Autumn And Winter

[memories of 63]

Morning all,

Haven't posted since last winter. I don't know if this is the correct thread but I've just read an article about a strong Il Nino event occuring this year. Any thoughts on what impact that will have on our weather systems in the next few months.

[BrickFielder]

Morning all,

Haven't posted since last winter. I don't know if this is the correct thread but I've just read an article about a strong Il Nino event occuring this year. Any thoughts on what impact that will have on our weather systems in the next few months.

The frequency of persistent high-latitude ridging events (commonly referred to as blocking) over the North Pacific–Alaskan region is investigated using a 44-winter record of daily 500-mb height fields. The winters are stratified in accordance with the phase of the El Niño–Southern Oscillation (ENSO) cycle and according to the sign of the seasonally averaged PNA index. It is found that the occurrence of blocking in the Bering Strait region is sensitive to the averaged polarity of the PNA pattern but is even more sensitive to the phase of the ENSO cycle. Sixty-nine percent more days of blocking are observed during winters occurring during the cool phase of ENSO, compared to those occurring during the warm phase. ENSO-related differences in blocking frequency are found to be associated with changes to both the mean and variance of the circulation over the North Pacific. The variance of geopotential heights on timescales corresponding to the lifetime of blocking events is found to be higher over the Bering Strait region in the cool phase of the ENSO cycle.

James A. Renwick and John M. Wallace

This means that we are less likely to have a blocked pattern over the north pacific which generally means less high pressure in the Bering Strait. This being half of the AO index suggests that Pacific conditions are likely to try to change the north atlantic to the same conditions. This would perhaps indicate a bias towards low pressure towards greenland and iceland. Where last winter there was a fair amount of blocking and easterly conditions there will be a bias towards less of that this winter. This does not necessarily mean less snow but could indicate that it is likely to come from the north rather than the east. The northern hemisphere is actually quite cloudy for this time of year and according to planetary albedo rules( lots of low cloud cools the planet) this could indicate a rapid cool down this autumn and a more southerly jet during the winter (placing us on the cold snowy side more often).

Repeated signals keep appearing in GFS for some quite stormy weather up ahead and it is starting to come into a reliable time frame.

Very windy and Wet.

[memories of 63]

Thanks very much for the comprehensive reply. I'll be watching for any devlopments along the llines you mentioned, it could be interesting.

[Glacier Point]

In answer to this:

http://www.netweather.tv/forum/index.php?s...st&p=781636

What does El Nino mean for the winter ? - I'm working on some reanalysis right now and it certainly makes for some provoking possibilities. I'll post a separate thread if no one has done so by that time.

In the interim, I think we need to work on the assumption of a weak becoming moderate El Nino event this winter with a Multivariant El Nino Southern Oscillation Index (MEI) in the range 1 to 1.5. The reanalysis is suggesting:

1) A certainty (and I mean that) for the sub-tropical Pacific and Atlantic jets to be very strong, especially given the SSTA couplets within these regions:

2) Significant inter-month variability in the Arctic Oscillation (AO) and Pacific North America Pattern (PNA) with December panning out as average and quiet, big -ve AO and North Atlantic Oscillation (NAO) January continuing into February but with increasing trends to mild.

These are of course are not insulated from other impacts, not least the possibility of a -ve Pacific Decadal Oscillation and warm sea surfaces across the north Atlantic sector currently signalling a -ve NAO. I'm also looking at the potential for quite an amplfied flow pattern care of those cold anomalies in the eastern Pacific which are showing up nicely in current seasonal SSTA maps:

http://www.cdc.noaa.gov/map/images/sst/sst.anom.seasonal.gif

Much however could change over the next few months, particularly within the Northern Atlantic.

GP

[Dawlish]

Morning all,

Haven't posted since last winter. I don't know if this is the correct thread but I've just read an article about a strong Il Nino event occuring this year. Any thoughts on what impact that will have on our weather systems in the next few months.

It's a good question, 63, wherever you post it!

Firstly, you are right about the El Nino. This is confimed by NOAA. This was put out by them only yesterday.

http://www.cpc.noaa.gov/products/analysis_.../enso_advisory/

BrickFielder's analysis is well worthwhile and possible. I'd approach it from another angle, though.

