Met Office winter NAO forecast...

[NorthYorksWeather]

The PDO (Pacific Decadel occilation) has a large infuence on our weather, when not at neutral values, it esentially dictates the state of the PNA with a 70% correlation between the two and also to a lesser degree the AO, with a 30% correlation, this is a positive correlation, meaning that if the PDO is negative then the PNA will be encouraged to be negative as well rather than a negative correlation which would mean that the PNA would be encouraged to go positive.

A negative PDO will typically see the following anomoly patttern on a sea surface temperature anomoly chart...

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

As you can see, a negative PDO would typically favour a split Pacific Jet Stream and Alaskan Trough.

As well as having another positive correlation with the ENSO state, it can aid in the development or hindrance of developing ENSO events.

Seen as though i am expecting near neutral conditions and La Nina looks only to be a weak affair, giving only a slight bias towards a negative PNA and AO, i think that the QBO will be the most important teleconnection this winter, giving a fairly large bias towards a negative AO.

and a negative AO should hopefully lead toa cold winter, thanks for the info, although i do not understand every word im learning gradually, vizzy

[beng]

http://www.easternuswx.com/bb/index.php?showtopic=135457

Kold posted the above link on Two - hope he doesn't mind me linking to it here too. I think it gives a decent explanation of how the SSTs in May can impact on the NAO the following Winter. Most people on here will be pleased to note that the methodology described indicates (at this stage) a fairly potent negative NAO signal for the coming winter.

[Anti-Mild]

http://www.easternuswx.com/bb/index.php?showtopic=135457

Kold posted the above link on Two - hope he doesn't mind me linking to it here too. I think it gives a decent explanation of how the SSTs in May can impact on the NAO the following Winter. Most people on here will be pleased to note that the methodology described indicates (at this stage) a fairly potent negative NAO signal for the coming winter.

Thanks for that link beng, interesting stuff!

It'll also be interesting to see if the MetO interpret the data in the same way and give out a cold winter forecast. Although it should be noted that even though they have got it right in recent years it doesn't mean they will continue in that trend.

After saying all that, at this very early stage, it does look positive.

[Glacier Point]

http://www.easternuswx.com/bb/index.php?showtopic=135457

Kold posted the above link on Two - hope he doesn't mind me linking to it here too. I think it gives a decent explanation of how the SSTs in May can impact on the NAO the following Winter. Most people on here will be pleased to note that the methodology described indicates (at this stage) a fairly potent negative NAO signal for the coming winter.

Chuck's method places this May's projection in third place of the all time winter -NAOs, not far behind that year that shall not be named....

One thing the method does not address however is the impact of the AO on the NAO, and, as we know from bitter experience, we need both the NAO and AO in tandem to sustain the desired synoptics. I would view next winter as being a possible re-run of 2005/6 at this stage - certainly the overall context with the solar flux, NAO signals, likley La Nina and easterly QBO pretty much auguer well for cold outbreaks.

[beng]

Very good point GP about the AO it's worth noting that AGW theory predicts that the stratosphere should cool as more heat is trapped in the troposphere which doesn't bode well for negative NAO winters in the future (assuming that the theory holds true). The Arctic Sea ice situation may also have some impact too.

At least this winter we shouldn't have an El Nino and Westerly QBO though. Fingers crossed for a fairly neutral enso this winter:) I'll hope for something a bit better than 05/06 - it wasn't that negative really and overall the Atlantic looks a bit cooler this year and the Pacific has a better signal too.

http://www.metoffice.gov.uk/research/seaso.../nao/index.html

Edited June 8, 2007 by beng

[BLAST FROM THE PAST]

I have a sneaky feeling that this will become a busy and popular thread if the signals remain

BFTP

[tinybill]

nice reading if you take any noticeof the up and coming hurricane season which is thoiught to be more attive this year and 3/4 of that come our way ,with all the talk of a heatwave this summer i got a horrible felling that with the ex, Pacific ,alantic. weather we could very easy have a higher then normal rain fall , not with the weeks of hot and dry summer weather some whants!!

[karyo]

I have a sneaky feeling that this will become a busy and popular thread if the signals remain

BFTP

I really hope so. Something to help me (and other winter lovers) through the summer months.

Seriously though, as positive things may look now, we need to be cautious because I remember many positive signals and winter forecasts that went disappointly wrong!

On the other hand, we shouldn't see another winter like 2006/7 in a hurry - even with climate change.

