Good morning. Here is the report on the NWP output taken using the 12 midnight data on Friday December 20th 2013.
All models show very unsettled conditions up to Christmas with a new Low and fronts crossing NW Britain today with severe gales and heavy rain developing and sinking it subsequently SE over Southern areas tonight where it becomes slow moving and mild again later. Tomorrow sees colder and showery conditions finally reach the SE late in the day with Sunday being a very windy and showery day for all with the heaviest ones in the West and with wintry ones on Northern hills.
CHRISTMAS EVE looks likely to become very wet and potentially stormy as yet another storm system approaches NW Britain. Heavy rain and severe gales look likely for all before colder and clearer weather with squally showers in Westerly gales reach all but the SE by Christmas Eve night. CHRISTMAS DAY looks like very deep Low pressure will lie close to the North with a strong rather cold and showery Westerly flow delivering a lot of showers to Western and Northern coasts and hills with rather drier and brighter weather possible in the East with a little sunshine. BOXING DAY currently shows rather lighter Westerly winds but rather cold conditions across the UK. With pressure shown to be very low from all models troughs would bring showery outbreaks of rain and hill snow with the most likely places to receive these impossible to predict at this range but nowhere would likely be immune.
GFS then leads us out of Christmas and into the New Year with further storm systems repeatedly rushing across the Atlantic and passing the NW of Scotland maintaining the pattern of strong winds and rain in relatively mild conditions with spells of showery weather when it will be rather colder with some wintry showers over the hills of the north at least.
UKMO closes it's output with Boxing Day being an unsettled day with a trough crossing East giving enhanced showers, perhaps wintry on hills before drier and less showery weather moves in from the West late in the day.
GEM shows a cocktail of Low pressure systems encompassing the UK in the period up towards the New Year with plenty of scope for gales and heavy rain on each day with some brighter and colder moments in between.
NAVGEM ends the Christmas holiday period with an intense storm near SW England with severe gales and torrential rainfall possible in the South should it evolve with some snow possible on it's Northern flank while Northern areas remain rather chilly and showery.
ECM closes Christmas with another storm system up to the NW pushing SW'ly gales and heavy rain across all areas when it will become briefly milder again with the sunshine and shower mix returning again for a time as we approach New Years Eve. However, the embryonic signs of a new storm system to arrive over the New Year period is high on it's 10 day chart.
The GFS Ensembles show no shift whatsoever in maintaining the current pattern of Atlantic driven weather through the entire period with the mean temperatures for the run hugging the long term average throughout. Rainfall is again shown to be copious and troublesome at times with flooding issue a very likely proposition if this verifies.
The Jet Stream powering this pattern remains locked in situ with a short fluctuation South of the UK over Christmas before powering back NE across the British Isles again towards the New Year.
In Summary the pattern remains locked with a powerful Jet stream continuing to feed active storm systems close to NW Britain each giving their own bouts of gales and heavy rain in repeated doses. There will be some polar maritime incursions of air when showers could be heavy and wintry almost anywhere before milder weather returns on the next approaching storm. There looks unlikely to be any major pattern shift now this side of the New Year with the Jet Stream in 10 days time showing little significant signs of weakening or changing it's orientation. the net result of this sustained period will be the flooding that is likely to develop with time and this takes the headline away somewhat from the earlier risks of storm force winds over Christmas which thankfully looks to have receded somewhat on most recent model runs.
Martin G
Kilmersdon Radstock Bath Somerset