Winter 2010/2011

[chionomaniac]

Some have just referred to the AO, NAO as a index of pressure in the Atlantic where as the

CPC have the NAO as one of 10 main teleconnections that can affect and control and change

the weather.

I personally think the AO has a bigger say than the NAO but that is just me.

Sometimes cc, I do wonder.

The AO, NAO pattern will teleconnect, for instance, to give the BI a certain type of weather depending on whether what phase it is in.

To add a link without explanation is totally unnecessary.

The AO, NAO are still indices of pressure differentials that are controlled by other, bigger drivers. To suggest that they have some kind of independence without other drivers is quite frankly ridiculous.

c

[cheeky_monkey]

To add a link without explanation is totally unnecessary.

The AO, NAO are still indices of pressure differentials that are controlled by other, bigger drivers. To suggest that they have some kind of independence without other drivers is quite frankly ridiculous.

c

yea..you go girlfriend

[johnholmes]

I would give up if I were you ch-you can lead a horse to water etc.

I'm happy with what you post.

Indeed your posts along with GP last winter were about the two most read items on lrf work in my view. And as I often say trying to isolate one meteorological factor from everything else, at whatever time scale is simply not possible.

Edited September 21, 2010 by johnholmes

[chionomaniac]

I would give up if I were you ch-you can lead a horse to water etc.

I'm happy with what you post.

Indeed your posts along with GP last winter were about the two most read items on lrf work in my view. And as I often say trying to isolate one meteorological factor from everything else, at whatever time scale is simply not possible.

Thanks, John.

[Thundery wintry showers]

The AO, NAO are still indices of pressure differentials that are controlled by other, bigger drivers. To suggest that they have some kind of independence without other drivers is quite frankly ridiculous.

I'm definitely among those who strongly support that assertion. Atmospheric circulation drives the weather, while indices reflect the relative prevalence of particular atmospheric patterns, e.g. a bias towards a strong Icelandic Low and strong Azores High is reflected by a strongly positive NAO, not the other way round. Similarly, last winter, it was exceptionally frequent high pressure near the North Pole that resulted in the exceptional negative AO, and not the other way round.

[Weather-history]

I don't get what this arguement over AO and NAO is all about?

To me, AO and NAO are just measurements of the strength of an effect. What causes this effect is a different thing but AO and NAO are not the cause, they are the result of the cause.

Its like voltage, current and resistance. Voltage is just a measurement of the difference in electrical potential energy between two points. Its a measurement of the effect, it is not the cause.

Thats how I see it as a layman.

[knocker]

Met. Office probability.

http://www.metoffice.gov.uk/science/specialist/seasonal/probability/glob_seas_prob.html

Edited September 22, 2010 by weather ship

[Don]

Met. Office probability.

http://www.metoffice.gov.uk/science/specialist/seasonal/probability/glob_seas_prob.html

Oh dear. Not a nice sight for the eyes of us cold weather lovers! Mind you, they were wrong last year, but that doesn't mean to say they will be this year of course. As ever, we wil see...

Edited September 22, 2010 by Don

[cooling climate]

Sometimes cc, I do wonder.

The AO, NAO pattern will teleconnect, for instance, to give the BI a certain type of weather depending on whether what phase it is in.

To add a link without explanation is totally unnecessary.

The AO, NAO are still indices of pressure differentials that are controlled by other, bigger drivers. To suggest that they have some kind of independence without other drivers is quite frankly ridiculous.

c

"Sometimes cc I do wonder". Rather pompous and arrogant don't you think.

I left a link without explanation so that other posters could read it and draw their own conclusions.

There are 10 teleconnections according to the CPC of which the AO/NAO are one.

May I suggest you go away and do some more reading or perhaps read my posts again and what I

have actually been saying then perhaps you will gain a better understanding of the climate and how

it all works.

This is my final word on the matter.

The end.

[cooling climate]

Oh dear. Not a nice sight for the eyes of us cold weather lovers! Mind you, they were wrong last year, but that doesn't mean to say they will be this year of course. As ever, we wil see...

If the Met office were forcasting a severe winter with buckets of snow I would

take no notice of it. There long range forcasts are no better than yours or mine hence

the reason why they have again stopped doing them, ie a complete waste of money.

[Methuselah]

Sometimes cc, I do wonder.

The AO, NAO pattern will teleconnect, for instance, to give the BI a certain type of weather depending on whether what phase it is in.

To add a link without explanation is totally unnecessary.

