Sea Surface Temperature - SSTs

[The watcher]

NAO = North Atlantic Oscillation

PDO = Pacific Decadel Oscillation

SST = Sea Surface Temperature

You can find the meanings of a -/+ oceanic state in the learning area of the forum.

[chionomaniac]

Please could someone publish an explanation of what the multitude of 'short hand' metorological letters mean in English - for instance -ve PDO - whats that supposed to mean ?? For a newbie it makes reading and understanding post almost impossible so a little list of 'this is what it means' would make this site even more interesting - thanks !

Hi innov8tion and welcome to the forum.

I am sorry to confuse you with acronyms! Please just ask and I will try and link answers to them so that you can understand the meanings.

To start with PDO http://jisao.washington.edu/pdo/

And for others

http://www.netweather.tv/forum/topic/46150-longer-term-forecasting/

Any others please just say

c

[Snowmad79]

Hi SM79,

Working out how a negative PDO phase may affect a developing El Nino is complex, and I don't think that you can state that a negative PDO base state doesn't have an effect when El Nino conditions have set in. My take on it is that a negative PDO state will be bound to affect an El Nino because they are both antagonistic to each other.

I would suggest that if an El Nino is akin to boiling a pan of water, then, in a negative PDO state, one could suggest that this is akin to continuously adding cold water to that pan. The constant adding of cold water will prevent the pan heating to the same temperature that it would were it not added.

Having said that, the Pacific Ocean profile looks neither like a classic positive nor a classic negative PDO presently.

http://jisao.washing.../pdo/PDO.latest

http://weather.unisy...e/sst_anom.html

As has also been pointed out before, the global SST's are also vastly different to 2006 presently (especially the Atlantic profile) so I don't think we can use that as a good analogue to compare to.

http://weather.unisy...anom-060924.gif

I would also be very cautious about reading too much into any forecast suggesting that El Nino is going to strengthen anywhere beyond the lower end of moderate. These forecasts have an extremely poor verification rate. The recent KW downwelling doesn't seem to have increased the anomaly at the 3.4 region with it remaining at +0.9 today however the full effects of this may not be felt yet.

One way of judging where we feel the El Nino may be heading is by looking at the SOI index.

http://www.bom.gov.a...ssary/soi.shtml

The more negative the SOI, the stronger atmospheric El Nino conditions we are experiencing. Currently this is running at positive values with an average 2.93 for the last 30 days average.

http://www.longpaddo...30DaySOIValues/

This is hardly what is expected of an El Nino state!

If anything it looks like we are heading into an El Nina or perhaps a La Nino! El Nino sea conditions with a La Nina atmospheric state.

c

Ok mate fair point. If im honest I have had to do some trolling on the Southern Oscillation Index and you are totally right how the SOI and Enso are connected and that persistant negative SOI values represent developing El Nino episodes and conditions which was again true leading up the current conditions.

However isnt it also true that the SOI has shown possitive values during some previous El Nino episodes ? and that these would need to remain possitive for some time before we could say what the likely outcome is ?

Not sure if I worded my previous post properly but Im defonatly not saying El nino will strengthen towards strong or that it wont eventually abate and swing towards a La Nina, Im just pointing out that El nino wont simply be "cancelled out" and that it will most likely still reach a moderare level of atleast a 1.1. Similar to the 2006/2007 Moderate Episode. Also wether or not it acheives "Episode" status wont be known for a few months yet anyway.

Craig

Ps. Im no expert as you probably already know, Im just going off what Ive read and learnt from various sites, mainly Noaa.

[Typhoon John]

However isnt it also true that the SOI has shown possitive values during some previous El Nino episodes ? and that these would need to remain possitive for some time before we could say what the likely outcome is ?

The current SOI this September is fairly positive. There's never been a moderate El Nino when the SOI has been so high. But that's not to say it won't happen!

[chionomaniac]

Not sure if I worded my previous post properly but Im defonatly not saying El nino will strengthen towards strong or that it wont eventually abate and swing towards a La Nina, Im just pointing out that El nino wont simply be "cancelled out" and that it will most likely still reach a moderare level of atleast a 1.1. Similar to the 2006/2007 Moderate Episode. Also wether or not it acheives "Episode" status wont be known for a few months yet anyway.

Craig

Ps. Im no expert as you probably already know, Im just going off what Ive read and learnt from various sites, mainly Noaa.

I am no expert either, Craig! I do feel that there are reasons why this El Nino might not reach moderate. The next month or so will be critical to how strong this El Nino will eventually reach.

c

[Typhoon John]

Looking at the Pacific the PDO looks like it could be heading positive with that huge cold anomaly drifting a little South West.

http://weather.unisys.com/surface/sst_anom.html

Although some charts show it better than others.

[Cecil Hogmanay Melchett]

Isn't there a time lag assosiated with el nino la nina? My understanding is the lag is about 3 to 4 months meaning the current state now will effect us in say dec/jan?

