El Nino / La Nina - Effect on NAO

[lorenzo]

Hi Folks,

My first post on here and look forward to hearing from fellow weather freaks. Well atleast thats what I get called.

My meteorological knowledge is strictly amateur and I enjoy reading these pages and others online esp, the noaa sites.

Can anyone give their thoughts on La Nina / El Nino and the effect it has on our part of the world - it seems that we get drowned with wet weather each time this cycle completes. Also I have wondered about whether this weather system is part of a larger global system and what effect it has on NAO if any. No one has proven a link - but the amount of water El Nino dumps into our hemisphere must do something??

As for our current weather - will the beginning of the Hurricaine season drag all the wet weather out into The Atlantic and mean some SUNSHINE - or will these Hurricaines track back North East and slam into Britain end July / August.

Any thoughts or answers !!

[snowmadchrisuk]

Hi Folks,

My first post on here and look forward to hearing from fellow weather freaks. Well atleast thats what I get called.

My meteorological knowledge is strictly amateur and I enjoy reading these pages and others online esp, the noaa sites.

Can anyone give their thoughts on La Nina / El Nino and the effect it has on our part of the world - it seems that we get drowned with wet weather each time this cycle completes. Also I have wondered about whether this weather system is part of a larger global system and what effect it has on NAO if any. No one has proven a link - but the amount of water El Nino dumps into our hemisphere must do something??

As for our current weather - will the beginning of the Hurricaine season drag all the wet weather out into The Atlantic and mean some SUNSHINE - or will these Hurricaines track back North East and slam into Britain end July / August.

Any thoughts or answers !!

your user name lorenzo is 1 of the names for hurricanes this year. well we all know la nina results n the cooling of the pacific ssts and basicly means places that are uaually dry become even drier and places normally wet become wetter. The effect im intrested in is the effect it has on the uk's winter. more ppn would be greatly appreated by everyone. But even more importantly than that I would like to know what effect it will have on our tempratures. They do say that mid lattitude can have cooler tempratures. 2001 was a snowy year for the uk and 2001 was also the last la nina event. This year la nina was detected starting to build in march and could carry on for up to 12 months but possibly in extremes can carry on upto 2 years. It is also likely to have an efect on the hurricane season as the stronger jet causes more energy into the circulation. Should be an intresting year.

Chris

Edited July 8, 2007 by snowmadchrisuk

[kold weather]

The turth is there probably isn't any really solid evidence to suggest anything. I've done some research on the Arctic Oscillation and La nina and El nino results which surprised me quite a lot. Some people suggested that a negative AO was caused by La nina and hence why La nina has caused this summer to be so poor but instead La nina actually promoted a slightly positive AO on average during the summer. El Nino surprisingly gave a -ve AO signal. As for the NAO, relaly can't say, i may have a little look to see if there is any link or not.

[BrickFielder]

It is generally agreed that la nina gives less upper level wind shear across the atlantic hurricane formation areas meaning that topcial storms have a greater opportunity to develop into hurricanes.

CPC view of Hurricanes and la nina

Climate models suggest that la nina gives warm dry weather over the southern united states which causes the azores/bermuda high to ridge towards that area.

la nina affects.

While the azores high is ridging towards the US. it is not heading our way giving warm settled weather to us. A high pressure ridge over the southern states will also provide a nice avenue for hurricanes so I would expect fewer hurricanes recurving toward the UK although you cannot rule out hurricanes moving up to the east of the azores high from the south.

NAO patterns are mostly independant of la nina and tend to develop as a result of conditions at upper levels at the north pole. Well actually it is the AO which is independant of la nina and the fact that la nina shifts the jet stream north across north america means that the jet stream is also altered across the atlantic and the UK. As the PNA is forced so to a lesser extent is the NAO with the result that there is a tendency towards a positive NAO during la nina events (mild wet winter). The current la nina is fairly weak so we might expect any NAO signal to be overriden by the QBO signal and pressure pattern anomalies across the artic.

NAO La nina link

[lorenzo]

Quality - replies at last - thanks Chris Kold Weather and Brick Fielder - these were the posts I was looking for. Did not know the Azores high affected USA so profoundly, that La Nina alters upper level winds and Hurricaine formation is interesting too.

In regards to AO surely it is positive - wet as hell and trade winds kicking off.. la nina weather already being tracked for its impact perhaps here...

http://nsidc.org/research/projects/Serreze...ntemporary.html

Btw Picked Lorenzo deliberately as a user name because it is one of our storm names this season..

That AMO link is Doctorate level stuff! Brilliant -going to take my novice brain some time to compute all that..

Can anyone do a list of all the different oscillations or is there a good globe graphic of these. Surely they are all interconnected its just a case of statistical modelling to prove it..

So another wet windy winter... seasonal temps above average then a much colder one next year? Whats the main factor in how our winter will unfold?

This report is excellent also especially for SSTs..

http://www.cpc.noaa.gov/products/analysis_...s-fcsts-web.pdf

[Lettucing Gutted]

It looks like Britain just can't win. So a strong La Nina helps mild winter conditions and yet the winter of 2006/2007 had an El Nino.

[kold weather]

A strong La Nina and strong El nino usually does lead to mild condtions but weak-mod El nino/La nina usually don't over-rule other factors, in 2006-2007 it was the super positive AO that killed last witner, not the El nino, indeed it was just about one of the most positive AO's ever in winter, only 1988-89 can match it I believe.

[azores92]

A strong La Nina and strong El nino usually does lead to mild condtions but weak-mod El nino/La nina usually don't over-rule other factors, in 2006-2007 it was the super positive AO that killed last witner, not the El nino, indeed it was just about one of the most positive AO's ever in winter, only 1988-89 can match it I believe.

so really there is nothing to say that el nino or la nina impacts the NAO?!