The AO, NAO are still indices of pressure differentials that are controlled by other, bigger drivers. To suggest that they have some kind of independence without other drivers is quite frankly ridiculous.

c

Thanks for that, CH...Indeces are indeed what they are...

[matt44myst]

"Sometimes cc I do wonder". Rather pompous and arrogant don't you think.

I left a link without explanation so that other posters could read it and draw their own conclusions.

There are 10 teleconnections according to the CPC of which the AO/NAO are one.

May I suggest you go away and do some more reading or perhaps read my posts again and what I

have actually been saying then perhaps you will gain a better understanding of the climate and how

it all works.

This is my final word on the matter.

The end.

come on, cc, even a rookie like me can understand the sense in what chiono, Mr Data, johnholmes and others are saying!

I followed your posts with such admiration last winter but right now you seem to be lashing out at anyone who disagrees with you....

I fully expect to be dealt with like Kentishkiwi was but even so the AO/NAO are indeces that correspond to pressure differentials between two places. They are a measurement of a synoptic situation that is already there. It is those synoptics which drive the weather and not the measurement index of them.

at least thats how i understand it...

[Cheshire Freeze]

Met. Office probability.

http://www.metoffice..._seas_prob.html

They could be right..... then again looking at the chart it suggests 90% of Europe more likely to have an above average winter and I bet if we could see the temperature forecast for the whole of the northern hemisphere it would probably show something similar. I'm not getting dragged into the whole METO warm bias debate but to me, having seen their forecasts for years prior to this one, it seems they seldom predict colder than the norm and if they can fail to spot such a winter as the one just gone I don't hold out much hope for any projected forecast.

Furthermore, last year the model didn't even just sit on the fence and produce no clear signal, it showed above average- the exact OPPOSITE of what materialised with Europe having one of its coldest winters in years. Then again, doesn't mean it won't be right this year

Edited September 22, 2010 by CreweCold

[cooling climate]

come on, cc, even a rookie like me can understand the sense in what chiono, Mr Data, johnholmes and others are saying!

I followed your posts with such admiration last winter but right now you seem to be lashing out at anyone who disagrees with you....

I fully expect to be dealt with like Kentishkiwi was but even so the AO/NAO are indeces that correspond to pressure differentials between two places. They are a measurement of a synoptic situation that is already there. It is those synoptics which drive the weather and not the measurement index of them.

at least thats how i understand it...

Yes you are right but I am intitled to my opinions without being ridiculed or talked down to

just because some posters have not clearly understood what I have written or meant,

although that of course could be down to me for not explaining myself in a way for others

to understand.

What you say above is quite correct by the way, but pressure differences over Iceland and

the Azores (the NAO as we choose to call it ) dominates our weather and in a very positive

or negative state can override the so called big drivers. This is why you can have Nino/Nina

winters that are not the same and +or - QBO winters that are not the same.

It is for this reason we such extremes in the weather such as summer of 76 and winters

of 47 and 63 etc.

[Osbourne One-Nil]

It's going to be a long winter I fear.

[Yorkshiresnows]

It's going to be a long winter I fear.

But we'll all enjoy it !!

I look forward to reading the posts of the vast majority on this tread and its good to see folks coming out of hibernation (if a little on the grumpy side).

This winter is still very much up in the air, as to what it delivers ...... which is what makes the leed in such fun.

Y.S

Edited September 22, 2010 by Yorkshiresnows

[Marcus_surfer]

Oh dear. Not a nice sight for the eyes of us cold weather lovers! Mind you, they were wrong last year, but that doesn't mean to say they will be this year of course. As ever, we wil see...

Metoffice have done terrible over the last few years with wrong forecasts and i'm glad they took down their winter/summer long range forecasts.

[BucksSnow]

yes poor forecasting......Lets all look foward to winter as in my eyes it starts once fridays over

[Methuselah]

I agree that the Meto hasn't done too well with their seasonal forecasts over the years. Funny thing is though that, barring the occasional 'hit', neither has anyone else??

Perhaps it says more about LRFs per se than it says about the Meto?

[Thundery wintry showers]

I remember that last winter, the MetO's probability maps had favoured a cold winter over eastern Europe and a mild one over western Europe, and that their official forecast was stripped to the absolute minimum level of detail, leaving out that detail, so they shot themselves in the foot. Otherwise they could have said "well, the colder weather extended further west than we thought, so we weren't completely wrong".

I note that on this occasion they expect the whole of Europe to be warm. Interestingly they particularly favour a warm Oct-Dec, while most of the teleconnections are favouring a warm start to 2011 following near average to cold weather in Oct-Dec 2010.

