Good evening. Here is the report from the 12 noon outputs from GFS, UKMO, GEM, NAVGEM and ECM for tonight Thursday November 28th 2013.
All models illustrate a spell of anticyclonic gloom coming to an end briefly as a cold front crosses SE across the British Isles tomorrow bringing cleaner and fresher air to all areas by tomorrow evening. Winds will strengthen markedly from the NW and could carry a few showers to NE Britain for a time before Saturday sees decreasing winds with quite a pleasant day for many before cloudier weather spills down from the NW to land us back to square one on Sunday with largely cloudy and non-descript weather to start next week with temperatures remaining close to the seasonal average as High pressure maintains a ridge across Britain from the West. Frost and fog would be relatively limited in amount through this spell with Friday and Saturday night's the only nights at substantial risk.
GFS then shows a weak series of fronts cross SE soon after midweek with a little rain ahead of a colder phase, especially across NE areas while elsewhere stays dry and probably quite bright and only a little colder. By the weekend wet and windy weather spreads first across Northern Britain and then on to all areas as a deep Low crosses East to the North of Scotland and down over NW Europe. The cold front would bring a short spell of cold NW winds and potentially wintry showers of sleet and snow in the North before a ridge of High pressure brings a change to increasingly milder weather with any rainfall becoming more and more confined to Northern areas as Southern Britain sees some potentially very mild weather for a time.
UKMO today shows High pressure well under control of the weather still over the UK with a strong ridge across Britain from a centre over mid Atlantic. The quiet and benign weather of early in the week looks like persisting with perhaps a few more brighter interludes by day and clearer interludes at night to promote a little more in the way of frost and fog.
GEM shows a front moving South midweek with some occasional rain for a time before clearer conditions move down from the North and then another band of more coherent rain spreads down behind on a more active front and this time is followed by a spell of cold NW winds with wintry showers and night frosts to end the run.
NAVGEM too shows a couple of fronts moving SE through the middle of next week, the second of which brings a spell of cold and showery weather with sleet or snow showers over all high ground and frost at night.
ECM tonight shows a brief spell of rain midweek behind which a cold NW flow brings some wintry showers to the North and East before High pressure slides over from the West keeping things cold but bringing dry weather with frost and fog. By Day 10 it looks like Northern areas will see milder air moving in off the Atlantic while Southern areas stay flat calm under High pressure.
The GFS Ensembles show a short colder interlude towards the back end of next week before the general trend is for thing to return to average by the end of the period. The current High pressure and precipitation less weather that we are currently experiencing will most likely continue for the next week or so before it is shown to give way to somewhat more unsettled conditions from many members later. Tonight's mild ending shown by the operational was a big mild outlier at the end of the run.
The Jet Stream tonight shows the flow remains to the North of the UK before it is directed SE over the UK later next week. thereafter, the flow becomes indeterminate and hard to find a pattern from with many options possible.
In Summary tonight there is still a week of High pressure based weather to wade through with benign and cloudy conditions with just a brief window of colder and fresher weather for 36-48hrs from Friday. Later next week still looks like turning cold across the UK with the threat of some sleet or snow in parts of the North especially but most output still indicate the North flow providing the cold being shunted East quite quickly and replaced by High pressure with frost and fog possibilities late in the period. It should also be noted that there still is a good chance that some milder weather will return over the UK late in the period as High pressure may become flattened to the South.
Martin G
Kilmersdon Radstock Bath Somerset