Sea Surface Temperature And Sea Ice Trends(2)

[summer blizzard]

I agree, all we need is for a more negative NAO signiture to develop, which would require the mean ridge further north, also, it should be noted that warm sea surface temperature anomolies would favour higher pressure, so they are not nessaserily a bad thing.

Also, if anybody disagrees with my interpretation of the charts ever, please say so.

[The Enforcer]

Well what worries me is that it's now spring, the one time of year where in recent years the North Atlantic sea temperatures have got down to average values and yet this year we still seem to be under the influence of last year's warmth. There's bound to be some more warmth being added at some point this year, which I can only see equating to even more anomalously warm SSTs as winter 2007/2008 starts.

I don't buy this warm anomalies = high pressure = good sign for a cold winter theory, as the archive SST charts as far as they go back (2000 onwards) show the North Atlantic to have more positive temperature differences than negative differences for the late autumn/winter/early spring period. There hasn't been a cold/snowy period of long-term note this century, so obviously these warm anomalies are not helping. Their effect is two-fold:

1 - They encourage the wrong type of synoptics.

2 - When the right type of synoptics do pitch up (due to other overriding factors), they significantly modify the cold air.

A simplistic view can sometimes be best. In the autumn, I seem to remember taking a rather simplistic stance on the forthcoming winter based on what I thought the SSTs were saying - essentially autumn 2006 was showing negative anomalies in the North Pacific where autumn 2005 had shown positive anomalies. This to me indicated a different winter ahead and as 2005 had been blocked, I felt that this could only mean that it would be less blocked. Then the teleconnections boys pitched up saying it was more complex than that and that dipoles and tripoles and past patterns indicated a significant cold/snowy spell later in winter. Although I disputed 'snowy', the level of detail and consistency between views convinced me that they were onto something. I don't think anything significantly wintry is going to emerge in forthcoming winters, unless North Atlantic sea temperatures are significantly lowered and the signs for that occurring are not promising.

Edited March 20, 2007 by The Enforcer

[summer blizzard]

Enforcer, sea surface temperature anomolies are all about couplets, a warm anomoly in the north Atlantic combined with a cold anomoly and another warm anomoly in the Mediterranian will always favour a Bartlett which is the setup we have seen this winter, i never once said that sea surface temperatures currently indicated a colder winter.

[Glacier Point]

As our thoughts turn towards the Summer, we start to see some trends in N. Atlantic SSTA which, in isolation, suggest this year may be different to last year in terms of pressure anomaly pattern.

March - May SSTA 2006:

March so far 2007:

Differences observed to note:

1) There was a degree of weakness in +ve SSTA around the Azores during 2006 which, in my book, was a key factor in inducing that repeated high pressure pattern. This year, there as a trend at least towards a strong +ve anomaly between the Azores and Canaries - perhaps likely to support a high pressure cell ridgeing into Iberia.

2) The cold pooling off the eastern US was much further south last year. At this latitude this was ideal for positive height anomalies to develop and support ridgeing NE towards Europe. This year the pool is much further north which could underpin a stronger and flatter jet - especially with a greater snowfield over NE Canada.

Plenty of time for things to develop and I must stress that SSTAs are not the only game in town - we need only look at the impact of surface pressure over the Pole this winter - but I think the initial hints are for a moist, tropical maritime type pattern with numerous Spanish plumes.

GP

[The Enforcer]

Enforcer, sea surface temperature anomolies are all about couplets, a warm anomoly in the north Atlantic combined with a cold anomoly and another warm anomoly in the Mediterranian will always favour a Bartlett which is the setup we have seen this winter, i never once said that sea surface temperatures currently indicated a colder winter.

I'm not sure there's been much Bartlett-type warmth, just average mildness. The pattern has been a lack of anything remotely cold with the exception of the three brief cold spells, a month apart. But last autumn did you not forecast some very low CET values for the winter months, which meant you were not expecting the SST pattern at around that time to deliver a mild winter?

These couplets are important, but you can't get away from the fact that the warm seas locally are seriously undermining the potency of any cold spells that have arrived. In the last few years, for example, they have turned Reef's location from one of the best in a North-Easterly to one of the worst in terms of snowfall and leading me to record consecutive maximum temperatures of 9.2C and 8.2C in an inland location in what is supposed to be a 'bitterly cold airstream'.

Edited March 20, 2007 by The Enforcer

[Gavin P]

I really wouldn't worry about next winter at this point, guys.