The last year of a full-blown El Nino was 1998 and we are overdue. Globally, an El Nino has a marked warming effect and 1998 still remains the warmest year (joint with 2005) on record. Since 1998, the world has continued to warm and last year, tying with 1998 (2005 was actually marginally warmer, though it wasn't significant enough for NOAA to call) in a non-El Nino year, was extra confirmation of the continuation of this warming trend (if any is still needed).

It's possible, maybe probable, that with an El Nino, 2007 will be the warmest global year since records began.

NW Europe can't be completely immune to that. This winter may not see effects, though effects are already being experienced in the tropics and Equatorial oceans and synoptics may throw a spanner in the warming works, but if there is no spanner and synoptics which favour warmth, both this winter and next year could be exceptionally warm.

It depends on the strength of the developing El Nino, but it could have massive effects, not only on the Pacific rim, but also much further afield. If GW continues, as all the evidence shows it will do, some years, seasons and months, won't just be warmer, they'll be unbelievably, never been experienced before warmer, in an upward spike, in a warming trend. People will starve, in some drought-vulnerable parts of the tropics and desert fringes as a result, and we're likely to experience our hottest months ever. That really isn't scaremongering - that's going to happen if the warming trend continues and this El Nino amplifies it.

Paul

Edited September 14, 2006 by Dawlish

[memories of 63]

Gosh Dawlish, I didn't realise I'd stimulate such a detailed discussion from such a 'simple' question. Don't know if I like your armageddon scenario though!!! If I could I'd join SACRA so you know where I'm coming from.

If more rapid warming does occur, could this also increase the rate of melting of the Greenland icesheet, decrease salinity of the NA and reduce/stop the THC - bringing about cooler conditions to the British Isles.

[Bottesford]

Gosh Dawlish, I didn't realise I'd stimulate such a detailed discussion from such a 'simple' question. Don't know if I like your armageddon scenario though!!! If I could I'd join SACRA so you know where I'm coming from.

If more rapid warming does occur, could this also increase the rate of melting of the Greenland icesheet, decrease salinity of the NA and reduce/stop the THC - bringing about cooler conditions to the British Isles.

We REALLY don't want that to happen! It'd be disaster for the whole of western Europe & probably the whole world...

[Dawlish]

Gosh Dawlish, I didn't realise I'd stimulate such a detailed discussion from such a 'simple' question. Don't know if I like your armageddon scenario though!!! If I could I'd join SACRA so you know where I'm coming from.

If more rapid warming does occur, could this also increase the rate of melting of the Greenland icesheet, decrease salinity of the NA and reduce/stop the THC - bringing about cooler conditions to the British Isles.

I'm a lot more sceptical on that one, 63. That really is scarmongering! My discussions with Petr Chlek, a Greenland climate researcher, who is in the vanguard of recent work and whose 2006 paper and its conclusions show clearly that Greenland temperatures are not being forced by CO2, only add to my scepticism.

Personally, I think we may be looking at hundreds, probably thousands of years, before the Greenland ice reacts in that kind of way, but that's only a personal opinion. I know of the research that may point to climate change possibly having occurred in the past over decades, rather than millennia, but we are all speculating under current GW conditions on that one.

GP's given another analysis of the possible effects of an El Nino on another thread. I'm sure you've found it and it is worth a read!

My scenario really isn't armaggedon stuff and I am not into scaremongering! i must be one of the harshest realists on netweather! It is completely mainstream science and is the forecasts from most GW researchers and modellers. Semi-arid regions, like the Sahel are extremely likely to become drier and that will lead to drought and starvation. It has been going on, as the global climate has been changing, since at least the Biafra drought in the late 60s and it continues today in Sudan. Too many people; not enough rainfall. An El nino will only make it worse.

Paul

Edited September 14, 2006 by Dawlish

[memories of 63]

I'm a lot more sceptical on that one, 63. That really is scarmongering! My discussions with Petr Chlek, a Greenland climate researcher, who is in the vanguard of recent work and whose 2006 paper and its conclusions show clearly that Greenland temperatures are not being forced by CO2, only add to my scepticism.

Personally, I think we may be looking at hundreds, probably thousands of years, before the Greenland ice reacts in that kind of way, but that's only a personal opinion. I know of the research that may point to climate change possibly having occurred in the past over decades, rather than millennia, but we are all speculating under current GW conditions on that one.

