is massive and I struggle to keep up with a lot of it most of the time.
IMG_7202.GIF
 
  • Like
Reactions: Kletterer

Jellybeans

Part of the Furniture
Ski Pass
Aug 24, 2015
13,027
21,461
813
Canberra
the PV has an uphill battle against the transition into warmer SH patterns
Yeah, you can kind of see it looking on the EC 10mb SH charts on AccuProWx. The vortex is dying as the stratospheric hot anomaly overpowers the vortex as it weakens. I reckon it will all be gone by the end of October/early November.

GIF of the SH polar vortex on EC.
IMG_2164.GIF

If it doesn't work
 

MarkV

One of Us
Ski Pass
May 4, 2016
645
1,235
263
How will an eruption of Mount Agung be likely to effect any potential La Nina?
 
  • Like
Reactions: malas1

POW Hungry

Old n' Crusty
Moderator
Ski Pass
May 28, 2000
23,001
36,746
1,063
Eastern Burbs of Sydney
Yeah, you can kind of see it looking on the EC 10mb SH charts on AccuProWx. The vortex is dying as the stratospheric hot anomaly overpowers the vortex as it dies. I reckon it will all be gone by the end of October/early November.

GIF of the SH polar vortex on EC.
IMG_2164.GIF

If it doesn't work
I think you may have your wires crossed, the PV doesn't 'die', it's a persistent upper level low. It simply strengthens and weakens. Generally speaking, in winter it's strengthened, in summer it's weakened.
Right now, late-winter/early spring it's at it's weakest (as 'normal'), hence why we're seeing the models throw up cold snaps and cut-off scenarios.

But yes, as EC models it, it is running a little 'hot'.
pole10_sh.gif
 

Jellybeans

Part of the Furniture
Ski Pass
Aug 24, 2015
13,027
21,461
813
Canberra
I think you may have your wires crossed, the PV doesn't 'die', it's a persistent upper level low. It simply strengthens and weakens. Generally speaking, in winter it's strengthened, in summer it's weakened.
Right now, late-winter/early spring it's at it's weakest (as 'normal'), hence why we're seeing the models throw up cold snaps and cut-off scenarios.

But yes, as EC models it, it is running a little 'hot'.
pole10_sh.gif
I was probably exaggerating a bit, but I think my point is still there. The STR will fall into 'summer mode' when the polar vortex weakens fully.
 

Jellybeans

Part of the Furniture
Ski Pass
Aug 24, 2015
13,027
21,461
813
Canberra
How will an eruption of Mount Agung be likely to effect any potential La Nina?
I am not quite sure about that, but if it does what it did in 1964 (pump millions of tons of sulfur compounds into the stratosphere), global temperatures will take somewhat of a dive for a year or two. Cooler weather = more snow.
 
  • Like
Reactions: malas1 and MarkV

Hermon

One of Us
Aug 24, 2008
2,332
1,651
363
I think you may have your wires crossed, the PV doesn't 'die', it's a persistent upper level low. It simply strengthens and weakens. Generally speaking, in winter it's strengthened, in summer it's weakened.
Right now, late-winter/early spring it's at it's weakest (as 'normal'), hence why we're seeing the models throw up cold snaps and cut-off scenarios.

But yes, as EC models it, it is running a little 'hot'.
pole10_sh.gif
That's got me wondering whether the recent solar flares had an influence in the recent spike in temps?
 

Jani Makaraiinen

Addicted
Aug 5, 2017
110
152
113
I am not quite sure about that, but if it does what it did in 1964 (pump millions of tons of sulfur compounds into the stratosphere), global temperatures will take somewhat of a dive for a year or two. Cooler weather = more snow.

Not necessarily , more likely maybe.
 

Jellybeans

Part of the Furniture
Ski Pass
Aug 24, 2015
13,027
21,461
813
Canberra
I am not quite sure about that, but if it does what it did in 1964 (pump millions of tons of sulfur compounds into the stratosphere), global temperatures will take somewhat of a dive for a year or two. Cooler weather = more snow.
Actually ABC out of the blue just did a story on it.

Back to the ENSO topic....
EC Seasonal prediction for SSTs in November. You can see the cooler SSTAs in the Niño region.
IMG_2167.PNG


IMG_2168.PNG

All gone by March though....
 

Rush

Pool Room
Jul 26, 2000
45,291
13,663
1,525
Most climate models predict NINO 3.4 exceeding La Nina thresholds by December, but most of these models predict a return to neutral levels by February.

It's very rare for La Nina events to initiate during the southern hemisphere summer.

The NOAA dynamic model is an outlier compared to other model forecasts for NINO 3.4 anomalies in the next few months.
 