Can anyone confirm or dismiss this ?

thanks

[Snowmad79]

The current SOI this September is fairly positive. There's never been a moderate El Nino when the SOI has been so high. But that's not to say it won't happen!

Ok Im with ya there I cant find the data to proove otherwise hehe, The interesting thing ive come across by looking into this further is that the SOI was decently positive from August 2008 until march/april this year. On one hand it didnt stop the current El Nino "conditions" developing on the other it did tie along with Nerutal Enso conditions of last winter which is something new and exiting to me lol.

But is there anything to show this wont swing back the otherway leading to Enso strengthing again in the coming months ?.

These are the sites im reading the info from atm :

SOI

Noaa SOI info ( scroll down page)

Along with various others.

[chionomaniac]

It certainly looks to me that the negative anomaly that has persisted in the mid Atlantic all summer is reducing in intensity. If I remember rightly, we are in a positive AMO phase, so to see a temporary reverse during a positive phase is unusual, but not untypical, .

http://weather.unisys.com/surface/sst_anom.html

However with a positive anomaly setting up East of Iceland, this could lead to Scandinavian trough formation, which would be no bad thing if there was a corresponding pressure rise further west.

[Typhoon John]

Ok Im with ya there I cant find the data to proove otherwise hehe, The interesting thing ive come across by looking into this further is that the SOI was decently positive from August 2008 until march/april this year. On one hand it didnt stop the current El Nino "conditions" developing on the other it did tie along with Nerutal Enso conditions of last winter which is something new and exiting to me lol.

But is there anything to show this wont swing back the otherway leading to Enso strengthing again in the coming months ?.

I don't think the SOI dictates the ENSO state but it does seem to moderate it. So for example, an El Nino is trigged by a combination of things and if the SOI is positive it stifles its development whereas if it is negative it aids its development. Basically I don't see the SOI as the primary driver of ENSO.

ENSO may strengthen in the coming months but I think its too far behind now to reach a moderate peak.

Edited September 27, 2009 by fozi999

[chionomaniac]

Latest SST's are showing that the Atlantic cold area has almost dissipated now that we have entered October. I can hardly say that I am surprised considering that we are in a positive AMO phase.

http://weather.unisys.com/surface/sst_anom.html

We need to keep an eye on the cold pool south of Alaska. If this drifts south then it will modify the El Nino to some extent. There is a lot to keep ones eye on this Autumn which is why anyone making any winter predictions at this point is extremely brave indeed.

c

[SteveB]

What do the experts think to the current state of the oceans.

http://weather.unisy...e/sst_anom.html

Considering this should be the warmest period for the oceans in the Northern hemisphere, it doesn't look to bad. The Atlantic is looking fairly neutral.

Edited October 10, 2009 by SteveB

[Typhoon John]

I'm not going to claim to be an expert but these are my thoughts.

PDO looks fairly neutral.

Atlantic not really chowing any signal yet for NAO but there's still time for it to develop. This map gives a slightly different picture.

http://www.osdpd.noaa.gov/data/sst/anomaly/2009/anomnight.10.8.2009.gif

Look for the cold pool off Newfoundland to expand.

Also of interest is the Peru Current which seems to be doing a great job of mixing out the El Nino and helping to keep it West based.

[Guest North Sea Snow Convection]

I'm not going to claim to be an expert but these are my thoughts.

PDO looks fairly neutral.

Atlantic not really chowing any signal yet for NAO but there's still time for it to develop. This map gives a slightly different picture.

http://www.osdpd.noa...t.10.8.2009.gif

Look for the cold pool off Newfoundland to expand.

Also of interest is the Peru Current which seems to be doing a great job of mixing out the El Nino and helping to keep it West based.

There is some cooling going on to the east - off the coast of Peru. Also the colder waters in the North Pacific have mixed a bit and spread a little further south, which is good to see. As long as that happens that will keep the lid on el nino

Edited October 11, 2009 by North Sea Snow Convection

[snowflakey]

I'm not going to claim to be an expert but these are my thoughts.

PDO looks fairly neutral.

Atlantic not really chowing any signal yet for NAO but there's still time for it to develop. This map gives a slightly different picture.

http://www.osdpd.noaa.gov/data/sst/anomaly/2009/anomnight.10.8.2009.gif

Look for the cold pool off Newfoundland to expand.

Also of interest is the Peru Current which seems to be doing a great job of mixing out the El Nino and helping to keep it West based.

Is it me not reding the maps correctly or are the two SST maps show different results as regards the temps offf the Newfoundland coast. One seems to be positive and the other negative ?

[BLAST FROM THE PAST]

Is it me not reding the maps correctly or are the two SST maps show different results as regards the temps offf the Newfoundland coast. One seems to be positive and the other negative ?

No, that's the NOAA, they have to try and promote 'warmest oceans ever'.

Re El Nino, it has been squeezed and I will post again that i think it has peaked.....watch for a possible drop away during Dec.

BFTP

Edited October 11, 2009 by BLAST FROM THE PAST

[Typhoon John]

But the NOAA map shows the cold pool.

