Sea Surface Temperature And Sea Ice Trends(2)

[summer blizzard]

Indeed Fred, and those cold water anomalies extend to some depth in the central-eastern Pacific north of the equator. We should also remember how the last Nino event completely collapsed within this PDO regime, so neutral ENSO with a possible Nina by spring 09.

Glacier Point, i was just wondering whether you agree with my take on the current anomolies, or whether you see something different?

[summer blizzard]

Sea surface temperature anomolies have developed interestingly recently, with a slightly +PNA indicated, this is likely to mean a stronger Azores High, but west of its usual position, leading to low pressure quite close to the south west of the British Isles in around a months time.

I'd say my prediction was quite good, though perhaps less cyclonic than i expected.

Looking at the latest sea surface temperature anomolies, there are two main features that look to be driving the UK weather during the middle third of August, those are a mid-lattitude high in the eastern Pacific (active monsoonal trough - result or driver???), and a weak Bermuda high causing subsidence in the western Atlantic with low heights over Greenland (+AO, quiet monsoonal trough), with an amplified trough in the eastern Atlantic as a result of these synoptics leading to low pressure either over or just to the south of the UK with winds from an eastern quadrant a probable result.

[summer blizzard]

Looking at the latest sea surface temperature anomolies, in around a months time, there is a signal for high lattitude ridging in the western Pacific with a signal for low pressure at mid and low lattitudes, likely to result in high amounts of shear and a weak monsoonal trough. In the eastern Pacific, the downstream response to the affore mentioned troughing is for a mid and low lattitude ridge with the respnse to that being an increased Polar Vortex near Alaska/northwestern Canada. In the Atlantic, the signal is for blocking over western Greenland and a shallow Azores Low, prompting weak blocking over Europe however this in turn indicates troughing over northern Europe.

In summery, weak monsoonal trough (lack of tropical activity) and a signal for a cyclonic southwesterly/north westerly pattern over the UK.

[Gavin P]

SB, I think the SST's are developing in a way that indicates quite a wet and stomry early and mid Autumn period. So for September, I'd go for perhaps the wettest since 2000 and for October, potentially a very active month with fairly frequent gales and deep lows being spawned around NF as those warm waters there interact with ever cooling air in the polar regions. Would that be a fair assesment?

[mountain shadow]

SB, I think the SST's are developing in a way that indicates quite a wet and stomry early and mid Autumn period. So for September, I'd go for perhaps the wettest since 2000 and for October, potentially a very active month with fairly frequent gales and deep lows being spawned around NF as those warm waters there interact with ever cooling air in the polar regions. Would that be a fair assesment?

I think it would be fair to say that storms form near NF every autumn due to the interaction between cold polar air and a warmer ocean. Whether those storms run into the Uk is a different matter. With an earlier post alluding to a Polar Vortex towards Alaska and a Greenland High, this would indicate a southerly jet with the Uk and Ireland in the firing line for storms.

[James M]

One thing I've noticed is there always seems to be warmer waters around Southern Scandinavia as much as 4/5°C above average, is there any particular reason for this?

Edited August 6, 2008 by James M

[reef]

One thing I've noticed is there always seems to be warmer waters around Southern Scandinavia as much as 4/5°C above average, is there any particular reason for this?

Id say this is a result of the pattern of the last few summers. While we have been suffering from two mediocre summers, eastern Europe has baked quite nicely. As the Baltic and surrounding waters are rather shallow, they respond quickly with an increase in temperature. Similar used to happen in winter when an easterly flow caused rapid cooling and freezing of the same waters, but sadly this has become a rare event in the last 10-15 years.

A similar rapid heating occured in 2005 very early in the season, under high pressure and the 10C isotherm.

Temperatures close to average:

A week later after some warm days:

Edited August 6, 2008 by reef

[summer blizzard]

SB, I think the SST's are developing in a way that indicates quite a wet and stomry early and mid Autumn period. So for September, I'd go for perhaps the wettest since 2000 and for October, potentially a very active month with fairly frequent gales and deep lows being spawned around NF as those warm waters there interact with ever cooling air in the polar regions. Would that be a fair assesment?

Indeed, to me it looks like a classic zonal picture, cooler and wetter in the north and west.

[Gavin P]

Thanks man. I'm still learning this SST stuff and how it interacts with other teleconnections.

Edited August 6, 2008 by Gavin P

[Glacier Point]

One aspect of SSTA analysis to keep a keen eye on in the next few weeks.

A large body of cold water anomalies extending 50 - 100m below the surface in the Equatorial Atlantic with subsurface anomalies between -0.5 and -1.5.

http://www.ecmwf.int/products/forecasts/d/...al_time/xzmaps/

The easterly trades are continuing in the area and will intensify over the next few weeks due to seasonal changes. This wil continue to upwell colder water to the surface.

