hij heeft weer van zich laten horen. Hij kreeg er heel wat vragen en vooral kritiek, eigenlijk voor een groot deel terecht want hij stelde zich voor als een zeer ervaren weersvoorspeller maar uiteindelijk bleek het om zijn vader te gaan.
Enfin, ik post het hier even maar ik moet het in feite zelf allemaal nog eens doornemen.
Voor zij die het oorspronkelijke bericht gemist hebben, verwijs ik naar de link onderaan.
Here is some of my methodology, if you have time to read it all.
By the way, the part about being a highly experienced weather forecaster- well okay, I share a lot of my knowledge from my father, who has been studying the charts for over 30 years. I suppose I should have made that more clear, although it was all a lot to have to put into a first post. However the MSc was a very intense course and certainly at the end of it I felt a million times more experienced in the understanding of meteorology than before I did the degree. I have been reading charts since my teens, probably for 8 years or so (and yes I used to get caught up with the GFS runs past 180 hours at first!) I'm still amazed I didn't find this site sooner; it is a brilliant site with so many great threads. I just wish I had more generous breaks at work,
I know experience does come with age, so I'm not going to pretend I'm the most experienced meteorologist around. All I'm trying to do is the best I can with all the knowledge that I have to offer and I hope that my first post wasn't intimidating to anyone.
I will discuss the pressure patterns of the last few months and how I feel they are very important to predicting the weather for this winter.
First of all let’s compare the jet stream in the North Atlantic on October 31st over the N Atlantic with other recent years.
http://www.wetterzentrale.de/archive/ra/2002/Rrea00220021031.gif
In 2002, there is little in the way of blocking over Europe and an active Atlantic with a southerly tracking jet.
http://www.wetterzentrale.de/archive/ra/2003/Rrea00220031031.gif
In 2003, southerly tracking lows but a very Active Atlantic, with any blocking to the north too far away to have any dominance on western Europe, which is followed by a very mild November.
http://www.wetterzentrale.de/archive/ra/2004/Rrea00220041031.gif
In 2004, another active Atlantic with a well defined jet stream in its normal tracking.
http://www.wetterzentrale.de/archive/ra/2005/Rrea00220051031.gif
In 2005, Scandinavia is exceptionally warm for the end of October and a very Active Atlantic again.
http://www.wetterzentrale.de/archive/ra/2006/Rrea00220061031.gif
In 2006 we have a noticeably different set up compared to recent years with a far more blocked regime and a less active Atlantic.
Compare with the rest of October:
http://www.wetterzentrale.de/archive/ra/2006/Rrea00120061001.gif
http://www.wetterzentrale.de/archive/ra/2006/Rrea00120061011.gif
http://www.wetterzentrale.de/archive/ra/2006/Rrea00120061021.gif
Notice the regular blocking over Greenland and again, a much more southerly tracking jet compared to recent Octobers. Of course, the warmth was due to a virtually persistent feed of south to south-easterly winds. Much of October had frequent northern blocking and as it was too early in the season, there was not enough cold air over western Russia and Scandinavia to produce a larger more stubborn area of high pressure, which can persist for several weeks over southerly tracking lows.
However, cold weather in Scandinavia at this time of year is not particularly important for winter, as very cold air can flood into this region rapidly from the Arctic, due to its very northerly latitude and its proximity to the Arctic Circle.
Now although Scandinavia is very mild at the moment, we have had a southerly tracking jet for a number of weeks now, which is of course a promising sign for northern blocking. What has been evident since September is the tendency for southerly winds with high pressure over the continent, bringing in abnormally prolonged spells of mild weather which were responsible for the very warm weather of this Autumn so far.
This type of set up in winter is rarely very mild and unless there is a southwesterly origin to these southerly airstreams they will usually bring fairly uneventful weather in the form of frost and fog and fairly cold weather in the south and mild weather in the north.