And Thundery is right in any case. High SST's in the shallow waters around the UK are VERY prone to temperature changes and do not (IMO) stop a cold winter from developing. The warm anomolies in the Channel could be important in one aspect though, and that is they could help to increase very slightly, any heat we might pull in from off the Continent this summer (assuming we don't have a cool/wet spell at some point in the next 3 months, which would help bring the warm anomolies down)

Glacier Point, very interesting analysis. Generally your thinking it'll be another warm summer, but much wetter and high pressure generally weaker than in 2006? I wonder, if La Nina was to develop strongly (a big if) over the spring, what impact would that have on the summer, do you think?

Edited March 20, 2007 by Gavin P

[summer blizzard]

Plenty of time for things to develop and I must stress that SSTAs are not the only game in town - we need only look at the impact of surface pressure over the Pole this winter - but I think the initial hints are for a moist, tropical maritime type pattern with numerous Spanish plumes.

GP

I agree with your veiw , but on the other hand, the current anomolies spupport more high pressure closer to the British Isles, therefore i think that we could be looking at a summer similar to 2003, very hot, but with more support from the Azores High rather than a displaced high, but cloudier and wetter than last year.

I also think that this is already been shown in the setup indicated for early April.

Edited March 21, 2007 by summer blizzard

[summer blizzard]

As you can see, i still expect the main trough to be in the Gulf Of Alaska with the biggest thermal gradiant in the central Pacific, interestingly, the Pacific looks to be taking a more positive PDO look with a lowering of pressure in the western Pacific especially, however i do expect a ridge in the central Pacific in response to the stronger Jet Stream causing more warm air advection, because of the more positive PDO, i expect the PNA to be positive as a response, with the lowest pressure in the eastern USA however i expect the thermal gradiant to increase in the western Atlantic before the Jet Stream splits in the central Atlantic, supporting and Azores Low with a downstream high over the British Isles.

All in all, i expect the first half of April to be very warm, and thundery at times, but overall dry.

As you can see from the chart above, those are the major features i expect, however the main thing is the development of a mean area of high pressure in the central Pacific, which could indicate a potential pattern change in late April, though for the moment, it will be a shallow high.

[BLAST FROM THE PAST]

Nice La Nina developing there. Are we in for a Strong La Nina summer?

BFTP

[Gavin P]

Yes. If you believe this;

http://www.cpc.ncep.noaa.gov/products/peop...ino12SSTMon.gif

[reef]

Yes. If you believe this;

http://www.cpc.ncep.noaa.gov/products/peop...ino12SSTMon.gif

Thats a pretty amazing turnaround, I remember the forecast during January for a steady decline in the El Nino, reaching neutral by Autumn. It highlights the inaccuracies we still face in forecasting El Nino/La Nina conditions.

[summer blizzard]

It is more likely that we will see La Nina peak as moderate during the Autumn, meaning a weak to moderate La Nina summer.

[BLAST FROM THE PAST]

Thats a pretty amazing turnaround, I remember the forecast during January for a steady decline in the El Nino, reaching neutral by Autumn. It highlights the inaccuracies we still face in forecasting El Nino/La Nina conditions.

No Landscheidt predicted, using solar cycles the recent El Nino to a tee...he stated it would develop in July 06 and disappear during Feb 07...and he did this years ago. Thats what controls our climate

BFTP

[Glacier Point]

It is more likely that we will see La Nina peak as moderate during the Autumn, meaning a weak to moderate La Nina summer.

Not sure there SB, the models were playing catchup with the drop in the SSTAs during late Feb onwards and have still not fully registered the current situation. There is also some statistical basis for calling strong to moderate Nina when they form during the Spring.

This could well develop as the key factor this summer.

GP

[summer blizzard]

No Landscheidt predicted, using solar cycles the recent El Nino to a tee...he stated it would develop in July 06 and disappear during Feb 07...and he did this years ago. Thats what controls our climate

BFTP

Not true, in my opinion, the state of the PDO (Pacific Decadel Occilation) is equally as important as the ENSO, i believe the state of the Pacific Decadel Occilation was the only thing preventing a strong El Nino.

Not sure there SB, the models were playing catchup with the drop in the SSTAs during late Feb onwards and have still not fully registered the current situation. There is also some statistical basis for calling strong to moderate Nina when they form during the Spring.

This could well develop as the key factor this summer.

GP

At the moment, the PDO seems to be becoming more positive, as it has during the spring in recent years, i think that this will hold back the La Nina a little so that it peaks in the moderate range, as opposed to the strong range.