Kletterer

Thredbo Doughnut Tragic
Moderator
Nov 26, 2014
21,853
26,130
1,063
Canberra
You are correct it was apparently proven many years ago QBO has no affect on enso.
Around 2010/ 2011 ? Just been catching up on some reading and as i am still a rookie jumped the gun a little. :oops: At least its weather and not porn i am looking at.:D
 

J_-W_-X

Hard Yards
Sep 28, 2017
176
212
43
Around 2010/ 2011 ? Just been catching up on some reading and as i am still a rookie jumped the gun a little. :oops: At least its weather and not porn i am looking at.:D
You likely find looking @ sexy girly models more interesting than strat winds filtering
down into the pacific..models :)
 
  • Like
Reactions: Jellybeans

Falls expat

One of Us
Jul 12, 2000
2,922
219
213
London
It amazes me how slow agencies like BOM and NOAA are at predicting the onset of a La Nina. The fact is we have been in a La Nina pattern since last spring.

Trade winds have been elevated, OLR is high and a building deep cold sea temp anomaly pool. 150m Sea temp anoms are now -3 deg C below normal. Upper Ocean heat anoms are already stronger than this time last year.

We are not only going to see a La Nina, but I predict it will reach moderate status at -1 or lower. I would expect a cloudier, wetter and cooler eastern coast of Australia on average this summer due to enhanced easterly trade winds. However, as is often the case this means severe heat builds up in central Australia. If this gets a chance to break out it will bring a short lived but severe heatwave probably in Jan or Feb.
heat-last-year.gif
polr_c.gif
wkteq_xz.gif
 

Rush

Pool Room
Jul 26, 2000
45,291
13,663
1,525
It amazes me how slow agencies like BOM and NOAA are at predicting the onset of a La Nina. The fact is we have been in a La Nina pattern since last spring.

Trade winds have been elevated, OLR is high and a building deep cold sea temp anomaly pool. 150m Sea temp anoms are now -3 deg C below normal. Upper Ocean heat anoms are already stronger than this time last year.

We are not only going to see a La Nina, but I predict it will reach moderate status at -1 or lower. I would expect a cloudier, wetter and cooler eastern coast of Australia on average this summer due to enhanced easterly trade winds. However, as is often the case this means severe heat builds up in central Australia. If this gets a chance to break out it will bring a short lived but severe heatwave probably in Jan or Feb.
heat-last-year.gif
polr_c.gif
wkteq_xz.gif
Big call. Let's see how you go in February. BTW 'big agencies' can't flip flop and declare ENSO events at the drop of a hat. There are innumerable actions that are set in motion within the public and private sectors once a La Nina or El Nino is declared. You build better trust with your stakeholders w.r.t. dealing with uncertainty and risk management if you don't flip-flop and change your mind everyone month.

NINO3.4 is back to neutral at the moment.
 

J_-W_-X

Hard Yards
Sep 28, 2017
176
212
43
It amazes me how slow agencies like BOM and NOAA are at predicting the onset of a La Nina. The fact is we have been in a La Nina pattern since last spring.

Trade winds have been elevated, OLR is high and a building deep cold sea temp anomaly pool. 150m Sea temp anoms are now -3 deg C below normal. Upper Ocean heat anoms are already stronger than this time last year.

We are not only going to see a La Nina, but I predict it will reach moderate status at -1 or lower. I would expect a cloudier, wetter and cooler eastern coast of Australia on average this summer due to enhanced easterly trade winds. However, as is often the case this means severe heat builds up in central Australia. If this gets a chance to break out it will bring a short lived but severe heatwave probably in Jan or Feb.
heat-last-year.gif
polr_c.gif
wkteq_xz.gif

And with all that above there is still warmer anoms being sampled.

H2wDJqF.png


Cdas is not always reliable data. Its always a wise choice to match it against
other sources. It does appear to be on par atm with proprietary data graphic below.
3.4....... 02.


uTGInlU.png
 

Falls expat

One of Us
Jul 12, 2000
2,922
219
213
London
Big call. Let's see how you go in February. BTW 'big agencies' can't flip flop and declare ENSO events at the drop of a hat. There are innumerable actions that are set in motion within the public and private sectors once a La Nina or El Nino is declared. You build better trust with your stakeholders w.r.t. dealing with uncertainty and risk management if you don't flip-flop and change your mind everyone month.

NINO3.4 is back to neutral at the moment.

All I am saying is observations support the current neutral weak La Nina to build into a weak to moderate La Nina. Deep SSTs are 3 deg below normal, Upper ocean heat content is cooler than last year already, trade winds are above normal basin wide, the global patterns are adopting a La Nina like zonal shape with enhanced subtropical highs and strong westerly Jets. Why on earth is NOAA saying there is only a 55-60% chance of La Nina forming when we have already seen SST anoms reaching La Nina levels in relevant regions? Last year there was residual warmth in the western basin which broke out as a kelvin wave. This year there is little evidence of this.

Queensland is about see it's first tradewind induced wet event over the coming week (week beginning 16 Oct 2017) with widespread 100+ mm rainfall. This fits in well with the type of pattern that eastern Australia sees in a neutral or La Nina like Pacific SST pattern.

pme1to8.png

Odds are, the east coast of Australia is in for a coolish, fairly wet summer period with the odd severe heatwave breaking out from interior Australia during short periods when the trades shut down.
 

Hermon

One of Us
Aug 24, 2008
2,332
1,651
363
MJO gonna move very fast:
NCPE_phase_21m_small.gif


Apparently a similar thing happened in late-1985. (I remember the Summer of 1985-86 being a non-Summer in Central Vic).
 

