Mooie samenvatting vond ik hier http://forum.netweather.tv/topic/67790-model-analysts-discussion/page__st__51
Tevens een handige beschrijving van de output van alle modellen van de avond ('s morgens trouwens ook!)
The output today shows a few more glimmers of hope for cold weather fans especially the GFS which amplifies that ridge and allows a brief colder shot from the north:
http://www.wetterzentrale.de/pics/Rtavn2401.png
Again though this is in FI and we've got to be careful that we're not continually chasing the pot of gold at the end of the rainbow, ie interesting output remains marooned at 240hrs!
However this chart is plausible if the mid Atlantic ridge can get far enough north and west, and this is the big question that remains. We have talked quite alot over the last few days about the MJO and it's possible effect on the patterns over Europe, normally the background La Nina makes it difficult for the MJO to remain strong and move through its phases, if you look at the composite for phase 7 in a non La Nina winter you get this:
http://raleighwx.americanwx.com/MJO/DJFPhase7.gif
But with a background La Nina winter which we have its generally more like this:
http://raleighwx.americanwx.com/MJO/LaNinagt1Phase7.gif
I don't really buy this second composite because of the way the atmosphere has generally behaved during this winter, we generally have seen more amplification than would be expected with the La Nina so I'm happy to go along with a more middle ground solution.
So more amplified but not as good as that first composite seems a sensible way forward.
Looking at the key timeframes in terms of chances for a colder shot into the UK, well although its likely to turn colder after this weekend this will be with high pressure close by so no chance of any snow.
Now this brings me to tonights ECM and we're once again looking at the amplification of troughing over the eastern USA in my first key timeframe around 168hrs and here we begin to see the ECM and GFS diverge with their upstream patterns, although the GFS amplifies that eastern USA trough it's much later to do this and this is where perhaps the MJO signal is being picked up differently by both models.
The eastern USA trough can be thought of as a magnet, the more this amplifies and the more it digs south into the west Atlantic the better pull on that high near the UK which allows that low to drop south around the ridge.
I expect the later part of the ECM output from 192hrs will cause alot of debate but its 12hrs run is a huge departure from its earlier 00hrs run and we should bear in mind its recent Russian High obsession especially with its 12hrs outputs. For this reason I would be very dubious of it at this timeframe.
So overall some more interest this evening and I think a decent chance of a colder shot from the north, although more a cold snap rather than anything longer term, in terms of the expected mass excitement in the forum regarding the ECM there is a chance that any ridge might topple towards Scandi giving a brief ne flow but I expect troughing to remain in Scandi.
The ECM IMO is a very unlikely solution with its sudden December memories revisited! as everyone knows I would love it to verify and be on the right trend but for the timebeing for me it's a non starter.
Tevens een handige beschrijving van de output van alle modellen van de avond ('s morgens trouwens ook!)
The output today shows a few more glimmers of hope for cold weather fans especially the GFS which amplifies that ridge and allows a brief colder shot from the north:
http://www.wetterzentrale.de/pics/Rtavn2401.png
Again though this is in FI and we've got to be careful that we're not continually chasing the pot of gold at the end of the rainbow, ie interesting output remains marooned at 240hrs!
However this chart is plausible if the mid Atlantic ridge can get far enough north and west, and this is the big question that remains. We have talked quite alot over the last few days about the MJO and it's possible effect on the patterns over Europe, normally the background La Nina makes it difficult for the MJO to remain strong and move through its phases, if you look at the composite for phase 7 in a non La Nina winter you get this:
http://raleighwx.americanwx.com/MJO/DJFPhase7.gif
But with a background La Nina winter which we have its generally more like this:
http://raleighwx.americanwx.com/MJO/LaNinagt1Phase7.gif
I don't really buy this second composite because of the way the atmosphere has generally behaved during this winter, we generally have seen more amplification than would be expected with the La Nina so I'm happy to go along with a more middle ground solution.
So more amplified but not as good as that first composite seems a sensible way forward.
Looking at the key timeframes in terms of chances for a colder shot into the UK, well although its likely to turn colder after this weekend this will be with high pressure close by so no chance of any snow.
Now this brings me to tonights ECM and we're once again looking at the amplification of troughing over the eastern USA in my first key timeframe around 168hrs and here we begin to see the ECM and GFS diverge with their upstream patterns, although the GFS amplifies that eastern USA trough it's much later to do this and this is where perhaps the MJO signal is being picked up differently by both models.
The eastern USA trough can be thought of as a magnet, the more this amplifies and the more it digs south into the west Atlantic the better pull on that high near the UK which allows that low to drop south around the ridge.
I expect the later part of the ECM output from 192hrs will cause alot of debate but its 12hrs run is a huge departure from its earlier 00hrs run and we should bear in mind its recent Russian High obsession especially with its 12hrs outputs. For this reason I would be very dubious of it at this timeframe.
So overall some more interest this evening and I think a decent chance of a colder shot from the north, although more a cold snap rather than anything longer term, in terms of the expected mass excitement in the forum regarding the ECM there is a chance that any ridge might topple towards Scandi giving a brief ne flow but I expect troughing to remain in Scandi.
The ECM IMO is a very unlikely solution with its sudden December memories revisited! as everyone knows I would love it to verify and be on the right trend but for the timebeing for me it's a non starter.
„Et nul ne se connait tant qu'il n'a pas souffert, „C'est une dure loi, mais une loi suprème, „Vieille comme le monde et la fatalité, „Qu'l nous faut du malheur regevoir le baptéme, ~Et qu'a ce triste prix tout doit étre acheté. „Les moissons pour murir out besoin de rosée, „Pour vivre et pour sentir l'homme a besoin de pleura, „La joie a pour symbole une plante brisée, „Humide encore de pluie et couverte de fleurs."
