In Depth Model Discussion, Analysis and Summaries

[in the vale]

http://www.bbc.co.uk/news/science-environment-17143269

I know this has been discussed before, but the causal link appears to be more apparent in this latest study. Can't see the actual data (the full paper is available here for $10 - http://www.pnas.org/content/early/2012/02/17/1114910109.full.pdf+html?sid=9ba19f8f-76de-4bce-b16b-4fe0977c350b) , but could the latest upward indicated swing possibly go some way to explain the shape of the northern jet this winter compared to the last two? I know this is possibly a simplification (given other factors), but if the influence is strong would it not be a key factor?

[Glacier Point]

More sustained loss of westerlies across both hemispheres and total angular momentum has crashed to strong Nina territory:

The Global Wind Oscillation is registering a phse 2-3 type orbit (no sign of an appreciable impact of the MJO (tropical component)) and this teleconnects well with an anomalous mid latitude ridge centred over NW Europe.

Since January, relative angular momentum has gone from around +2 to -3 SD. For spring months which saw a reversal similar to this in net balance of zonal winds, composites are very consistent with a prolonged anticyclonic phase of weather (NB ridge probably slight;y further west than shown here).

May possibly a little more unsettled, but March and April dry. Not good for those looking for rainfall.

[damianslaw]

March and April are traditionally dry months in this country when the atlantic is at its most quietest - ridges and anticylones have a habit of sticking around a long time - so not too surprised to see GP's predictions - however, we have been in a very lengthy dry period which goes back to Dec 2009 with notably rainy periods unfortunately confined to the summer. Interesting to see how this dry period came on the back of the record wet November 2009.

Laws of averages and probability and everything should suggest a return to at least a more average sustained period of rainfall sometime before the year is out - whether this starts in late spring, summer, autumn or early winter remains to be seen - but I would be very surprised if 2012 ends up as dry as 2011.

The reason for the lengthy dry period in the south at least has all been due to the very weak westerlies - an anomalous strong heights at first to our north during 2010 but since early last year to our south.

Since Dec 2010 our weather most of the time has been exceptionally non-descript, mild and benign being the two words which spring to mind. If we see a quiet dry March and April suspect this forum will go dead.

[Alex]

More sustained loss of westerlies across both hemispheres and total angular momentum has crashed to strong Nina territory:

The Global Wind Oscillation is registering a phse 2-3 type orbit (no sign of an appreciable impact of the MJO (tropical component)) and this teleconnects well with an anomalous mid latitude ridge centred over NW Europe.

Since January, relative angular momentum has gone from around +2 to -3 SD. For spring months which saw a reversal similar to this in net balance of zonal winds, composites are very consistent with a prolonged anticyclonic phase of weather (NB ridge probably slight;y further west than shown here).

May possibly a little more unsettled, but March and April dry. Not good for those looking for rainfall.

I see the components for spring are very much aligned to some pretty bad summers, 2007 is the modern one that springs to mind. Do you think this upcoming spell will mean bad news for the summer GP?

[Glacier Point]

A touch too early to make a call Alex, although IF angular momentum remains low, then the ingredients would be there for another duff summer. However, a number of factors are there which may force angular momentum upwards, not least a predicted weak El Nino transition. The PDO remains negative though which will favour a more 1950s type summer.

The wildcard here is solar activity. After a quiet period, the sun sprang to life last night and we are due a period of enhanced activity as we head into the solar max which can only be a good think for those looking for a warm, dry summer.

[Weather Wizard]

A touch too early to make a call Alex, although IF angular momentum remains low, then the ingredients would be there for another duff summer. However, a number of factors are there which may force angular momentum upwards, not least a predicted weak El Nino transition. The PDO remains negative though which will favour a more 1950s type summer.

The wildcard here is solar activity. After a quiet period, the sun sprang to life last night and we are due a period of enhanced activity as we head into the solar max which can only be a good think for those looking for a warm, dry summer.

Sorry for my ignorance but what were the summers in the 1950's like

Thanks

[picog]

Sorry for my ignorance but what were the summers in the 1950's like

Thanks

Cool/cold and wet— unsummer-like.