Now let’s take a look back at the trends from the winters of 2004-2005 and 2005-2006.
2004-2005 was a mild winter with a milder than average December and an unsettled and very mild January. However, by late February a blocked pattern developed and result in a well below average period from February 17th – March 15th. Had this blocking occurred a month earlier, it would have resulted in a much colder spell with more intense cold pooling over the continent, which just wasn’t around in the easterly spell of late February 2005.
2005-2006 was generally a rather settled winter and notably blocked at times, particularly in late November and late February. There were a number of occasions where very cold air over the continent flooded into Western Europe, however due to the position of the blocking the very cold air was unable to progress westwards.
In the late December 2005 easterly, high pressure did not expand westwards due to an active jet stream and as a result the high pressure was unable to join with the Greenland high. If this had happened it would have led to a secure northern latitude block and with a turbulent jetstream and would have caused severe winter weather from a polar continental versus a tropical maritime battle across the UK. Pressure was to low over Iceland for this to happen, which is why a large Greenland block is needed.
http://www.wetterzentrale.de/archive/ra/2005/Rrea00120051228.gif
I expect the trends of these last two winters to continue, but this time there will be much stronger blocking over Greenland which will become persistent due to the developing cold pool in this region which began to develop quite rapidly in October:
http://www.wetterzentrale.de/archive/ra/2006/Rrea00220061022.gif
http://www.wetterzentrale.de/archive/ra/2006/Rrea00220061025.gif
More blocking in this region will allow easterly airstreams to advect westwards and the continuing southerly track of these lows will lead to some very interesting weather events by December.
Obviously at this time I can only forecast the expected synoptics, temperatures and weather for the UK as a whole and I won't go into mesoscale meteorology yet. There are bound to be some people who miss out even in the most severe cold spells. This is a general forecast which paints a picture of what the country as a whole can expect. Eastern and northern coasts will of course see the most snow in a northerly and easterly wind.
The equations I use are for pattern matching and for short-term forecasting which I will again try to explain later when I find the time to post more on my methodology tomorrow or on Saturday.
Enfin, ik post het hier even maar ik moet het in feite zelf allemaal nog eens doornemen.
Voor zij die het oorspronkelijke bericht gemist hebben, verwijs ik naar de link onderaan.
Here is some of my methodology, if you have time to read it all.
By the way, the part about being a highly experienced weather forecaster- well okay, I share a lot of my knowledge from my father, who has been studying the charts for over 30 years. I suppose I should have made that more clear, although it was all a lot to have to put into a first post. However the MSc was a very intense course and certainly at the end of it I felt a million times more experienced in the understanding of meteorology than before I did the degree. I have been reading charts since my teens, probably for 8 years or so (and yes I used to get caught up with the GFS runs past 180 hours at first!) I'm still amazed I didn't find this site sooner; it is a brilliant site with so many great threads. I just wish I had more generous breaks at work,
I know experience does come with age, so I'm not going to pretend I'm the most experienced meteorologist around. All I'm trying to do is the best I can with all the knowledge that I have to offer and I hope that my first post wasn't intimidating to anyone.
I will discuss the pressure patterns of the last few months and how I feel they are very important to predicting the weather for this winter.
First of all let’s compare the jet stream in the North Atlantic on October 31st over the N Atlantic with other recent years.
http://www.wetterzentrale.de/archive/ra/2002/Rrea00220021031.gif
In 2002, there is little in the way of blocking over Europe and an active Atlantic with a southerly tracking jet.
http://www.wetterzentrale.de/archive/ra/2003/Rrea00220031031.gif
In 2003, southerly tracking lows but a very Active Atlantic, with any blocking to the north too far away to have any dominance on western Europe, which is followed by a very mild November.
http://www.wetterzentrale.de/archive/ra/2004/Rrea00220041031.gif
In 2004, another active Atlantic with a well defined jet stream in its normal tracking.
http://www.wetterzentrale.de/archive/ra/2005/Rrea00220051031.gif
In 2005, Scandinavia is exceptionally warm for the end of October and a very Active Atlantic again.
http://www.wetterzentrale.de/archive/ra/2006/Rrea00220061031.gif
In 2006 we have a noticeably different set up compared to recent years with a far more blocked regime and a less active Atlantic.
