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Posted
  • Location: Horsham, West sussex, 52m asl
  • Location: Horsham, West sussex, 52m asl

    after fading at the beginning of the month,

    anomnight.9.1.2016.gif

    the 'blob' is getting bigger again...

    anomnight.9.15.2016.gif

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    So, have you ever wondered how exactly would N Atlantic look like if you would pump out all the water? Well, its one big mountain range (MAR - Mid Atlantic Ridge). It gives you a feeling and a differe

    Yeah, I think that's quite a disingenuous chart (no reflection on yourself , of course!).   If we look at the months used in that chart, and the 9 months leading up to them, we get the following:  

    The 13 hours later this arrived..   Many thanks for your enquiry regarding North Atlantic sea surface temperatures. I have spoken to the relevant scientists within the Met Office Hadley Centre who h

    Posted Images

    Posted
  • Location: Surrey and SW France.
  • Location: Surrey and SW France.

    The 'blob' that is really impressive currently is the hot spot in the NE Pacific. It faded a bit last year but is back with a vengence now. Was this not linked with the extremely positive PNA pattern over north America two winters ago?

    In between the Nina signature in the tropical Pacific and the big Kara/Barents positive anomaly, it is all looking very similar to 2014 at our latitudes.

    2014  2014091700_054_G6_global_I_SEASON_tm@lg@    2016  2016091700_054_G6_global_I_SEASON_tm@lg@

    Atlantic sub-surface will still be cold so I expect the cold blob to extend if the autumn sees big depressions in the central north Atlantic.

    http://weather.gc.ca/saisons/sea-snow_e.html

     

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    Posted
  • Location: Leeds/Bradford border, 185 metres above sea level, around 600 feet
  • Location: Leeds/Bradford border, 185 metres above sea level, around 600 feet

    Indeed Nouska, such a pronounced atmospheric anomoly in the Pacific should support some wave breaking and also force a more active southern stream in the US (with a +PNA).

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    • 3 weeks later...
    Posted
  • Location: Surrey and SW France.
  • Location: Surrey and SW France.

    A southern hemisphere connection has been a theory mooted previously in scientific studies - some new research to add to the idea.

    Gulf Stream slowdown tied to changes in Southern Hemisphere

    http://onlinelibrary.wiley.com/doi/10.1002/2016GL069789/abstract;jsessionid=A3BC7DD017659FBCA9FBF7A3015D3590.f02t04

    Abstract.

    Recent measurements of the strength of the Atlantic overturning circulation at 26°N show a 1 year drop and partial recovery amid a gradual weakening. To examine the extent and impact of the slowdown on basin wide heat and freshwater transports for 2004–2012, a box model that assimilates hydrographic and satellite observations is used to estimate heat transport and freshwater convergence as residuals of the heat and freshwater budgets. Using an independent transport estimate, convergences are converted to transports, which show a high level of spatial coherence. The similarity between Atlantic heat transport and the Agulhas Leakage suggests that it is the source of the surface heat transport anomalies. The freshwater budget in the North Atlantic is dominated by a decrease in freshwater flux. The increasing salinity during the slowdown supports modeling studies that show that heat, not freshwater, drives trends in the overturning circulation in a warming climate.

    Paper paywalled but a bit more info here.

    https://www.sciencedaily.com/releases/2016/10/161005084916.htm

    Looking at other observations to determine the cause, the researchers ruled out what had been the prime suspect until now: that massive melting and freshening in the North Atlantic could stop water from sinking and put the brakes on the overturning circulation, which moves warmer water north along the ocean's surface and sends cold water southward at depths.

    "It appears that this 10-year slowdown is not related to salinity," Kelly said. In fact, despite more ice melt, surface water in the Arctic is getting saltier and therefore denser, she said, because of less precipitation. "That means the slowdown could not possibly be due to salinity -- it's just backwards. The North Atlantic has actually been getting saltier."

