Sheikh Ma Nuggets
Tony Parks
Evening all,
Just back from roasting my gonads off in Greece - such a contrast to the weather which we get over in the UK! It's record heat in the Greek Islands too at the moment; they've never known anything like it - poor fudgers.
Anyway, if any of you want to really learn about how the movement of air in the upper atmosphere corresponds to pressure differentials at the surface, then I implore you to watch this brilliant video made by Chris Fawkes:
http://www.bbc.co.uk/news/uk-18876550
He articulates and illustrates very well the inter-reliant relationship and how 'upstream' (US / Canada) signals dictate the weather 4,000 miles away. It's this governing principle by which it pays to observe the weather which is transiting off the Eastern seaboard of the United States.
Indeed the good news is that there is a much awaited pattern change in operation. But how long can this pattern be sustained? Well, it all really depends on AAM (Atmospheric Angular Momentum) and you'd want this to remain a high value, so that the jet stream retains its northerly regression. In the short-term (10 days, using these indices) AAM is conducive, which correlates to the forecasted warming pattern. However, in the medium range (10-20 days) AAM is forecast to rapidly drop; so, less conducive to the high pressure build, and more likely for - yet again - southern progression of the jet stream. It's not an absolute relationship though, merely atmospheric conditions which tend to control the 60:40 variations in calculations.
Long-term pressure anomalies do, however, suggest a mean anomaly over NW Europe though August & September. What does this mean? In simple terms: a signal that something more resembling summer will be dominant, indeed the classic - and now fairly commonplace for the UK - "Indian Summer". It's been a very disappointing summer weather-wise, but unfortunately this is often the case for Northern Europe when there is an ENSO transition in the southern oceans. Too much change in SSTs tends to alter otherwise settled patterns as energy is continually displaced; moderation is the key to sustainability.
I'm already looking towards the winter, and how the prevailing patterns we're experiencing now may be extrapolated forward 6mths or so. The models are continually suggesting pressure rises over Greenland, which is conducive to cold feeds of air from both the northern and eastern sectors. Early days, but - to me - this suggests we may be in for another cold winter; indeed having viewed the latest CFS forecast, you can see a very pronounced cold temperature anomaly through into April of next year: http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/lanina/images3/euT2mProbSea.gif CFS also propagates below average precipitation, which suggests a high pressure dominated weather pattern. To note: it's this high pressure blocking which resulted in those very harsh winters we've been experiencing. But we're talking 6mths+ away here, just gives you an indication as to how - even at this range - you can begin to form an opinion as to prevailing patterns many months down the line.
Just back from roasting my gonads off in Greece - such a contrast to the weather which we get over in the UK! It's record heat in the Greek Islands too at the moment; they've never known anything like it - poor fudgers.
Anyway, if any of you want to really learn about how the movement of air in the upper atmosphere corresponds to pressure differentials at the surface, then I implore you to watch this brilliant video made by Chris Fawkes:
http://www.bbc.co.uk/news/uk-18876550
He articulates and illustrates very well the inter-reliant relationship and how 'upstream' (US / Canada) signals dictate the weather 4,000 miles away. It's this governing principle by which it pays to observe the weather which is transiting off the Eastern seaboard of the United States.
Indeed the good news is that there is a much awaited pattern change in operation. But how long can this pattern be sustained? Well, it all really depends on AAM (Atmospheric Angular Momentum) and you'd want this to remain a high value, so that the jet stream retains its northerly regression. In the short-term (10 days, using these indices) AAM is conducive, which correlates to the forecasted warming pattern. However, in the medium range (10-20 days) AAM is forecast to rapidly drop; so, less conducive to the high pressure build, and more likely for - yet again - southern progression of the jet stream. It's not an absolute relationship though, merely atmospheric conditions which tend to control the 60:40 variations in calculations.
Long-term pressure anomalies do, however, suggest a mean anomaly over NW Europe though August & September. What does this mean? In simple terms: a signal that something more resembling summer will be dominant, indeed the classic - and now fairly commonplace for the UK - "Indian Summer". It's been a very disappointing summer weather-wise, but unfortunately this is often the case for Northern Europe when there is an ENSO transition in the southern oceans. Too much change in SSTs tends to alter otherwise settled patterns as energy is continually displaced; moderation is the key to sustainability.
I'm already looking towards the winter, and how the prevailing patterns we're experiencing now may be extrapolated forward 6mths or so. The models are continually suggesting pressure rises over Greenland, which is conducive to cold feeds of air from both the northern and eastern sectors. Early days, but - to me - this suggests we may be in for another cold winter; indeed having viewed the latest CFS forecast, you can see a very pronounced cold temperature anomaly through into April of next year: http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/lanina/images3/euT2mProbSea.gif CFS also propagates below average precipitation, which suggests a high pressure dominated weather pattern. To note: it's this high pressure blocking which resulted in those very harsh winters we've been experiencing. But we're talking 6mths+ away here, just gives you an indication as to how - even at this range - you can begin to form an opinion as to prevailing patterns many months down the line.
