Sea Surface Temperatures

[summer blizzard]

Question: why does La Nina seem to last longer than El Nino?

For instance there was a La Nina that lasted from mid 1973 to mid 1976 but you won't find an El Nino of that length

http://www.esrl.noaa.gov/psd/enso/mei/table.html

I would say that 1990-1994 was a comparable period although some monthly values were neutral.

[John S2]

Question: why does La Nina seem to last longer than El Nino?

For instance there was a La Nina that lasted from mid 1973 to mid 1976 but you won't find an El Nino of that length

La Nina appears to be a more stable pattern than El Nino. I suspect this is because La Nina is an enhancement of normal [ie ENSO neutral] conditions, El Nino is a reversal of normal.

[Weather-history]

http://www.esrl.noaa.../mei/table.html

I would say that 1990-1994 was a comparable period although some monthly values were neutral.

I was looking at this site and you can see La Nina has more periods that reach below -0,5 consecutively for longer than El Nino has 0.5 and above

http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/ensostuff/ensoyears.shtml

La Nina appears to be a more stable pattern than El Nino. I suspect this is because La Nina is an enhancement of normal [ie ENSO neutral] conditions, El Nino is a reversal of normal.

Thanks for your reply, it looks as though that might be the case.

[summer blizzard]

Very nice Atlantic tripole developing along with the very -PDO Pacific signature.

Both of these to me indicate that a very good pattern could develop at some point in late December if the Atlantic tripole carries on developing.

[kold weather]

Question: why does La Nina seem to last longer than El Nino?

For instance there was a La Nina that lasted from mid 1973 to mid 1976 but you won't find an El Nino of that length

Seems tome that El Nino tend to be snap and intense type situations whilst La Nina's tend to be more stable and long lasting, but not as intense over several months as El nino's. It does seem like La Nina's do more often develop in multi-year situations whilst El nino's never seem able to sustain the feedback processes required for a multi-year event.

I've noticed a decent number of El nino's in the past going above say 1.3-1.5C, but

[summer blizzard]

Well the Pacific looks pretty good however that is a definite Atlantic Trough signal.

[kold weather]

La Nina still flirting with moderate strength at the moment, the weeklies coming in around -0.9C and -1C so we are right on the cusp if this continues for any length of time.

[saintssupporter]

[karyo]

La Nina still flirting with moderate strength at the moment, the weeklies coming in around -0.9C and -1C so we are right on the cusp if this continues for any length of time.

It is expected to weaken from now on so I doubt it.

Karyo

[Weather-history]

What's the latest analysis?

[summer blizzard]

http://weather.unisys.com/surface/sst_anom_new.gif

Looks fairly good in the Pacific with a strong -PDO signal coupled with La Nina, so a generally weak Pacific Jest Stream.

Atlantic signal could be better although i would say that the signal supports high pressure off Newfoundland and a low pressure over the west of Europe (lower than average pressure for Spain, France and the UK).

To sum up, good Pacific signal, fairly good Atlantic signal.

Also, i do not fully understand the MJO but in relation to sea surface temperature anomalies would i be right in saying that tropical convection would be least favored near Indonesia, most favored over the La Nina anomalies and neutral in the Atlantic.

[summer blizzard]

Poorer signal in the Pacific in my opinion with La Nina beginning to weaken and a higher thermal gradient going into the western USA.

Signal in the Atlantic looks mixed with a lot of blocking in the west and over the Azores although if heights lower in the Mediterranean or build over Greenland it could be favorable.

I would say that the last ten days of February based off this would likely be fairly cool still but with troughing close to the south of the UK so quite wet.

[summer blizzard]

Stronger -PDO signal in the Pacific, La Nina totally gone in the east.

[karyo]

Stronger -PDO signal in the Pacific, La Nina totally gone in the east.

Out of interest, what is the forecast for the floowing months/rest of the year?

Can we expect an El nino or neutral values?

Karyo

[summer blizzard]

Out of interest, what is the forecast for the floowing months/rest of the year?

Can we expect an El nino or neutral values?

Karyo

The models seem to be headed positive with some going for an El Nino although they are not known for accuracy.

Looking at the analogues then other than 2012 the only other years which saw a January value of -1 or greater are 2011, 2008, 2000, 1999, 1989, 1976, 1974, 1971, 1962, 1956, 1951, 1950 so twelve years in total. Of those, only five recorded recorded positive MEI values that year and only one recorded an MEI value of +1.

Given the analogues and the fact that a -QBO statistically correlates with La Nina then i would say that while there is a chance of a neutral/weak El Nino, there greater likely-hood is that we will continue to see a neutral/weak La Nina.

[Jack Wales]

Interesting thoughts SB, the models were all going for another La-nina summer but the apparent dissapation of ENSO -ve anomolies in the pacific seem to have taken them all by surprise. If you look at the current SST profile, I'd say that only the Nino4 region is still enso -ve with the other regions either displaying neutral or even +ve anomolies in region1/2...

The live daily chart seems to continue the trend...

http://weather.unisys.com/surface/sfc_daily.php?plot=ssa&inv=0&t=cur&expanddiv=hide_bar

Which also seems to be well supported by the sub surface pattern (notice from the time lapse the rapid swing from of -'ve to +'ve anaomolies)...

http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso_update/wkxzteq.shtml

As you say it would be unusual to see an El Nino in tandem with an e'ly QBO but the current pattern shift at least gives me some hope that all may not be lost for this summer :-)

[Interitus]

Poorer signal in the Pacific in my opinion with La Nina beginning to weaken and a higher thermal gradient going into the western USA.

Signal in the Atlantic looks mixed with a lot of blocking in the west and over the Azores although if heights lower in the Mediterranean or build over Greenland it could be favorable.

I would say that the last ten days of February based off this would likely be fairly cool still but with troughing close to the south of the UK so quite wet.

This method needs a bit of work.

[johnholmes]

This method needs a bit of work.

and the purpose of your post other than to adopt a critical attitude is?

[Interitus]

and the purpose of your post other than to adopt a critical attitude is?

Sorry, it's not sniping, I am encouraging reflection and reassessment, that is how we learn and improve.

[summer blizzard]

It is fine, it was indeed wrong although it has been correct at times.

The problem is that it may be easy to pick out large features but trying to decide which synoptic it will yield near the UK is much harder.

[summer blizzard]

[Lettucing Gutted]

Does the recent sst anomaly chart point to a cold North-Beasterly reload after the Easter mild period?

Edited April 5, 2012 by Craig Evans

[summer blizzard]

If anything i would say that the signal is for something close to March again.

Perhaps the signal is being overridden by the stratosphere.

[johnholmes]

There is an interesting article on the Met web site about some research they have done on the Atlantic sea temperatures being affected by some man made and natural emissions.

[cooling climate]

If anything i would say that the signal is for something close to March again.

Perhaps the signal is being overridden by the stratosphere.

I think this April will be nothing like March regardless of what the sst's look

like. Over the years I have become convinced that our weather is dominated

by much bigger forcings and teleconnections than the sst's of the Atlantic.

The Atlantic sst's are a symtom of the synoptics and not a cause of them.