UKMO also looking very good, and the NAVGEM. 

BTW Ive really tried to post in charts, but I just can't seem to make them clickable. I don't think the URLs are invalid. If the unclickable nature is the only issue, then I will try and adress it; but it isn't despearately important. I'd be very concerned though if my links actually were ending up on 404 pages. 

Anyway, the events seem to have remakably panned out in much the way the models were suggesting over the last week. The deep high over the bearing, has produced strong WAA into the pacific arctic, promoting high pressure over northern canada (rather than greenland as originally thought). So now the HP over canada is merging with the high from the atlantic, as is to be expected with northern blocking about. The low heights over greenland are becoming less of an issue aswell with WAA now on our side. So the route was pretty indirect, but the results are pretty much the same. If the bearing high had directly merged with the greenland high instead of taking a more indirect route, then I would have expected the cold spell to have been seen on the models a good 3 or 4 days ealier perhaps. Anyway once the blocking reaches western greenland, the trough over the UK will introduce colder air from the NW pretty quickly. The WAA over alaska is also progged to continue, and the uppers are extremely warm over northern canada, with pacific winds even bringing heavy rain to alaska. My guess is, that this should stop any spoiler lows from developing from the PV. The weakened PV that is left in canada would be only capable of producing much weaker lows in the northern subtropics and southern temperate latitudes. Despite this, the jetstream is going to remain reasonably flat over our part of the world, which is slightly paradoxical. I think this corresponds to a very weak jetstream that will run just south of the UK. Given a height rise over greenland we would expect it to become less flat over the western atlantic, however a flat jet in the UK will cause stuff to come our way, abeilt slowly. So perhaps slider lows and an eventual collapse of the block, which would either become restablished if the WAA continues over N canada, or disintegrate into zonality if it doesn't (I was thinking that a flatish jetstream south of the UK could possibly lead to retrogression of HP to scandanavia, however this doesn't seem too plausible at the moment since thats basically where the PV is). 

However I do notably disagree with people on here that say the cold snap will be short lived. I would expect a good 5 days at the least. 

Originally Posted by: NickR 

UKMO also looking very good, and the NAVGEM. 

BTW Ive really tried to post in charts, but I just can't seem to make them clickable. I don't think the URLs are invalid. If the unclickable nature is the only issue, then I will try and adress it; but it isn't despearately important. I'd be very concerned though if my links actually were ending up on 404 pages. 

Anyway, the events seem to have remakably panned out in much the way the models were suggesting over the last week. The deep high over the bearing, has produced strong WAA into the pacific arctic, promoting high pressure over northern canada (rather than greenland as originally thought). So now the HP over canada is merging with the high from the atlantic, as is to be expected with northern blocking about. The low heights over greenland are becoming less of an issue aswell with WAA now on our side. So the route was pretty indirect, but the results are pretty much the same. If the bearing high had directly merged with the greenland high instead of taking a more indirect route, then I would have expected the cold spell to have been seen on the models a good 3 or 4 days ealier perhaps. Anyway once the blocking reaches western greenland, the trough over the UK will introduce colder air from the NW pretty quickly. The WAA over alaska is also progged to continue, and the uppers are extremely warm over northern canada, with pacific winds even bringing heavy rain to alaska. My guess is, that this should stop any spoiler lows from developing from the PV. The weakened PV that is left in canada would be only capable of producing much weaker lows in the northern subtropics and southern temperate latitudes. Despite this, the jetstream is going to remain reasonably flat over our part of the world, which is slightly paradoxical. I think this corresponds to a very weak jetstream that will run just south of the UK. Given a height rise over greenland we would expect it to become less flat over the western atlantic, however a flat jet in the UK will cause stuff to come our way, abeilt slowly. So perhaps slider lows and an eventual collapse of the block, which would either become restablished if the WAA continues over N canada, or disintegrate into zonality if it doesn't (I was thinking that a flatish jetstream south of the UK could possibly lead to retrogression of HP to scandanavia, however this doesn't seem too plausible at the moment since thats basically where the PV is). 

However I do notably disagree with people on here that say the cold snap will be short lived. I would expect a good 5 days at the least. 

Originally Posted by: NickR