Current plots already show some colder anomalies:

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

I think it likely that we will see a mini-Nina in the Atlantic this winter. What impacts will this have ? Difficult to be point towards a specific overwhelming response because Pacific influences will be important. However, a logical response would be for a ridge in the Atlantic displaced northwards - possibly continuing the tilted NW-SE axis of the polar jetstream over Europe.

[BLAST FROM THE PAST]

One aspect of SSTA analysis to keep a keen eye on in the next few weeks.

I think it likely that we will see a mini-Nina in the Atlantic this winter. What impacts will this have ? Difficult to be point towards a specific overwhelming response because Pacific influences will be important. However, a logical response would be for a ridge in the Atlantic displaced northwards - possibly continuing the tilted NW-SE axis of the polar jetstream over Europe.

A good assessment there GP, I think that will support the 'early' winter for Europe as i expect a NW/SE assault which would produce an early snow season for the Alps [Nov particularly] and a decent autumn for the UK.

BFTP

[Glacier Point]

One aspect of SSTA analysis to keep a keen eye on in the next few weeks.

A large body of cold water anomalies extending 50 - 100m below the surface in the Equatorial Atlantic with subsurface anomalies between -0.5 and -1.5.

http://www.ecmwf.int/products/forecasts/d/...al_time/xzmaps/

The easterly trades are continuing in the area and will intensify over the next few weeks due to seasonal changes. This wil continue to upwell colder water to the surface.

Monthly change is showing a growing pool of subsurface cold water in the Atlantic and expansion of colder water in the Pacific with a second cold pool starting to evolve off the south American coast:

1 month ago:

http://www.ecmwf.int/products/forecasts/d/...mperature!/

Current:

http://www.ecmwf.int/products/forecasts/d/...al_time/xzmaps/

These Pacific anomalies seem to be tapping into the deep cold anomalies present just to the north at 140W.

http://www.ecmwf.int/products/forecasts/d/...al_time/yzmaps/

Current ENSO conditions show a recent drop in regions 3.4 and 4 in line with expanding cold surface anomalies:

http://www.bom.gov.au/climate/enso/indices.shtml

odds on a second Nina event in two years starting to shorten whilst the Atlantic picture is very interesting and far removed from what we have seen in the last 25 years.

Edited September 4, 2008 by Glacier Point

[TEITS]

whilst the Atlantic picture is very interesting and far removed from what we have seen in the last 25 years.

You've got me curious GP.

When you have time I would appreciate what you mean.

[Glacier Point]

last time that happend - 1976.

The theory would be that the cold anomalies force easterly trades to strengthen weakening the sub-tropical ridge and allowing northerly blocking as the energised jet takes a more southerly track. For all years in the sample where the DJF featured a cold equatorial Atlantic...this is the composite reanalysis....which validates the theory.

WOW, big -NAO

[SMU]

last time that happend - 1976.

The theory would be that the cold anomalies force easterly trades to strengthen weakening the sub-tropical ridge and allowing northerly blocking as the energised jet takes a more southerly track. For all years in the sample where the DJF featured a cold equatorial Atlantic...this is the composite reanalysis....which validates the theory.

WOW, big -NAO

Shouldnt your original post be for 32 years then....

Nice reanalysis chart- lets hope the 08/09 reanalysis looks something similar....

S

[beng]

Monthly change is showing a growing pool of subsurface cold water in the Atlantic and expansion of colder water in the Pacific with a second cold pool starting to evolve off the south American coast:

1 month ago:

http://www.ecmwf.int/products/forecasts/d/...mperature!/

Current:

http://www.ecmwf.int/products/forecasts/d/...al_time/xzmaps/

These Pacific anomalies seem to be tapping into the deep cold anomalies present just to the north at 140W.

http://www.ecmwf.int/products/forecasts/d/...al_time/yzmaps/

Current ENSO conditions show a recent drop in regions 3.4 and 4 in line with expanding cold surface anomalies:

http://www.bom.gov.au/climate/enso/indices.shtml

odds on a second Nina event in two years starting to shorten whilst the Atlantic picture is very interesting and far removed from what we have seen in the last 25 years.

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

If I'm reading those Euro graphics correctly, the subsurface cold anomaly in the atlantic maps to the surface cold anomaly to the SW of the UK which has been there for quite a while now. It's good though to see that this anomaly is supported at depth as it should mean it's got a good chance of persisting through the winter I would think. - EDIT - then again maybe not as I just noticed the subsurface anomaly chart is for the equator!

Have you seen the SOI in the last few weeks - the next la nina might be by this winter if it continues.

http://www.longpaddock.qld.gov.au/Seasonal...30DaySOIValues/

:lol:

Edited September 4, 2008 by beng

[david16]

You would think surely that the cold anomoly SST's SW of the UK if it persists would be a barrier to the usual seemingly never-ending conveyer belt of low presure systems sweeping across the UK during the winter months.

We live in hope based on that cold anomoly persisting that the yuck for once is not as long lasting or as intense as it has the last 2 dismal British winters.

