Good morning all. Here is the report on the midnight outputs of the big five, GFS, UKMO, GEM, NAVGEM and ECM for today Wednesday August 7th 2013.
The General Situation. All models show a slack area of pressure across the UK currently with a mix of sunshine and well scattered showers. This theme continues until Friday when a front crosses from the West with some rain for all for a time. A return to WNW winds and scattered showers in the North is likely on Friday while the South stays largely dry. On Sunday a further band of rain crosses East over the UK before cooler and more showery NW winds affect all areas on Monday and Tuesday.
GFS then maintains something of a North/South split throughout the rest of it's run today with sunny spells most plentiful for Southern regions where it stays dry for longer spells than further North where rain or showers are far more likely close to successive Low pressure areas passing East to the North. Temperatures will be close to average for the most part though it could feel rather cool at times in the rains in the North and rather warm in the South in the more prolonged brighter spells.
The GFS Ensembles show a pattern where High pressure is never far away to the South or SW with a North/South split in the weather prevalent. There will be long periods of fine and bright weather across most Southern areas but it would never become very warm with temperatures close to average for the most part in a Westerly breeze. The North is shown to be far more likely to receive rain as Low pressure is indicated just to the North at times in average temperatures. A cool anticyclone is indicated to cover the UK right at the end of the run with fine weather more likely for all by then.
The Jet Stream is shown to blow across the Atlantic towards the UK in an undulating form for a time before it moves directly West to East across the UK for a time next week. there are signs of it wanting to return further North later as it weakens and breaks up.
UKMO today shows a NW flow to start next week with sunny spells and scattered showers the likely weather. The North and Northeast will see the most showers by Tuesday as a ridge of High pressure approaches the West. Temperatures would be close to average in a moderate and cool feeling breeze.
GEM today shows a much stronger NW then Westerly flow over the UK which after a showery start becomes more and more unstable for all with rain and showers. It would feel cool in the breeze particularly later as winds veer towards the North with some chilly nights expected then.
NAVGEM keeps winds from a Westerly point across the UK but maintains High pressure close to the South with fine and dry weather for the most part here while the North remains more prone to slightly more unsettled weather at times with occasional rain or showers.
ECM finally is very similar to the rest with a cool NW flow at the start of the week but it then sides with GEM in gradually introducing a Westerly flow with much more potency delivering rain or showers from troughs moving East over all areas later in the week with temperatures no better than average and a blustery wind.
In Summary the spell of benign conditions this week last into next week too before a couple of models namely GEM and ECM spice things up a bit later next week with a more sustained and stronger Westerly flow with rain at times from Atlantic fronts. Not all models or members within model runs support this outcome though with some suggesting that High pressure remains close enough to Southern Britain to steer the worst of the rain bearing fronts over more Northern areas. The one constant between the output is that it is unlikely that we will return to a spell of the fine and very warm weather we saw in July. However, the South will feel very pleasant at times in what will be days of broken cloud and a Westerly wind with temperatures at comfortable levels overall and just a little rain at times. The North might be slightly less fortunate with more noticeable rainfall here at times but this would be nothing unusual for these areas and even here some drier interludes are likely.
Martin G
Kilmersdon Radstock Bath Somerset