Paul

Yes, I think I know what you mean. I was a VERY firm believer in GW up until about 18 months ago. I'm now edging towards the 'normal' oscillation in global climate. I think the planet's ability to absorb short term effects is underrated, although it's always a good idea to use any sort of energy in the most efficient manner possible.

I'm not sure about the thousands of years for a change to occur. There was some interesting biological evidence published that indicated a rapid change in some species of beetle, linked to changes in climate.

BTW, grapes were succesfully grown by the Romans in Britain only a couple of thousand years ago, before anyone thought of GW!

[Dawlish]

Yes, I think I know what you mean. I was a VERY firm believer in GW up until about 18 months ago. I'm now edging towards the 'normal' oscillation in global climate. I think the planet's ability to absorb short term effects is underrated, although it's always a good idea to use any sort of energy in the most efficient manner possible.

I'm not sure about the thousands of years for a change to occur. There was some interesting biological evidence published that indicated a rapid change in some species of beetle, linked to changes in climate.

BTW, grapes were succesfully grown by the Romans in Britain only a couple of thousand years ago, before anyone thought of GW!

I don't think there is any doubt about GW ie we are in a warming phase, but I'm not completely convinced and I understand yours and other people's reservations about Anthropomorphic GW. The two have to be kept very separate!

Paul

[summer blizzard]

In response to Brickfielders post first, this fits in well with my thoughts on the QBO and El Nino, in that i expect a more or less neutral AO over the winter period with December the most likely month for a positive AO and February the most likely month for a negative AO. There has been reasearch on another forum which suggests that a westerly QBO encourages El Nino and that a westerly QBO is also linked to a positive AO in the same way that a easterly QBO encourages a negative AO.

The fact that the northern hemisphere is cloudyer than normal in a solar minima exites me greatly, not just for the reasons you have stated but because it raises the possibility of a 1947 type senario.

In answer to this:

http://www.netweather.tv/forum/index.php?s...st&p=781636

What does El Nino mean for the winter ? - I'm working on some reanalysis right now and it certainly makes for some provoking possibilities. I'll post a separate thread if no one has done so by that time.

In the interim, I think we need to work on the assumption of a weak becoming moderate El Nino event this winter with a Multivariant El Nino Southern Oscillation Index (MEI) in the range 1 to 1.5. The reanalysis is suggesting:

1) A certainty (and I mean that) for the sub-tropical Pacific and Atlantic jets to be very strong, especially given the SSTA couplets within these regions:

2) Significant inter-month variability in the Arctic Oscillation (AO) and Pacific North America Pattern (PNA) with December panning out as average and quiet, big -ve AO and North Atlantic Oscillation (NAO) January continuing into February but with increasing trends to mild.

These are of course are not insulated from other impacts, not least the possibility of a -ve Pacific Decadal Oscillation and warm sea surfaces across the north Atlantic sector currently signalling a -ve NAO. I'm also looking at the potential for quite an amplfied flow pattern care of those cold anomalies in the eastern Pacific which are showing up nicely in current seasonal SSTA maps:

http://www.cdc.noaa.gov/map/images/sst/sst.anom.seasonal.gif

Much however could change over the next few months, particularly within the Northern Atlantic.

GP

In regards to a moderate EL Nio during winter going by the MEI, the seasonal anologues at the moment are:

1951

1976

1977

All three anoologues observed a weak El Nino Autumn followed by a neutral Nino winter, except for 1977 which observed a weak El Nino during winter.

In regards to point one, i agree, this should also set us up for a fairly stormy Autumn as the Jet Stream progresses southward.

In reagrds to pint two, i also agree however this will depend on the EPO, at the moment, this is showing a trend to negative however this goes against the El Nino which suggests a positive EPO, the likelyhood for me is that the warm sea surface temperature anomoly in the central Pacific will move eastward, encourgaing a more positive PNA, this will also encourage a high lattitude ridge in the Pacific, indicative of a negative AO.

[memories of 63]

1947 being mentioned in September!!!! Is this a record

[Big Bear]

Not only is the northern hemisphere much cloudyer than normal, we peak at a solar minimum now AND there is brand new evidence that the global ocean mean temperature dropped suddenly by 20% between 2003 & 2005.

This may not have had enough time to affect last winter but could it perhaps knocking on our doors come December?