[Marcus_surfer]

For me, i personally don't think it will be as cold as last year. The temperatures last year were very cold and some very low temperatures were recorded over much of the UK. -22.3 °C in Scotland, -17.0 °C in the Midlands, and -16.0 °C in parts of Wales. Parts of Devon saw there coldest temperatures since 26th January 1945. This is just a feeling i have that we will not see these temperatures again this year.

I think we will get close to these temperatures, and we will see our fair amount of snow again across the whole of the UK. So all in all, a colder winter i would expect again, but maybe not as bone chilling as the previous winter but still with decent heavy snowfalls across much of the country. Just my opinion.

Edited September 22, 2010 by Marcus_surfer

[Methuselah]

I get the impression, Ian, that there's such a plethora of teleconnections, indeces, model runs, oscillations and so forth available for scrutiny, that compiling an accurate LRF (repeatedly and not just as a one-off!) is verging on the impossible??

In a way, I hope it is; I don't know what I'd talk about should all the day-to-day, week-to-week and month-to-month weather ever become as predictable as, say, gravity...

[jonboy]

I get the impression, Ian, that there's such a plethora of teleconnections, indeces, model runs, oscillations and so forth available for scrutiny, that compiling an accurate LRF (repeatedly and not just as a one-off!) is verging on the impossible??

In a way, I hope it is; I don't know what I'd talk about should all the day-to-day, week-to-week and month-to-month weather ever become as predictable as, say, gravity...

Couldn't agree more. If we don't fully understand how all the various teleconnections etc work (if we did longer term forcasts could be expected to be more accurate)then how can we be expected to understand what I believe to be the bigger drives of our climate the external planetary drivers which I believe to include such things orbit around the sun, solar wind intensity, gravitaional pull within the solar system, moon orbit, strength of helisphere, tilt of the earth etc. Each will impact on our atmosphere to some extent and must as a consequence affect our climate. These maybe small but generally our climate does operate within fairly small parameters.

My own gut feeling at present is that this winter is going to be colder than last and certainly a colder autumn. However I feel that we may have settled into a drier pattern and unless we see a more easterly pattern set up we may not see much snow

[Thundery wintry showers]

I get the impression, Ian, that there's such a plethora of teleconnections, indeces, model runs, oscillations and so forth available for scrutiny, that compiling an accurate LRF (repeatedly and not just as a one-off!) is verging on the impossible??

In a way, I hope it is; I don't know what I'd talk about should all the day-to-day, week-to-week and month-to-month weather ever become as predictable as, say, gravity...

I know from experience how difficult it is to predict more than a week ahead. My month-ahead forecasts involve a fair amount of detail for the first week, only moderate detail for the second week, and general pointers for weeks 3 and 4- simply because it becomes a nightmare to work out how the synoptics will "play out", even with bucketloads of GFS data in the N-W Datacentre (both free and in Extra), the newly-expanded UKMO/ECMWF data at Wetterzentrale, and the NOAA's teleconnections data. One irony that often arises is that the more data you have to go on, the more conflicting signals you get!

I think I have had some "hits" with my monthly forecasts over the years, but I also freely admit that there have been some that went wrong after a few days, or ended up partially right but for the wrong reasons- for example the December 2009 forecast didn't go very well. The Met Office's record has been similarly mixed, but unfortunately for the MetO most of its successes were clustered early on (the excellent forecast for Winter 2005/06 for instance) and most of the disasters clustered during 2008-10 and so the earlier successes have largely been forgotten by the public.

I doubt that we will ever be able to forecast accurately more than 2 weeks out, except maybe at a very generalised level- I get the impression that the amount of computing power needed to improve accuracy increases substantially as you get further and further ahead due to the "snowball effect" of minute differences in atmospheric variables throwing the weather patterns off-line.

[knocker]

I don't get what this arguement over AO and NAO is all about?

To me, AO and NAO are just measurements of the strength of an effect. What causes this effect is a different thing but AO and NAO are not the cause, they are the result of the cause.

Its like voltage, current and resistance. Voltage is just a measurement of the difference in electrical potential energy between two points. Its a measurement of the effect, it is not the cause.

Thats how I see it as a layman.

The most concise definition that I have come across for teleconnections is:

"Teleleconnections are defined as linkages over great distances of atmospheric and oceanic variables."

Of mild historical interest. The first use of the term was apparently used by A. Angstroem in an article, "Teleconnections of Climate Change in Present Time", in 1935.