    Instead, the authors saw a surprising connection with a current around the southern tip of South Africa. In what's known as the Agulhas Current, warm Indian Ocean water flows south along the African coast and around the continent's tip toward the Atlantic, but then makes a sharp turn back to join the stormy southern circumpolar current. Warm water that escapes into the Atlantic around the cape of South Africa is known as the Agulhas Leakage. The new research shows the amount of leakage changes with the quantity of heat transported northward by the overturning circulation.

    "We've found that the two are connected, but I don't think we've found that one causes the other," Kelly said. "It's more likely that whatever changed the Agulhas changed the whole system."

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    Posted
  • Location: New Forest (Western)
  • Weather Preferences: Fascinated by extreme weather. Despise drizzle.
  • Location: New Forest (Western)

    Just watched this presentation on the possible changes to the mean track of the ocean currents in in conjunction with continued weakening.

    Could the Labrador current be replaced by the Gulf Stream waters along the Eastern Seaboard?

    Als an interesting final slide showing increased storminess across the U.K. and N Europe.

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    Posted
  • Location: Springfield, Chelmsford, Essex 30Mtr ASL
  • Weather Preferences: snowy or sunny but not too hot!
  • Location: Springfield, Chelmsford, Essex 30Mtr ASL

    Good morning everyone,

    As a weather novice still learning by reading the excellent Netweather Forum I wish to ask what a lot of you more knowledgeable folk might seem to be a stupid question. What does cold water encourage? Is it the development of low or high pressure. The reason I ask is that with for example the recent Hurricane Matthew  as soon as it arrived over cooler waters it began to lose intensity. On the other hand if warm air travels over cold water does this not increase the likelihood of depressions forming. To me that seems to be contradictory to the Hurricane  situation.

    Clarification would be appreciated.

    Kind Regards

    Dave

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    Posted
  • Location: Marton
  • Location: Marton
    1 hour ago, claret047 said:

    Good morning everyone,

    As a weather novice still learning by reading the excellent Netweather Forum I wish to ask what a lot of you more knowledgeable folk might seem to be a stupid question. What does cold water encourage? Is it the development of low or high pressure. The reason I ask is that with for example the recent Hurricane Matthew  as soon as it arrived over cooler waters it began to lose intensity. On the other hand if warm air travels over cold water does this not increase the likelihood of depressions forming. To me that seems to be contradictory to the Hurricane  situation.

    Clarification would be appreciated.

    Kind Regards

    Dave

    By no means an expert. Remember though the waters are much warmer in the Hurricane zone, up to 30c i think, so when it enters the temperate North Atlantic it will lose intensity because of the relative cooler waters. So we in the  Uk may recieve the left over depressions of these storms if the path of the Jet Stream is at the Uk. The development of HP and LP over temp gradients of water is another subject in itself.

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    Posted
  • Location: Surrey and SW France.
  • Location: Surrey and SW France.
    1 hour ago, claret047 said:

    Good morning everyone,

    As a weather novice still learning by reading the excellent Netweather Forum I wish to ask what a lot of you more knowledgeable folk might seem to be a stupid question. What does cold water encourage? Is it the development of low or high pressure. The reason I ask is that with for example the recent Hurricane Matthew  as soon as it arrived over cooler waters it began to lose intensity. On the other hand if warm air travels over cold water does this not increase the likelihood of depressions forming. To me that seems to be contradictory to the Hurricane  situation.

    Clarification would be appreciated.

    Kind Regards

    Dave

    A tropical cyclone is a warm core storm - relying on ocean heat content to maintain convective activity. As soon as it travels over cooler waters, that convection dies and the storm/hurricane weakens. Mid latitude storms are cold core, relying on air/sea temperature contrasts for baroclinicity.

    http://www.met.rdg.ac.uk/~storms/concep/baro_inst/

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    Posted
  • Location: Springfield, Chelmsford, Essex 30Mtr ASL
  • Weather Preferences: snowy or sunny but not too hot!
  • Location: Springfield, Chelmsford, Essex 30Mtr ASL

    Thank you Matthew Wilson and Nouska for your very informative replies. I now understand why.