Edited September 9, 2008 by david16

[summer blizzard]

Looking at the latest sea surface temperature anomolies, in around a months time, there is a signal for high lattitude ridging in the western Pacific with a signal for low pressure at mid and low lattitudes, likely to result in high amounts of shear and a weak monsoonal trough. In the eastern Pacific, the downstream response to the affore mentioned troughing is for a mid and low lattitude ridge with the respnse to that being an increased Polar Vortex near Alaska/northwestern Canada. In the Atlantic, the signal is for blocking over western Greenland and a shallow Azores Low, prompting weak blocking over Europe however this in turn indicates troughing over northern Europe.

In summery, weak monsoonal trough (lack of tropical activity) and a signal for a cyclonic southwesterly/north westerly pattern over the UK.

Well, i think that its fair to say that i got the zonal picture spot on.

[summer blizzard]

Well, we have a rather interesting hemispheric pattern which looks like it may occur in early to mid October after a reveiw of the sea surface temperature anomlies.

In short, the hemispheric pattern looks as though it will alost entirely be dictated by Pacific Tropical Convection which will help to establish a large mid to high lattitude ridge and subsequent heights over the Polar field, slowing down the Polar Jet and encouraging a negative NAO with bloking indicated to the north of the UK and troughing to the south west.

In summery, it looks like a more blocked pattern, but also a very easterly one which at this time of year means dull and dank.

[Anti-Mild]

last time that happend - 1976.

The theory would be that the cold anomalies force easterly trades to strengthen weakening the sub-tropical ridge and allowing northerly blocking as the energised jet takes a more southerly track. For all years in the sample where the DJF featured a cold equatorial Atlantic...this is the composite reanalysis....which validates the theory.

WOW, big -NAO

That's a brilliant reanalysis chart - cold flow across the UK coming straight from Svalbard, potential for lots of snow in the SE and E!

We live in hope!

[cheeky_monkey]

You would think surely that the cold anomoly SST's SW of the UK if it persists would be a barrier to the usual seemingly never-ending conveyer belt of low presure systems sweeping across the UK during the winter months.

We live in hope based on that cold anomoly persisting that the yuck for once is not as long lasting or as intense as it has the last 2 dismal British winters.

erm...why??...dont see that small area of minor marginally below sst will effect the jet stream

[summer blizzard]

Quick update: In the past week, there has been no real change in the pattern described above, so an easterly pattern looks to dominate the first half of October.

[Glacier Point]

Subsurface anomalies in the Pacific this time last year....

http://www.ecmwf.int/products/forecasts/d/...mperature!/

Now:

http://www.ecmwf.int/products/forecasts/d/...al_time/xzmaps/

The spatial arrangement is more or less the same although the strength of the anomaly is different this time round. Looking at the developments over the last month..

1 month ago:

http://www.ecmwf.int/products/forecasts/d/...mperature!/

shows how the warm anomalies off the South American coast have diminished and colder subsurface anomalies have expanded and worked upwards.

This increases the probability of a weak Nina developing into the winter and the development of other cold anomalies across the central Pacific (-PDO) will ensure that a low angular momentum base state prevails - just as last year. However, we have two important differences compared to last year in that the QBO and upper atmosphere is different whilst the centre for tropical convection in the Indian Ocean looks a little different.

[david16]

erm...why??...dont see that small area of minor marginally below sst will effect the jet stream

Mauybe it won't, but the Unisys chart looks a bit different to recent times at this time of year, and not just the (ever shringoing) small area SW of the British isles which is shrinking. but it must give cold lovers a lot more hope than in many many recent years.

Of course I'm not anticipating a 1963 or 1979 or whatever. I appreciate ther norm is a 2 or 3 month atlantic conveyer belt bar the odd brief northerly and the occasional high pressure over us giving us the only cold weather we are likely to have, and the SST anomllies could change to their norm December to February.

But if we get a week or 2 of cold snowy weather and then spells of 3 or 4 days here and there it would be a bonus and make a pleasant change from the norm. Of course not likely, but you never know if SST anomolies where they matter stay colder than normal during the winter months. Dark green/yellow on the SST anomoly chart around the icelandic coasts for 3 months December to February is not a pretty sight if you don't want to see non stop atlantic weather sweeping constantly across us for days and weeks on end.

It's just that I hate the SW stuff being our almost exclusive weather during the winter months as they have been most of the last 20 years. And just to keep the "It'll never snow again, global warming!" fraternity quiet if we do get a bit more prolonged widespread snow than we have had in recent time, more in hope than expectation of course.

Edited October 2, 2008 by david16

[summer blizzard]

Another quick update, there are two main factors which look as if they are going to control the weather around the first ten days of November...

1) Tropical Convection

2) As a result of this, a displaced northward Sub-Tropical High in the western Pacific which is going to lead to an amplified Pacific Jet Stream

3) As a result of warm air advection from the high pressure system, strong heights over the Pole

The knock on effect to the UK is that we will most likely see ridging over Greenland/Scandivia