Details here: http://www.ocregister.com/ocregister/opini...cle_1245606.php

[Shiny_Bottom_1]

Not only is the northern hemisphere much cloudyer than normal, we peak at a solar minimum now AND there is brand new evidence that the global ocean mean temperature dropped suddenly by 20% between 2003 & 2005.

This may not have had enough time to affect last winter but could it perhaps knocking on our doors come December?

Details here: http://www.ocregister.com/ocregister/opini...cle_1245606.php

Thats one hell of a drop, although i'm not sure if this is something that has occured before (or at least within that time frame).

Still, we still have 80% of the heat from the last 50 years, but saying that, a very interesting article.

[Dawlish]

Not only is the northern hemisphere much cloudyer than normal, we peak at a solar minimum now AND there is brand new evidence that the global ocean mean temperature dropped suddenly by 20% between 2003 & 2005.

This may not have had enough time to affect last winter but could it perhaps knocking on our doors come December?

Details here: http://www.ocregister.com/ocregister/opini...cle_1245606.php

All possible Big Bear. Thanks for the link. It's very interesting. It should also add confidence to the one's who have bet on a colder winter! The odds still stand. Despite the possible cooling, 2005 still ended up the warmest year ever and this summer, globally, will be close to the warmest ever; certainly in the top 10. There'd have to be one hell of a time-lag involved for 2003-5 pacific ocean cooling not affected the world's climate up until now, but will affect the world's climate this winter. It doesn't seem to have had an effect on atmospheric temperatures at all, which continue to rise.

Paul

[Glacier Point]

SB,

not sure at all about those anologs based on a receeding MEI into winter. Even if this happens, the next few months look to be for increasing strength El Nino given the warm sub-surface anomalies which have ballooned up in the last few weeks

http://img444.imageshack.us/img444/4973/wkxzteqanmvb7.gif

This will ensure at least the core of the winter being influenced by a weak to moderate El Nino if it continues into November.

In so far as the EPO, this is really being driven by a continuation of cold anomalies down the eastern Pacific allied to strong positive anomalies to the west very much akin to a -ve phase PDO. The -ve PDO / +ve MEI is an unusual teleconnector - I can find only 3/4 good matches for this during the winter time - although the net effect will I think be increased probability of +ve phase PNA and troughing out east.

Could it be the last year that the decreasing solar flux was masked somewhat by the combination of -ve PDO / -ve MEI during the late Autumn and Winter ? This year looks very different in terms of the SSTA:

2005 July - November

2006 July to date

http://www.cdc.noaa.gov/map/images/sst/sst.anom.seasonal.gif

just look at the differences in the polar anomalies, the eastern Pacific, central Atlantic and Pacific equitorial waters - could not be much more different.

GP

[Big Bear]

All possible Big Bear. Thanks for the link. It's very interesting. It should also add confidence to the one's who have bet on a colder winter! The odds still stand. Despite the possible cooling, 2005 still ended up the warmest year ever and this summer, globally, will be close to the warmest ever; certainly in the top 10. There'd have to be one hell of a time-lag involved for 2003-5 pacific ocean cooling not affected the world's climate up until now, but will affect the world's climate this winter. It doesn't seem to have had an effect on atmospheric temperatures at all, which continue to rise.

Paul

Cheers paul

maybe there will be some kind of time lag though? Last winter was the coldest in years wasn't it? perhaps it signals the start of a downward trend. Maybe these things are more complex & take more understanding than meets the eye.

Talking of 1947, heres my one of my favourite charts of all time: http://www.weathercharts.org/synoptic_chart_31Jan1947.jpg

And just to wet the taste buds, some juicy archive info from the met office: http://www.met-office.gov.uk/education/sec...nts/winter.html

All possible Big Bear. Thanks for the link. It's very interesting. It should also add confidence to the one's who have bet on a colder winter! The odds still stand. Despite the possible cooling, 2005 still ended up the warmest year ever and this summer, globally, will be close to the warmest ever; certainly in the top 10. There'd have to be one hell of a time-lag involved for 2003-5 pacific ocean cooling not affected the world's climate up until now, but will affect the world's climate this winter. It doesn't seem to have had an effect on atmospheric temperatures at all, which continue to rise.

Paul

Cheers paul

maybe there will be some kind of time lag though? Last winter was the coldest in years wasn't it? perhaps it signals the start of a downward trend. Maybe these things are more complex & take more understanding than meets the eye.