    Kind Regards

    Dave

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    Posted
  • Location: Solihull, WestMidlands, 121m asl -20 would be nice :-)
  • Weather Preferences: Cold and Snow -20 would be nice :)
  • Location: Solihull, WestMidlands, 121m asl -20 would be nice :-)
    22 hours ago, knocker said:

    Further to the video

     

    Thankyou knocker in your continued efforts in finding very interesting articles like that, I found the video very informative especially the slowing of the gulf stream.....will it collapse altogether only time and what humanity does will tell.....and for the UK :cold:

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    Posted
  • Location: Surrey and SW France.
  • Location: Surrey and SW France.

    Just going to divert a wee bit with an interesting factoid for @claret047

    From the Wunderground blog.

    Nicole is venturing awfully far north for a hurricane
    Don’t look now, but Hurricane Nicole is making a run for Greenland. Nicole regained hurricane strength on Saturday, the first Atlantic storm to cross the hurricane threshold at least three times in its life since Hurricane Tomas in 2010 (thanks to Phil Klotzbach at Colorado State University for researching this statistic and to wunderground member Oxfordvalley for updating it]. Nicole has stubbornly retained its warm-core characteristics well north of the tropics, making it to 41°N as of 5 am EDT Monday. Nicole was heading north-northeast at about 9 mph and should accelerate in that direction. Eventually, Nicole will become a cold-core system, although that transition may happen extremely far to the north. The National Hurricane Center predicts that Nicole will become a post-tropical cyclone by Tuesday. However, a phase-space diagram produced by Robert Hart (Florida State University) for Nicole on Sunday, October 16, suggested that Nicole would remain a warm-core system (though increasingly asymmetric) until Thursday. On Thursday morning, the NHC forecast has Nicole as a post-tropical cyclone located between Greenland and Iceland, less than 70 miles from the Arctic Circle. Even then, Nicole should still be a powerful storm, with a surface pressure below 970 millibars and peak winds on the order of 60 mph. After Nicole finally dissipates somewhere near Greenland, its core of warm, moist air will continue into the Arctic, where the extent of sea ice is at its lowest mid-October level for any year on record except 2007 and 2012.

    https://www.wunderground.com/blog/JeffMasters/comment.html?entrynum=3482

    The latest phase space diagram showing still borderline warm core very far north.

    1.phase1.png

    http://moe.met.fsu.edu/cyclonephase/gfs/fcst/index.html 

     

     

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    Posted
  • Location: Springfield, Chelmsford, Essex 30Mtr ASL
  • Weather Preferences: snowy or sunny but not too hot!
  • Location: Springfield, Chelmsford, Essex 30Mtr ASL

    Thanks Nouska,

    A very interesting read indeed. Thank you very much.

    Kind Regards

    Dave

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    • 4 weeks later...
    Posted
  • Location: Netherlands close to the coast
  • Location: Netherlands close to the coast

    The cold blob seems to be getting smaller and the North Pacific is getting very cold, that good for us right? 

     

     

    anomnight.11.10.2016.gifanomnight.10.10.2016.gif

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    Posted
  • Location: Solihull, West Midlands. - 131 m asl .
  • Weather Preferences: Sun, Snow and Storms
  • Location: Solihull, West Midlands. - 131 m asl .
    3 hours ago, ArHu3 said:

    The cold blob seems to be getting smaller and the North Pacific is getting very cold, that good for us right? 

     

     

    anomnight.11.10.2016.gifanomnight.10.10.2016.gif

    ArHu..

    Interesting trends there.....

    For the first time for a couple of years we appear to have more surface sea water below average than above.

    Could this be the cooling promised by La Nina. I understand not directly?

