Good morning everyone. Here is my take on the midnight outputs of the NWP (Numerical Westher Prediction) from the midnight outputs today Tuesday December 17th 2013.
All models show a period of potentially stormy weather with the exception of today where the weather is rather quieter as a brief ridge of high pressure crosses from the West. Later tonight and from tomorrow everywhere the winds will become strong for all from the SW and very strong for some with severe gale or even storm force gusts for a time in the NW later tomorrow as a vicious Low is shown to sweep NE across NW Scotland. Rain, very heavy for a time will sweep East followed by a 36-48 window of colder weather with strong West winds and showers, wintry on all hills even in the South and giving accumulations over Northern elevations. Then on Friday and the weekend the weather becomes milder again with spells of rain and gale force SW winds though the colder and showery variety of weather could spill back across at least Northern areas for a time again over the weekend.
The GFS operational run shows the run up to Christmas simply put as wet and windy with strong to gale SW winds and mild weather particularly in the South. Over Christmas itself the weather turns colder and there will be plenty of showers around for all areas, especially in the West driven in by gale force winds with snow on all high ground of the North and maybe in the South too at times. The very volatile pattern of rain followed by showers continues then up to and including the New Year with rain and strong winds alternating with colder and brighter spells with showers, wintry in the North.
UKMO shows next Monday as a windy and wet affair as another wave disturbance runs quickly East in the near gale WSW flow bringing further heavy rain across Southern areas through the day followed by righter colder and more showery weather in the north and West later.
GEM shows unsettled weather throughout next week, becoming deeply unsettled by Christmas with very low pressure values over the UK, strong Westerly winds and heavy rain and showers at times, increasingly falling as sleet and wet snow at times over high ground, especially over the Christmas period itself and in the North.
NAVGEM also shows a wet and relatively mild start to next week before things become more alternating over Christmas itself between wet and windy weather to rather colder and showery conditions with strong winds continuing unabated throughout.
ECM today shows a wet and windy run up to christmas followed by a rather chilly and very windy Christmas with squally showers of rain and hail with sleet and snow over the hills.
The GFS Ensembles continue to show no let up in the powerful Westerly flow across the Atlantic aided by a Jet Stream rushing East across the British Isles from the Atlantic. Hence periods of wet and windy weather is indicated from all members with an overall trend of maintaining average temperatures but very wet conditions at times for all.
The Jet Stream is shown to continue in it's powerful state crossing the Atlantic and over the UK in the period up until Christmas. Beyond that it sinks somewhat South at times bringing much of the UK on the cold side of the flow with the increased threat of wintriness in the showers for the UK later in the period.
In Summary the weather looks like remaining and becoming even more deeply unsettled throughout the forecast period this morning. All models show the potential of quite a wild Christmas with cold Westerly winds and wintry showers from which some places could indeed see a white Christmas though wide scale snowfall is not expected with the higher ground favoured for any settling snow albeit briefly. At other times severe gales could occur giving their own brand of travel disruption and when coupled with the likelihood of heavy rain with attendant flooding issues there looks to be plenty to talk about over the UK in the next few weeks weatherwise to distract observers from the family festive activities.
Martin G
Kilmersdon Radstock Bath Somerset