Talking of 1947, heres my one of my favourite charts of all time: http://www.weathercharts.org/synoptic_chart_31Jan1947.jpg

And just to wet the taste buds, some juicy archive info from the met office: http://www.met-office.gov.uk/education/sec...nts/winter.html

[summer blizzard]

1947 being mentioned in September!!!! Is this a record

Nope..

Last summer, i was voted the third most likely person to cold ramp, this was mainly because i issued a detailed weakly forecast stating that the coming winter would be on the scale of 1947, i became more of a realist during Autumn and changed my forecast accordingly.

Big Bear, thanks for the article, it is quite interesting, although it could be a normal thing to happen during a solar minima, i do not believe that we have records from the solar minima of 1996.

If i remeber correctly, the NAD has slowed by over 30% since 1950, with around 15% of that talking place since the year 2000, perhaps that is the reason for the loss of heat??

[summer blizzard]

SB,

not sure at all about those anologs based on a receeding MEI into winter. Even if this happens, the next few months look to be for increasing strength El Nino given the warm sub-surface anomalies which have ballooned up in the last few weeks

http://img444.imageshack.us/img444/4973/wkxzteqanmvb7.gif

This will ensure at least the core of the winter being influenced by a weak to moderate El Nino if it continues into November.

In so far as the EPO, this is really being driven by a continuation of cold anomalies down the eastern Pacific allied to strong positive anomalies to the west very much akin to a -ve phase PDO. The -ve PDO / +ve MEI is an unusual teleconnector - I can find only 3/4 good matches for this during the winter time - although the net effect will I think be increased probability of +ve phase PNA and troughing out east.

Could it be the last year that the decreasing solar flux was masked somewhat by the combination of -ve PDO / -ve MEI during the late Autumn and Winter ? This year looks very different in terms of the SSTA:

2005 July - November

2006 July to date

http://www.cdc.noaa.gov/map/images/sst/sst.anom.seasonal.gif

just look at the differences in the polar anomalies, the eastern Pacific, central Atlantic and Pacific equitorial waters - could not be much more different.

GP

I agree that the warming of the El Nino regions looks to continue, and as a result, i suspect that the 1977 anologue is more relevant, which peaked in November although i do not see a moderate El Nino.

Personally, i do not think that the negative PDO/El Nino combination will continueinto winter, for the reason i have already stated (warm anomoly moving east) however if it did, i think that it would favour a mean trough over almost all of the USA and a mean ridge over almost all of Canada.

Glacier Point, that comparison is somewhat invalid as it is not of the same time period although it does illustrate the prospect of a more southerly tracking Jet Stream and a greater cold pool.

Edited September 14, 2006 by summer blizzard

[Dawlish]

If i remeber correctly, the NAD has slowed by over 30% since 1950, with around 15% of that talking place since the year 2000, perhaps that is the reason for the loss of heat??

Sorry Summer; I have to pick you up on that one.

I know of no evidence that any current in the NAD, moving towards our shores, has reduced at all. Not a single one. The 2005 Southampton Uni study, oft misquoted across the Internet and always by hacks, found that one, seldom measured, North to South current had decreased by 30% since the last measurement 5 years ago. Prof Wadham's study of 2004/5 found less sinking cold water columns in the Greenland Sea, but not a single study has ever found that the NAD has reduced in intensity. Both, excellent, studies fuelled enormous speculation about the state of the thermohaline circulation, some of it scientifically very valid, but both studies cautioned extrapolation towards any slowing of the NAD - of course the studies were not fully read and the caution expressed by the researchers was completely ignored in favour of good press.

So many people picked up on these untruths and now half (OK guys and gals - a guess ) the people on weather discussion boards still believe this untruth that the NAD has slowed by 30%.

It hasn't.

If anything, SST's would indicate a strengthening of the current over the timescales you indicate.

If anyone knows of any studies which have proved the slowing of the NAD/Gulf stream, please tell us about them. I for one am dying to see the results of a lot of current research.

Paul

PS Current research......geddit, geddit?

Edited September 14, 2006 by Dawlish

[shuggee]

If you want to discuss the 'bigger picture' around climate change, NAD shutdown, Ice Age Now etc. do so in the Environment Change Forum here:

http://www.netweather.tv/forum/index.php?showforum=8

Meanwhile, for the upcoming months I've opened a lovely new, fresh thread here:

http://www.netweather.tv/forum/index.php?showtopic=32724