Good morning. Here is the report on the midnight outputs for the UK from the outputs of GFS, UKMO, GEM, NAVGEM and ECM for today Sunday September 8th 2013.
The General Situation. The UK lies in a slack Westerly flow with Low pressure over Northwest Britain. Through today and tomorrow this transfers East and weakens as a trough swings East over England and Wales with showers, heavy and thundery in places. Through the early days of the week the weather will become largely dry in the West bt with a few more showers in the East as Low pressure lurks over the low Countries for a time. It will be quite cool especially by night and under the showers. Ny midweek a ridge covers the UK before a weak cold front crosses SE later with some occasional light rain for a time before the end of the week looks like the weather will become dry again with the ridge from the SW re-establishing itself again, especially across the South.
The Fax Charts show a complex and showery Low pressure area simplifying over the next 24 hours or so as the whole system pushes bodily South and East to take most of the showers away with it. Things are shown to take longer to dry up in the extreme east before a ridge topples over the UK midweek and in turn followed by a series of weak fronts over the latter half of the working week turning things more cloudy with some drizzly rain for a time in cloudy and quite chilly feeling West to NW winds.
GFS then shows a spell of rather cloudy West to NW winds over the UK lasting several days with the North most at risk of occasional rain as weak troughs pass by. the South would maintain a lot of cloud with only limited brightness but little if any rain in temperatures close to average. This pattern persists for a time before High pressure to the South slides East and leads to a more definitive trough to move West to East over the UK later with some showery rain for all before High pressure builds back close to the West once more to end the run with any remaining showers limited to the extreme East under a cool Northerly breeze while elsewhere becomes dry and fine but cool especially at night.
The GFS Ensembles show a good consensus of agreement over the next 5 days or so before the spread between members becomes quite large. The general message though is that the greatest risk of rain is reserved for the north with the South seeing very little and just occasionally. The operational was a warm outlier in the South yet again with temperatures overall trending close to average for mid September.
The Jet Stream shows the flow troughed down over the UK at present which weakens steadily over the coming days as the Jet flow re-establishes itself flowing West to East over or to the North of Scotland in response to the Azores High ridging NE to Britain.
UKMO today shows the Azores High elongated towards the UK early next weekend with a mostly dry week ahead interrupted by a brief cold front giving a little rain over the UK for a time before fine and dry conditions look like returning again in time for next weekend.
GEM today shows a West to NW flow too with a cold front clearing SE early next weekend. Thereafter the North would see the main share of further rain from further injections of Atlantic low pressure which does extend further South at times but on the whole the South and SW would continue to see the best chance of staying largely dry and at times bright.
NAVGEM finally joins the suite too finally giving up the idea of the Low hanging around to the South this week in preference of a cold front moving SE at the start of the weekend then setting up a fresh NW flow with a lot of cloud but only a little rain this chiefly in the North.
ECM is quite similar but does show a more vigorous Westerly flow developing later next weekend as a deep Low moves East to the North. So after a benign weak with just a little rain on a cold front towards the weekend the weather will turn windier and wetter in the North for a time before fine weather returns yet again behind another weakening cold front moving SE giving just a little rain to the South ahead of another ridge from the Azores High.
In Summary it looks like another period when the Azores High is going to continue to rule the roost as regards the weather over the UK with any attempts to bring more unsettled weather down from the NW rather weak and reserved mostly for the North. With winds from the West or NW for much of the time and given it is now September temperatures are unlikely to be much if any above average but with no cold air to tap into conditions would be workable for many though cloud amounts look likely to be large at times. So after today's and tomorrows potential sharp showers things turn benign for the foreseeable future with little interesting synoptics to talk about currently.
Martin G
Kilmersdon Radstock Bath Somerset