    MIA

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    Posted
  • Location: New Forest (Western)
  • Weather Preferences: Fascinated by extreme weather. Despise drizzle.
  • Location: New Forest (Western)

    An exceptionally strong jet stream in he Pacific has produced extensive mixing up of cold waters from depth, in the same manner as deep cyclonicity gave rise to the N Atlantic cold pool of 2014-16.

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    Posted
  • Location: Leeds/Bradford border, 185 metres above sea level, around 600 feet
  • Location: Leeds/Bradford border, 185 metres above sea level, around 600 feet

    -PDO on the way. Good for the AO in my opinion. 

     

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    Posted
  • Location: New Forest (Western)
  • Weather Preferences: Fascinated by extreme weather. Despise drizzle.
  • Location: New Forest (Western)
    1 hour ago, summer blizzard said:

    -PDO on the way. Good for the AO in my opinion. 

     

    PDO%20PositiveAndNegative.gif

    sst.daily.anom_sm.gif

    I'm afraid (in light of your opinion with respect to the AO) it's actually a strong positive PDO configuration that's evolved.

    That's the thing about these indexes that are bipolar or tripolar; they can be counter-intuitive at first glance.

    The probable southward shift in the Aleutian Low is a useful consequence when you have weak ENSO forcing, though.

     

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    Posted
  • Location: Netherlands close to the coast
  • Location: Netherlands close to the coast
    On 11/18/2016 at 13:49, Singularity said:

    PDO%20PositiveAndNegative.gif

    sst.daily.anom_sm.gif

    I'm afraid (in light of your opinion with respect to the AO) it's actually a strong positive PDO configuration that's evolved.

    That's the thing about these indexes that are bipolar or tripolar; they can be counter-intuitive at first glance.

    The probable southward shift in the Aleutian Low is a useful consequence when you have weak ENSO forcing, though.

     

    this is historic pdo data, the long negative pdo period seems to coincide with the medieval warm period en de positive period with the little ice age, it's almost a perfect match https://en.wikipedia.org/wiki/Pacific_decadal_oscillation#/media/File:PDO1000yr.svg

    Edited by ArHu3
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    Posted
  • Location: New Forest (Western)
  • Weather Preferences: Fascinated by extreme weather. Despise drizzle.
  • Location: New Forest (Western)
    3 hours ago, ArHu3 said:

    this is historic pdo data, the long negative pdo period seems to coincide with the medieval warm period en de positive period with the little ice age, it's almost a perfect match https://en.wikipedia.org/wiki/Pacific_decadal_oscillation#/media/File:PDO1000yr.svg

    Now that is an interesting curiosity! :)

    I've not researched any possible link at all so I can't weigh in one way or the other on that.

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    Posted
  • Location: Leeds/Bradford border, 185 metres above sea level, around 600 feet
  • Location: Leeds/Bradford border, 185 metres above sea level, around 600 feet
    On 11/18/2016 at 12:49, Singularity said:

    PDO%20PositiveAndNegative.gif

    sst.daily.anom_sm.gif

    I'm afraid (in light of your opinion with respect to the AO) it's actually a strong positive PDO configuration that's evolved.

    That's the thing about these indexes that are bipolar or tripolar; they can be counter-intuitive at first glance.

    The probable southward shift in the Aleutian Low is a useful consequence when you have weak ENSO forcing, though.

     

    Ah. I had originally thought that the northern warm anomolies could be ignored due to a lack of ice however it does appear from your charts that i was thinking everything too far south. 

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    Posted
  • Location: Netherlands close to the coast
  • Location: Netherlands close to the coast

    A warm blob is starting to form on the US east coast, what would that mean for us?

     

    anomnight.11.21.2016.gif

     

    edit:from the danes 2 days later, wow goodbye cold blob hello warm blob:

     

    satanom.gbl.d-00.png

    Edited by ArHu3
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