J_-W_-X

Hard Yards
Sep 28, 2017
176
212
43
FYI.
Convectively coupled kelvin waves travel fast, the mjo does not and never will.

Your more than welcome to prove me wrong.
 

rocketboy

One of Us
Ski Pass
Sep 9, 2010
3,130
5,549
363
Gerroa
http://iri.columbia.edu/our-expertise/climate/forecasts/enso/current/

>>In mid-October 2017, the tropical Pacific remained in an ENSO-neutral state but near the borderline of weak La Niña, as SSTs in the east-central tropical Pacific have cooled to the threshold for La Niña and the atmosphere has also shown patterns suggestive of near-La Niña conditions. The collection of latest ENSO prediction models indicates weak La Niña as a likely scenario during Northern Hemisphere fall and winter. The official CPC/IRI outlook favors La Niña development, and carries a La Niña watch.<<
 

Jellybeans

Part of the Furniture
Ski Pass
Aug 24, 2015
13,027
21,461
813
Canberra
Yeah I am liking a weak or borderline La Nina over the next few months. The seasonal models/outlooks for the Northern winter seem to be based off a typical La Nina winter. I am waiting for Siberian Snow Cover and North Pacific SSTAs, as well as a variety of other factors, before I make my punt. I might be making another preliminary outlook tomorrow though.
 
  • Like
Reactions: Claude Cat

J_-W_-X

Hard Yards
Sep 28, 2017
176
212
43
The thing with this is its happening now. You are living it. Same as when
el nino come around. Its just a formality as to when the trigger is pulled officially..
 

Jellybeans

Part of the Furniture
Ski Pass
Aug 24, 2015
13,027
21,461
813
Canberra
The thing with this is its happening now. You are living it. Same as when
el nino come around. Its just a formality as to when the trigger is pulled officially..
Wait do you mean we are in a La Niña right now? Atmospheric and oceanic measures now align, but have only done so for a few days. But we are kinda in a La Niña, just not quite a long term one. We will soon find out about the latter.
 
  • Like
Reactions: The Plowking

J_-W_-X

Hard Yards
Sep 28, 2017
176
212
43
Been busy tracking a monster.

Its well known the atmosphere has been nina in the epac since
last season. 3.4 has tanked below 0.8 on quite a few occasions
this current tanking is nothing new. What makes you think the
coupling only occurred over the past few days?.

The sst's never just dropped across the enso region's this week.
as you know.

The slope of the thermocline has been a little odd but does
that justify anything really. in making a call given the sst.

Its my opinion we are in a nina now.

Just because the BOM don't agree atm don't mean everyone else is wrong.

If you buy everything you read on twitter you likely will get egg on your
face 5 times outta ten.

The classic was the elnino coming back because 1.2 was hot that sucked
many in who don't have clue how enso works. As we know alot of misinformed
did RUSH in with that ridiculous forecast.


Now can you pl's post why you believe the coupling was only a few days
ago. I'm always eager to learn something new. And you are one of the very
few on here that i do like J and i do read your posts. So i'm not being a prick.
:)
 
Last edited:

Jellybeans

Part of the Furniture
Ski Pass
Aug 24, 2015
13,027
21,461
813
Canberra
Been busy tracking a monster.

Its well known the atmosphere has been nina in the epac since
last season. 3.4 has tanked below 0.8 on quite a few occasions
this current tanking is nothing new. What makes you think the
coupling only occurred over the past few days?.

The sst's never just dropped across the enso region's this week.
as you know.

The slope of the thermocline has been a little odd but does
that justify anything really. in making a call given the sst.

Its my opinion we are in a nina now.

Just because the BOM don't agree atm don't mean everyone else is wrong.

If you buy everything you read on twitter you likely will get egg on your
5 times outta ten.

The classic was the elnino coming back because 1.2 was hot that sucked
many in who don't have clue how enso works. As we know alot of misinformed
did RUSH in with that ridiculous forecast.


Now can you pl's post why you believe the coupling was only a few days
ago. I'm always eager to learn something new. And you are one of the very
few on here that i do like J and i do read your posts. So i'm not being a prick.
:)
Fair enough, Lan is pretty big. I haven't been posting there, but all your posts about Lan have been excellent.

Yep agree, atmosphere has been Niña for a while.
IMG_2546.PNG

We have been down to Niña ocean levels once. And then back to neutral. Now tanked to Niña levels. So IMO we have only been in coupled Niña for a few days, because we were in neutral mode before. Hopefully we stay in La Niña for a while.

Thanks, but I think I learn way more from you, than the other way.

The other day I went back on WZ forums, and there was a guy still rambling on about an Warming and no Niña. He was predicting a strong Niño for summer just a few months ago :headbang: Lots of people got sucked in by that Niño 1+2 warming.

I like Twitter, lots of interesting people there. But I know there's a load of crap thrown around there too.
 
  • Like
Reactions: J_-W_-X

Rush

Pool Room
Jul 26, 2000
45,291
13,663
1,525
Moderator's comment:
##### Deleted
 
Last edited by a moderator:
Remove ads with a
Ski Pass