[Glacier Point]

Following on from the first assessment of Atlantic SSTAs, there have been some significant changes in the anomalies since the start of the month. This reanalysis illustrates the change in anomalies since March 1st:

Although the region around the Azores remains above average, there has been a significant cooling here with a general easing of the big +ve anomalies of the winter across the N. Atlantic, most probably related to the expansion of the polar cell in the last few weeks.

If this trend were to continue, we would start to replicate the conditions of last Summer with a potential displaced high pressure cell. However, we should also bear in mind that we may have a developing strong La Nina in place which argues for big troughing over western Europe and a stationary mid-Atlantic ridge which would tend to be cooler than recent Summers.

GP

[PersianPaladin]

I've noticed the easterly regime of late has helped to drag the 7C isotherm into the western north sea from Europe; which is good to see, although sadly rather belated.

[Stratos Ferric]

The current drop off in polar ice is marked: looking at the hemispheric anomaly we're now at, or below, the largest -ve anomaly on record!

[Bottesford]

Yes I see an earlier ice peak compared to last year:

http://arctic.atmos.uiuc.edu/cryosphere/IM...current.365.jpg

Fairly significant anonomly below average too.

[summer blizzard]

http://weather.unisys.com/surface/sst_anom.gif

Dont really have time to make a large update at the moment, but the pattern from the 25th to the 30th, should see a continuation of the status-quo, with low pressure attempting to undercut the European High and pumping up warm air, however with the main Polar Vortex to the east of Greenland, there are signs that retrogression could be on the cards.

[summer blizzard]

I hav'nt updated in a while, completely forgot lol...

I have annotated a chart, showing the main anomoly centres...

1) This feature is a weak surface high, with an upper level low to the west of it, causing amplification in the central Pacific...

2) This is a large high pressure area supporting a negative PNA in conjunction with a major trough to the west of the USA, this is causing large amplifiation in the eastern Atlantic and is primarily responsible for the continuation of a ridge over Europe.

3) This is a deep atmospheric trough driving a neagtive PNA pattern across the USA in 20 days time.

Firstly, i will say that i expect a continuation of the largely southerly/anticyclonic pattern though with low pressure making a little more progress west.

Secondly, i believe that we are seeing the emergance of a possible switch to a negative AO, the surface high in the Pacific will throw a secondary ridge into the Gulf Of Alaska and western Canada, if this splits, this will likely retrogress into the Arctic, if such a switch occured and there was still a negative PNA pattern, we could expect a northerly pattern to emergance with Greenland blocking and a Scandinavian Low.

[Gray-Wolf]

It is about time to start watching the summer melt up north and any SST anoms it may drive.

If we watch the West/SW of Greenland's coastal area we should start to see deep cold SST anoms as the SW tip of Greenland (facing the strongest of the sun) starts to pulse out into the Atlantic.

We should also look to see how quickly the shallow waters develop positive SST's this year as the north hots up (the Baltic got very warm last year and after the stunning start to spring I see no reason why we shouldn't see the same this year).

Finally, we should check to see how quickly the 'single season ice' ablates around the ice cap (and if any 'polynya's' open up facing the Bearing straights)

Edited April 22, 2007 by Gray-Wolf

[summer blizzard]

I hav'nt had much chance to update my forecast recently, but i have identified the key features which may affect out weather in around twenty days....

As you can see, the Pacific shows a highly amplified pattern with a mid Pacific ridge and Alutian Trough, while the Atlantic shows a mid-Atlantic ridge close to the British Isles suggesting dry but rather cool weather.

[summer blizzard]

I will have to update in detail later, but there are several key details which may affect our weather around the 10th June...

1) Quite a negative PDO signiture in the Pacific with a split Jet Stream and mean trough to the west of the USA with a highly amplified Jet Stream

2) Negative PNA signture with high pressure over western Atlantic aiding height rises over Greenland, and encouraging a negative AO

3) Shallow trough to south or south west of British Isles encouraging easterly type weather (high maxima, low mins)

4) I would summise that the trough to the west of the USA and mid-Atlantic ridge is La Nina showing its hand, which is being helped along by the developing negative PDO..

[beng]

http://weather.unisys.com/surface/sst_anom.html

Is it me, or is the North Atlantic cooling quite rapidly (relative to the average) at the moment? Still looks reasonable for a negative NAO forecast from the MO based on the surface temps anyway.

Edited May 23, 2007 by beng