Good morning folks. Today is the shortest day and from today o the hours of daylight become slowly longer. So with that thought in mind here is my look at the NWP output based on the midnight outputs for today Saturday December 21st 2013.
All models continue to show very volatile conditions across the UK up to and over the Christmas period. A showers WSW flow shown today will be exacipated by an active squally trough sweeping East tonight following the final clearance of rain from the SE earlier in the day. Once passed temperatures will fall markedly as a colder westerly flow is shown to take hold with scattered showers and sunny spells tomorrow with most of the showers near Western coasts with some Eastern parts becoming dry. On Monday another powerful storm system close to the NW is shown to spread severe gales and loads of rain across the UK from the SW and it will become mild again especially in the South. By Christmas Eve this weather is shown to be replaced by colder and more showery conditions in the North and West filtering down into the SE later. Christmas Day then looks to be a colder, less windy and potentially showery day with some sheltered areas away from prevailing West winds perhaps seeing a dry day while areas in the West see showers, wintry on hills. Boxing Day looks like starting dry and cold for many away from Western areas with a frost and light winds for a time. Later in the day things go quickly downhill as the next Atlantic storm system approaches the UK from the West.
GFS then shows the run up to the New Year as remaining very unsettled and potentially stormy as further Low pressure brings rain and showers in off the Atlantic repeated over the New Year before things finally look like becoming less stormy and quieter especially across the South as the Jet stream moves North and takes the worst of the depression further North to affect the north far worse than the South by the end of the run.
UKMO closes it's run on the 27th with a new deep Low pressure out to the NW having spread mild and strong SW winds back across the UK with gales and heavy rain likely for all at times with severe gales in places.
GEM today also shows a continuing very unsettled period lasting up to and including the New Year as successive depressions deliver wind and rain followed by showers for all. It too though shows pressure rising over Europe which may steer some of the heavy rain away from the South and more towards the NW as we enter 2014.
NAVGEM closes it's run with a powerful storm system centred between Scotland and Iceland next weekend with strong to gale WSW winds and rain followed by squally showers affecting all parts next weekend with wintry showers again over the hills.
ECM shows the post Christmas storm much further South this morning and less deep crossing the Centre of the UK. Nevertheless it would provide Southern regions with a potent gale and spell of heavy rain while the North sees colder and more showery weather before all areas remain changeable thereafter with the New Year period looking every bit as unsettled as a new deepening Low rattles into the UK from the Atlantic on New Years Eve.
The GFS Ensembles remain an unsettled bunch maintaining total Atlantic domination throughout on sometimes strong Westerly winds. As a result little if any sign of significantly cold or indeed mild weather shown with plenty of rainfall over the period from most members.
The Jet Stream shows the flow across the Atlantic and on collision force with the Uk throughout the next week. It troughs South of the UK over Christmas briefly before the next storm system pulls it North again post Christmas. In the neverland it does show signs still of wanting to ridge North around an Atlantic High but it looks like it could be flattened quite quickly again as pressure is put on it by further cyclonicity exiting the States.
In Summary there is absolutely no sign of any change in the weather pattern over the next 10 days with further gales and heavy rain at times for all. Hopefully any damaging weather looks restricted to Monday and Christmas Eve now with a quieter but still unsettled period over Christmas itself especially across the South. there is the chance of a white christmas for a few as cold uppers could bring some of the colder air to the surface in heavy showers, most likely in the West and North. As we exit Christmas and into the New Year there is little difference with yet another storm system up to the North dictating the wet pattern for the period. The only nugget of hope for drier weather could come from a rise of pressure to the SW, South or SE as we move into the New Year shunting the deepest part of depressions further NW and restricting the severity of wind and rain to these areas. However, I appreciate this is not what cold weather fans want to here as if it verified it would keep cold weather well away from the UK well out into January at least.
Martin G
Kilmersdon Radstock Bath Somerset