Karyo

[kold weather]

By the way its interesting to note that the MEI has risen again, now upto 0.179. This is indicating that La Nina may be a little while off yet still which will obviously make a difference. It also makes it less likely to have mod-strong La Nina and its all because of those temps in the western part of the Pacific which is proving quite stubborn to come below average. Worth noting there was similar signals during Spring 2005 in the eastern side of the Pacific and those died away quite readily during May-July...though this time I don't think that will happened given the areas a little colder then back then in that region of the world and we were borderline La Nina during the 05-06 winter.

As for tropical cyclones---I've said so many time sin the past that these features can make and break summers depending on the exact tracks but while they can lead to unsettled weather usually because of their tracks and the warmth they contain in there circulation they do generally give above average temps. However some years tropical cyclones can re-enforce very good set-ups...for example the summer of 95 was very hot here but also had a very active hurricane season (3rd most active ever!) yet that was dry and hot for most of it.

ps, I was looking at some info about the QBO and discovered that a feature that usually is present in an easterly phase is the Greenland high, combined witha very good SSTA signature bodes well for -ve NAO.

Edited June 8, 2007 by kold weather

[Mark Bayley]

Glad to here some good news at last. Apart from which i don't think we could have a repeat of last winter. Can we?

Edited June 8, 2007 by mark bayley

[Don]

The trouble with these promising signs is that we always see them every year and when it comes to the crunch Winter tends to end up being a damp squib. Always interesting to see though. Things will be far clearer come the end of September.

[noggin]

Things will be far clearer come the end of September.

Don't want to scare anyone, but that is only just over 3 months away!

It'll be upon us before we know it!

[kippure]

Don't want to scare anyone, but that is only just over 3 months away!

It'll be upon us before we know it!

The longest day of the year is under 2 weeks away. Wont be long till the nights will be drawing in EH! :blush:

[summer blizzard]

Yes, less than six months until winter begins.

[Don]

The Met Office Winter 2007/08 NAO forecast should be due out sometime in the next few weeks shouldn't it?

[Guest Viking141]

The Met Office Winter 2007/08 NAO forecast should be due out sometime in the next few weeks shouldn't it?

It was out on the 10th July last year. They use the figures from May to make this forecast so it takes them about a month to plough through the data.

[Lettucing Gutted]

The longest day of the year is under 2 weeks away. Wont be long till the nights will be drawing in EH! :blush:

The lengthening nights will still feel uncomfortably muggy like last year.

[Gavin P]

Remember the 2005 forecast (the -NAO one) wasn't released until September. I think they held it back until the saw what the dynamic model was predicting for winter. If this years SST's point towards a -NAO they may hold back longer than they did last year. Another advantage of waiting is to see what happens with La Nina.

[Stu_London]

Remember the 2005 forecast (the -NAO one) wasn't released until September. I think they held it back until the saw what the dynamic model was predicting for winter. If this years SST's point towards a -NAO they may hold back longer than they did last year. Another advantage of waiting is to see what happens with La Nina.

Whenever it comes out, I will be taking a great deal of notice - excellent forecast the last 2 years.

An regardless of GW or AGW, if the NAO and AO signals are correct, then the UK still has potential for severe weather.

[summer blizzard]

Remember the 2005 forecast (the -NAO one) wasn't released until September. I think they held it back until the saw what the dynamic model was predicting for winter. If this years SST's point towards a -NAO they may hold back longer than they did last year. Another advantage of waiting is to see what happens with La Nina.

Nope, NAO data was out in July, first forecast in August, an update calling for mild in Septemeber and then updates from thereon calling for cold.

[Gavin P]

A don't remember it being a complete disaster like that SB? From memory they was calling cold right from the very beginning? What made them go mild in September 2005?

Edited June 10, 2007 by Gavin P

[summer blizzard]

I am not sure, at the time we on here thought that they were reffering to a winter 1999 senario which was an above average winter with a negative NAO, though i think a lot of this was what there dynamical model was forecasting.

[BLAST FROM THE PAST]

Whenever it comes out, I will be taking a great deal of notice - excellent forecast the last 2 years.

Yes but remember the 66% success rate. They have had that so will this one go wrong?

BFTP

[Thundery wintry showers]

Yes, so far the Met Office have certainly done themselves proud in their seasonal forecasts. I heard from someone at UEA that the MetO's climate models had offered wildly differing scenarios for Winter 2006/07, one going for a cold winter and the other going for mild, and that was why the MetO were relatively vague that time (though correctly erring on the side of mild). Their 2005/06 forecast was especially successful.

[Gavin P]

Vorticity posted this anomaly chart in TWO forums earlier;

http://poet.jpl.nasa.gov/tmp/281511.gif

Which, does bear some similarity to the anomaly for May 1995;

http://poet.jpl.nasa.gov/tmp/281661.gif

Interesting.

Edited June 15, 2007 by Gavin P