[ANYWEATHER]

I see the components for spring are very much aligned to some pretty bad summers, 2007 is the modern one that springs to mind. Do you think this upcoming spell will mean bad news for the summer GP?

There seems to be a strong correlation between Warm /dry Springs and Poor Summers. Just look at the Summers since 2007. very poor on a whole, although 2011 did see a dry year in Central and Eastern England [scotland, having its wettest Summer on Record!] which is still ongoing and looking at the latest models shows this continuing for at least a while yet!

[Thundery wintry showers]

Sorry for my ignorance but what were the summers in the 1950's like

Thanks

Generally speaking they were (1954 and 1956 were extreme cases) but there were exceptions. 1955 and 1959 were pretty hot and sunny (with a hot sunny extended summer in the case of 1959, extending well into October), also June 1957 had record sunshine totals in some regions of the country. The really cold dull wet decade was the 1960s.

If we get a dry spring then summer may well be a choice of two evils- either a washout or hosepipe bans! An "active" summer on the convection front may help alleviate the water shortages without requiring an outright washout but on the other hand short sharp downpours don't replenish the water table as effectively as persistent moderate rain.

Not entirely sure about the correlations between warm/dry springs and cool/wet summers. The relationship has been followed consistently since 2007, but it wasn't followed in 1893 (a record-breaking dry spring followed by quite a hot summer), 1990 or 2003. The springs of 1976 and 1995, leading into those scorching summers, were also quite dry in many places.

All of the signals do point towards a dry start to spring with high pressure firmly in charge.

[Scorcher]

The wildcard here is solar activity. After a quiet period, the sun sprang to life last night and we are due a period of enhanced activity as we head into the solar max which can only be a good think for those looking for a warm, dry summer.

This is interesting, I have been puzzled recently with all the stories about solar activity and coronal mass ejections leading to the Aurora Borealis being visible unusually far south and yet there have been members saying that the sun is very quiet. Can someone enlighten me as to how this can be happening but the sun can still be quiet?

[Robbie Garrett]

This is interesting, I have been puzzled recently with all the stories about solar activity and coronal mass ejections leading to the Aurora Borealis being visible unusually far south and yet there have been members saying that the sun is very quiet. Can someone enlighten me as to how this can be happening but the sun can still be quiet?

Hello,

I've read up on it so can provide you with some information regarding that, in short.. the sun has cycles, a bit like the earth has cycles with some of it's weather. Every 11 years or so, sometimes 9 years (at shortest between Maximum and Minimum (vise versa)) the Sun will have more sun spots, solar flares, CMEs etc during a Maximum and less during a minimum.

Basically this maximum at the moment, hasn't actually happened (Or was meant to happen in 2010/11) but this has now been forecast to be 2013/14 but they cannot be sure for certain because the sun is fairly quite than it should be (11 years after the last maximum)

I hope that makes sense.

Kind Regards,

R..

[BLAST FROM THE PAST]

This is interesting, I have been puzzled recently with all the stories about solar activity and coronal mass ejections leading to the Aurora Borealis being visible unusually far south and yet there have been members saying that the sun is very quiet. Can someone enlighten me as to how this can be happening but the sun can still be quiet?

Sunspot 1429 is a powerful and active sunspot, probably largest since 2005. Its got nothing to do with sunspot number/ cycle activity though, as this remains low and on par with cycle 5 [Dalton Minima territory]. One large sunspot with large solar flares does not make an active cycle. Take a look at Landscheidt or Spaceweather sites for more info.....lots for you to read into. Here is example of current cycle activity compared to last three cycles...curent one is purple.

BFTP

[

Edited March 13, 2012 by BLAST FROM THE PAST

[lorenzo]

Re Solar Activity.

Some bookmarks I have kept from various sources and other members on here..

http://sc25.com/inde...68&linkbox=true

http://solarscience....v/predict.shtml

http://www.landscheidt.info/?q=node/50

For closer 'model output' analysis there is an excellent thread in the Space and Science Section update regularly by George with Nasa Space Weather analysis..

There have been climate studies on Sun cycles on Polar vortex and Stratosphere centred around Svalbard iirc - found a paper earlier in Winter but have not saved it - hope these are useful..

Edit - must have been yourself Blast !