Compare with the rest of October:
http://www.wetterzentrale.de/archive/ra/2006/Rrea00120061001.gif
http://www.wetterzentrale.de/archive/ra/2006/Rrea00120061011.gif
http://www.wetterzentrale.de/archive/ra/2006/Rrea00120061021.gif
Notice the regular blocking over Greenland and again, a much more southerly tracking jet compared to recent Octobers. Of course, the warmth was due to a virtually persistent feed of south to south-easterly winds. Much of October had frequent northern blocking and as it was too early in the season, there was not enough cold air over western Russia and Scandinavia to produce a larger more stubborn area of high pressure, which can persist for several weeks over southerly tracking lows.
However, cold weather in Scandinavia at this time of year is not particularly important for winter, as very cold air can flood into this region rapidly from the Arctic, due to its very northerly latitude and its proximity to the Arctic Circle.
Now although Scandinavia is very mild at the moment, we have had a southerly tracking jet for a number of weeks now, which is of course a promising sign for northern blocking. What has been evident since September is the tendency for southerly winds with high pressure over the continent, bringing in abnormally prolonged spells of mild weather which were responsible for the very warm weather of this Autumn so far.
This type of set up in winter is rarely very mild and unless there is a southwesterly origin to these southerly airstreams they will usually bring fairly uneventful weather in the form of frost and fog and fairly cold weather in the south and mild weather in the north.
Now let’s take a look back at the trends from the winters of 2004-2005 and 2005-2006.
2004-2005 was a mild winter with a milder than average December and an unsettled and very mild January. However, by late February a blocked pattern developed and result in a well below average period from February 17th – March 15th. Had this blocking occurred a month earlier, it would have resulted in a much colder spell with more intense cold pooling over the continent, which just wasn’t around in the easterly spell of late February 2005.
2005-2006 was generally a rather settled winter and notably blocked at times, particularly in late November and late February. There were a number of occasions where very cold air over the continent flooded into Western Europe, however due to the position of the blocking the very cold air was unable to progress westwards.
In the late December 2005 easterly, high pressure did not expand westwards due to an active jet stream and as a result the high pressure was unable to join with the Greenland high. If this had happened it would have led to a secure northern latitude block and with a turbulent jetstream and would have caused severe winter weather from a polar continental versus a tropical maritime battle across the UK. Pressure was to low over Iceland for this to happen, which is why a large Greenland block is needed.
http://www.wetterzentrale.de/archive/ra/2005/Rrea00120051228.gif
I expect the trends of these last two winters to continue, but this time there will be much stronger blocking over Greenland which will become persistent due to the developing cold pool in this region which began to develop quite rapidly in October:
http://www.wetterzentrale.de/archive/ra/2006/Rrea00220061022.gif
http://www.wetterzentrale.de/archive/ra/2006/Rrea00220061025.gif
More blocking in this region will allow easterly airstreams to advect westwards and the continuing southerly track of these lows will lead to some very interesting weather events by December.
Obviously at this time I can only forecast the expected synoptics, temperatures and weather for the UK as a whole and I won't go into mesoscale meteorology yet. There are bound to be some people who miss out even in the most severe cold spells. This is a general forecast which paints a picture of what the country as a whole can expect. Eastern and northern coasts will of course see the most snow in a northerly and easterly wind.
The equations I use are for pattern matching and for short-term forecasting which I will again try to explain later when I find the time to post more on my methodology tomorrow or on Saturday.
"Koersen, dat is stampen en afzien tot ge niet meer weet van welke parochie ge zijt." (Briek Schotte)
