Hi everyone. Here is this morning's account of the midnight outputs from GFS, UKMO, GEM, NAVGEM and ECM for today Friday November 29th 2013.
All models maintain High pressure close to the West of Britain over the next three or four days. It's centre has pulled a little further West today which has allowed a colder and fresher NW flow down across the UK today behind a weak cold front, For most this will mean largely dry conditions still but brighter and cleaner air later will improve the complexion of the day. This weather type with a few showers, wintry on hills in the NW will last through until later tomorrow when the High moves back towards the UK and brings a return to cloudy skies down from the NW with benign and non-descript weather for the following few days, taking us towards the middle of next week when some change begin to take place.
GFS then splits High pressure East and west of the UK but with very little difference felt at the surface as winds remain very light and slack over the UK away from a stiffer westerly breeze in the far North. Then at the end of next week, probably on Friday a cold front introduces cold and clearer air down to all areas with some wintry showers over he North and East for a time before High pressure returns across the UK with sharp frosts and fog patches. The second half of the operational today sinks High pressure down to the SE but close enough by to maintain largely fine conditions. Temperatures would steadily rise through the period with some very mild weather possible across Southern Britain later if a low level inversion can be avoided.
UKMO today shows High pressure over the Eastern Atlantic next Thursday orientated West to East with a strong ridge across Southern Britain maintaining the theme of cloudy and largely dry weather with average temperatures for England and Wales while Scotland and Northern Ireland see a stronger Westerly wind and occasional rain later.
GEM this morning shows High pressure close to or over Southern Britain towards the end of next week relaxing South briefly to allow a change in weather type to dry and cold weather with clearer skies later in the run with frost and fog at night becoming much more of an issue as High pressure builds back across all areas to end the run.
NAVGEM shows High pressure close to the SW late next week with rather cloudy and dry conditions giving way to a spell of wet and windy weather in the North as a small Low zips East across Scotland. The South would probably see a little rain from this as it's cold front cleared SE.
ECM shows a ridge across Southern Britain next Thursday with winds freshening markedly from the West with rain over the North. The High is then pulled West as a strong Northerly flow pushes down through Friday to all areas with very cold conditions with snow showers giving accumulations in Northern and Eastern areas for a time. Then through next weekend the cold air relaxes as winds back NW then West bringing less cold and more cloudy air across the UK from off the Atlantic with temperatures slowly returning to average.
The GFS Ensembles show a rather cold set overall this morning with the operational I described above very much one of the warmest members of the pack later on. It looks like most members support a rather cold period between the 5th -11th and with some precipitation around sleet and snow is a possibility for a time, especially across the North and East while the South look likely to avoid this. As usual a wide range options are shown late in the run with the most likely scenario being a return to average early December values with rainfall amounts looking still quite suppressed through the period, especially in the South.
The Jet Stream this morning is programmed to maintain it's path to the North of the UK for the next 5-6 days before it turns SE or South across the UK in association with the colder phase late next week. It then returns slightly further north to a positions between Scotland and Iceland thereafter on a NE course indicating a bias towards High pressure close to SE England.
In Summary this morning the models are all over the place with conditions in the interesting part of the output from the middle of next week. In the shorter term the quiet and benign pattern remains with few features in the weather offering any interest with much cloud cover, light winds and temperatures close to average with little in the way of frost and fog away from tonight and possibly tomorrow night in the South. The fun and games begin later next week with some output showing a potent plunge of cold air from the North leading to some snowfall for some, more especially in the North and East. Some output make little of this pushing the thrust of this too far East while most others weaken it quite quickly as High pressure builds back in from the West with a spell of cold and clear weather with sharp frosts seeming likely before the inevitable infill of cloud returns with slowly less cold conditions and a return to what we have now possible. It remains interesting over the next few runs how this phase of potentially very cold weather is developed or dissolved to nothing more than a blip. Time alone will tell.
Martin G
Kilmersdon Radstock Bath Somerset