Edited March 13, 2012 by lorenzo

[Robbie Garrett]

Having a good read of some those links above, if it's believed that Solar Cycle 25 is as low as predicted it means we wont likely see a hot/warm summer in our lifetimes again!!

[Scorcher]

Thanks for all the information, very interesting indeed.

[Robbie Garrett]

What was the condition's like leading up to Summer 2003??

A touch too early to make a call Alex, although IF angular momentum remains low, then the ingredients would be there for another duff summer. However, a number of factors are there which may force angular momentum upwards, not least a predicted weak El Nino transition. The PDO remains negative though which will favour a more 1950s type summer.

The wildcard here is solar activity. After a quiet period, the sun sprang to life last night and we are due a period of enhanced activity as we head into the solar max which can only be a good think for those looking for a warm, dry summer.

[BLAST FROM THE PAST]

http://iceagenow.info/wp-content/uploads/2012/03/sunspot_cycle_thru_feb_2012

Thanks for links Lorenzo.

Above is just to show that big flares do not make an active sun. It is very quiet at the moment

BFTP

[La Bise]

So I'm reading Matt Hugo about a strong signal for MJO to enter phase 6/7 by early April, any thoughts for you chaps?

[Alex]

So I'm reading Matt Hugo about a strong signal for MJO to enter phase 6/7 by early April, any thoughts for you chaps?

From memory I believe this means a high to the west or southwest of us, so a westerly or northwesterly wind is favoured.

[La Bise]

Seems to tie up pretty well with Meto 16-30 dayer actually.

[coldwinter]

Possible pattern change early april as MJO looks to enter phase 6/7. ECM 32 dayer signals a change to colder more unsettled conditions in april, with possibily north or north east winds.

Latest EC 32 continues the dry, settled and mild signal until the end of March, but with a sig pattern change early April......high pressure becomes a feature to the W of the UK and temps drop below avg, with rainfall near or above avg & potential N or NE'ly winds

Winter to return anyone?

Bring it on.

Ryan.

[johnholmes]

Possible pattern change early april as MJO looks to enter phase 6/7. ECM 32 dayer signals a change to colder more unsettled conditions in april, with possibily north or north east winds.

Latest EC 32 continues the dry, settled and mild signal until the end of March, but with a sig pattern change early April......high pressure becomes a feature to the W of the UK and temps drop below avg, with rainfall near or above avg & potential N or NE'ly winds

Winter to return anyone?

Bring it on.

Ryan.

see my post in the model thread in response to the same post you made as the one here

[jethro]

Came across these and thought some here may find them interesting:

Impact of sea ice cover changes on the Northern Hemisphere atmospheric winter circulation

http://www.tellusa.net/index.php/tellusa/article/view/11595/pdf

Arctic warming, increasing snow cover and widespread boreal winter cooling

http://iopscience.iop.org/1748-9326/7/1/014007/pdf/1748-9326_7_1_014007.pdf

[syed2878]

Thanks for the links.

[Glacier Point]

Reanalysis of the last 30 days longwave pattern is very consistent with the anlogues for low angular momentum and supports the idea of a blocking ridge centred close to the UK:

Since early February, relative angular momentum has been very low reflective of a low angular momentum base state. However, the last week or so has seen something of a significant change and we will need to monitor this to see whether this is a game changer and will ultimately signal the demise of an ocean-atmospheric coupling for La Nina.

The MJO has been the trigger, moving through phases 3-4-5-6 and has generated significant increase in westerly winds across the tropics. Tendency in relative angular momentum spiked last week at over +4SD, and, with poleward transfer in the next few weeks, every chance that we'll continue to see angular momentum and tropical convection reflect a more neutral or even developing El Nino state. Certainly the MJO forecasts (ECM here) seem to suggest that the wave will remain in the western Pacific (phases 6-7) which should prevent a widespread fall in angular momentum.

This should keep the global wind oscillation in a phase 4-5-6 type orbit during April. Composites below:

..suggesting our mean ridge position to shift further west and north-west for a large part of April allowing more of a cooler north-westerly airflow. Cooler and showery weather type, although I suspect with the AO remaining positive, we might have less in the way of convection than these composites are suggesting with the high pressure closer to the UK.

Edited March 20, 2012 by Glacier Point