Going foward, I continue to see the wind signal to favour a phase 1-2 type orbit of the Global Wind Oscillation (mean ridge tendency in the North Atlantic) driven by continued falls in angular momentum. This is very likely to maintain the mean trough over Scandinavia, with the UK on the western most extent and cold air being advected down the flank. In my last posting the suggestion was for the mean ridge to be further east but I'm happy to go along with the ridge and trough being further west. Current thrust of NWP suggests air temperatures between 2C and 4C below normal for a 7-14 day period. The GFS idea of breaking the mean ridge (on a sustained basis is totally wrong IMO and tonight's 12z ECM ensemble mean start to rebuild the ridge in the Atlantic keeping the trough (and colder air) to our east in position and only slowly filling.
The blocking structure to our north is currently modelled to shift towards the Canadian Arctic. A consequent reduction in heights over Greenland is anticipated and this will also put pressure on the trough over the western Atlantic to migrate eastwards towards north-west Europe (GFS very keen on this). The presence of a down-welling westerly wave in the low stratosphere (ahead of the predicted warming) is of concern in terms of reducing blocking potential in the mid January timeframe.
The longer term modelling issue is whether the upper trough over the western Atlantic can migrate towards the UK underneath the mean ridge and merge with the Scandinavian trough. As per last few months, this has been modelled but invariably trough disruption ensues in the Atlantic. I can see some idea for the trough disruption mid January to flicker hopes of height rises towards Scandinavia. However, if the trough disruption allows for a quick rebuid of the Atlantic ridge, this effectively kills the easterly by deflecting the airmass south-west as the atmosphere pivots around the developing ridge drawing winds from the north-east. The form pony and indeed continued low angular momentum base state firmly favour the latter.
Weatherwise, a return to colder conditions (although not of the same magnitude as December) looks a solid bet for most parts of the UK in the next 10-15 days. With the ridge in place to our west, precipitation amounts look to be generally below average and trending drier if and when the next trough disruption takes place mid month.
En verder
I think somewhere between BOM, ECM and UKM offers the best solution at t144 given global wind signals at present so the rationale would be that the GFS has just gone off on one.
What is noticeable is the modelling of the blocking ridge migrating towards Canada and lowering of heights over Greenland from the east. The longer term question looks to be where the next blocking evolution on our side of the hemipshere is going to be. GFS at present looking for something of a Euro High. I would be thinking more mid latitude.
The blocking structure to our north is currently modelled to shift towards the Canadian Arctic. A consequent reduction in heights over Greenland is anticipated and this will also put pressure on the trough over the western Atlantic to migrate eastwards towards north-west Europe (GFS very keen on this). The presence of a down-welling westerly wave in the low stratosphere (ahead of the predicted warming) is of concern in terms of reducing blocking potential in the mid January timeframe.
The longer term modelling issue is whether the upper trough over the western Atlantic can migrate towards the UK underneath the mean ridge and merge with the Scandinavian trough. As per last few months, this has been modelled but invariably trough disruption ensues in the Atlantic. I can see some idea for the trough disruption mid January to flicker hopes of height rises towards Scandinavia. However, if the trough disruption allows for a quick rebuid of the Atlantic ridge, this effectively kills the easterly by deflecting the airmass south-west as the atmosphere pivots around the developing ridge drawing winds from the north-east. The form pony and indeed continued low angular momentum base state firmly favour the latter.
Weatherwise, a return to colder conditions (although not of the same magnitude as December) looks a solid bet for most parts of the UK in the next 10-15 days. With the ridge in place to our west, precipitation amounts look to be generally below average and trending drier if and when the next trough disruption takes place mid month.
En verder
I think somewhere between BOM, ECM and UKM offers the best solution at t144 given global wind signals at present so the rationale would be that the GFS has just gone off on one.
What is noticeable is the modelling of the blocking ridge migrating towards Canada and lowering of heights over Greenland from the east. The longer term question looks to be where the next blocking evolution on our side of the hemipshere is going to be. GFS at present looking for something of a Euro High. I would be thinking more mid latitude.
„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."