I think it's more to do with the way the maps are generated, with the warm areas being dominant and averaging out the colder area.

[SteveB]

Looking at the latest SST's the North I don't think is looking to bad. Nice to see a negative anom in the Greenland sea, and that extremely positive anom Chukchi sea is dwindling.

http://weather.unisys.com/surface/sst_anom.html

[chionomaniac]

Looking at the latest SST's the North I don't think is looking to bad. Nice to see a negative anom in the Greenland sea, and that extremely positive anom Chukchi sea is dwindling.

http://weather.unisys.com/surface/sst_anom.html

We need to keep a close eye on the Atlantic SST's in the run up to winter. All summer there was a large negative Atlantic anomaly, which looked suggestive of a negative period in the positive AMO phase that we are in. Since the autumn has started we have seen this negative anomaly being replaced by a positive one. Things are shaping up to possibly be hinting at a SST pattern for winter that could encourage a -NAO.

Look at the change in Atlantic SST's over the last month:

September 27th-

October 25th-

I would say that over the last month that we have moved more towards a SST profile of a negative NAO:

Positive NAO:

Negative NAO:

Now I am not suggesting in this post that we are going to have a negative NAO this winter, rather though that if we look at certain building blocks that we would prefer to see in place, then the Atlantic SST are trending in the right direction.

I have seen a lot written on Eastern forum about the PDO state necessary for cold in Eastern USA and there seems to be some conflicting opinions when I look at this state for cold in the UK. One line of thought is that a positive PDO goes hand in hand with a negative NAO and yet I have seen it also suggested that we should be looking for a negative PDO for a more favourable pattern here. I am left wondering which is true. If any one can shed any light on this it would be much appreciated . And how does the PNA fit in around this? Here are the different Pacific anomalies for the positive and negative phases.

When you compare the most recent SST's to this, one can suggest that even though we are in a negative PDO phase, we are seeing a neutral or weakly positive PDO presently as this I suspect has been heavily influenced by the El Nino.

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

The El Nino has increased in strength in the last couple of weeks but seemingly remains strongest on it's western side. This will need carefully monitoring over November as I am sure any strength and amplification of the pacific jet stream will rely on this.

c

[Guest North Sea Snow Convection]

My understanding is that a -PDO is more conduisive for a southerly tracking jet stream along with a +PNA which leads to a bifurcation or splitting of the pacific jet stream rather than straight jet energy across the states which often leads to the corridor of death and the energy going into the northern branch.

Assuming those factors were in place, then the continuing development of the current atlantic profile would bode well for a -NAO (along with nino being as weak and as west based as possible).

Those are the 'ifs' (which remain to be seen) - as i see it anyway.

Someone else might be able to say how true this is.

[chionomaniac]

My understanding is that a -PDO is more conduisive for a southerly tracking jet stream along with a +PNA which leads to a bifurcation or splitting of the pacific jet stream rather than straight jet energy across the states which often leads to the corridor of death and the energy going into the northern branch.

Assuming those factors were in place, then the continuing development of the current atlantic profile would bode well for a -NAO (along with nino being as weak and as west based as possible).

Those are the 'ifs' (which remain to be seen) - as i see it anyway.

Someone else might be able to say how true this is.

Thanks T,

Working out where the resident troughs and ridges would possibly be situated upstream this coming winter is never an easy thing.

[Guest North Sea Snow Convection]

Thanks T,

Working out where the resident troughs and ridges would possibly be situated upstream this coming winter is never an easy thing.

Only thing is, I think I have got the PNA the wrong way around!

It is a -PNA that retracts the Asian/Pacific jet flow westward and splits it in the north pacific

[chionomaniac]

Only thing is, I think I have got the PNA the wrong way around!

It is a -PNA that retracts the Asian/Pacific jet flow westward and splits it in the north pacific

So when you have this Pacific split of the jet stream what happen to each arm as they cross North America?

If the northern arm remains weak and then I assume this can lead to blocking upstream and a more amplified pattern.

[Glacier Point]

West-based Nino events tend to result in a trough down the western Atlantic:

This is just one factor pointing towards a mean trough solution for the western Atlantic right now. Tellingly, Atlantic surface temperatures have started to fall. This reanalysis (change in SSTA) shows a 1 - 2 degree fall over October so far.

I'm thinking this winter is going to be decided by the strength of Siberian High pressure cell and the feedback loops that this generates on the Asian and Pacific Jets.

[Guest North Sea Snow Convection]

So when you have this Pacific split of the jet stream what happen to each arm as they cross North America?

If the northern arm remains weak and then I assume this can lead to blocking upstream and a more amplified pattern.

El nino predisposes a +PNA with high pressure belt around Hawaii and jet flow goes around the top.

Last winter, under the nina conditions we saw a far amount of blocking over the Canadian arctic and this assisted a -PNA with the jet splitting and being squeezed further south. As we saw with the NW-SE tilted jet stream in the first part of the winter quite a bit and with split flow sending some energy into the STJ and a relative absence of the corridor of death..

So more reasons it seems, to want el nino to wane