How will this effect the snow fall in Scotland?

"How will this effect the snow fall in Scotland?"

It almost certainly won't, but any cold periods (or warm periods, or dry periods, or wet periods) will be attributed to El Nino by the I-told-you-so long range 'forecasters'.

The only (generally) predictable effects are local to the middle Americas, and elsewhere downstream it's a lottery. At our longitude (roughly half way around the world from the El Nino/La Nina source), its effects are so diffuse that it's impossible to distinguish between correlation and chance, even at more middling latitudes like the Euro Alps. For Scotland's latitude and longitude, seeing a correlation between weather patterns and El Nino/La Nina is the domain of hocus pocus practising, long range weather forecasters pushing sensationalist stories to newspapers. You'd have as much luck using tea leaves and crystal balls to predict next winter's conditions as you would by factoring in El Nino. There are plenty of resources on the internet collecting stats for European winters with data for EN/LN too, and they reveal nothing.

Here ya go ... [www.metoffice.gov.uk]

El Nino gets all the headlines as result of the impact it has on North and South American weather. However it is the North Atlantic Oscillation (NAO) that has bigger impact on European weather ?

The NAO is basically an index recording seasonal pressure difference between the stable Azores high and Icelandic low in northern Europe. An exceptionally -ve NAO probably played a big role in the unusually cold 2010 winter we experienced in Scotland ?

Several studies have claimed that melting sea ice in the arctic means that Europe is more likely to experience northerly, rather than prevalent Atlantic westerly, weather systems (i.e -ve NAO). Which of course means a higher chance of colder winters, in the short term at least.

[en.wikipedia.org]



Edited 2 times. Last edit at 10.13hrs Wed 20 May 15 by Doug_Bryce.

The problem is NAO is hard to forecast and has some marked differences to other climatic variables like ENSO. NAO is a bt like say the avaerage temperature in aviemore. If that is below average then there is more likely to be snow in the cairngorms etc. That gives a good corelation but it is hard to rpedict if the temeprature in Aviemore is above or below average.

NAO can flip positive or negative from 1 day to the next because it is essentially a measurment of weather rather than any long term stable climatic factor like ENSO.

^ Basically you are saying that European weather is dominated by westerly systems from the Atlantic, and thus is generally mobile, variable and hard to forecast long term. Certainly this is true.

However : in 2010 (for example) there was a sustained and unusual -ve NAO shift which resulted in persistent northerly and easterly weather systems. The end result was the coldest Scottish winter in 30 years. Several studies have suggested melting arctic sea ice could raise sea temperatures and make these scenarios more likely to occur in the near future.

El Nino is fundamentally a Pacific weather phenomena, and thus any impact on Scotland will be a secondary effect. However there probably is some interaction as the Pacific ocean is the planets biggest volume of water.

[www.haggistrap.co.uk]



Edited 1 times. Last edit at 16.20hrs Thu 21 May 15 by Doug_Bryce.

In 2010 some not well understood climatic conditons occured which caused the frequent occurence of northerly and easterly systems. This anomoly was recorded as a strongly negative NAO, hwoever the negative NAO didn't cause the anomolous weather systems.

this is what is different with things like ENSO, with ENSo there is a measureable difference in sea surface temperatures and resutling wind patterns. The ocean conditons is what causes all the associated efects of El Nino and La Nina.
Ocean temepratures are fairly stable so the causal factor can stay in effect over a peridos of many months.

With NAO we don't have any underlying stable ocean change that would pesistently effectthe NW eiropean climate. As you point out that there is hitns that colder conditons in the north atlantic can have an influence but these are far less predictable than ENSO,


I agree that ENSO is relatively worthless as a predictor for scottish conditons, and looking at historic correlatios NAO is fairly robust. However, the abiltiy to forecast NAO is very poor, moreover, even with the NAO strongly negative 1 week the next is can be strongly positive. With ENSO, weekly changes are much more subtle and thus the associayed anomlaies more stable, whcih si why in parts of the world where ENSO has an effect it's forecast can be very importnt and reliable.

Th difference is fairly subtle. If we coudl predict NAO accurately then it would ahve the same predicit power as ENSO but as it is negative NAO is a bt like saying when the weatehr comes from the N and E it will be colder than average which is not surprisng. We want to know why the weather would be mor eliely to come from there but NAO doesnt really explain why.




Edited 1 times. Last edit at 22.41hrs Fri 22 May 15 by timstirling.

^ Remember that predicting El Nino for long term weather forecasts is a relative modern idea (last 20 years or so). Previously we simply didn't have enough weather data from buoys or satellites etc.

Certainly the NAO is lesser understood. The Atlantic is also a smaller volume of generally cold water, and mobile weather systems : which makes things tricky. However meteorologists are now developing a much better understanding of how it can modeled and used for longer term weather predictions.



[www.metoffice.gov.uk]



Edited 1 times. Last edit at 08.16hrs Mon 25 May 15 by Doug_Bryce.