Good morning everyone. Here is the report on the midnight outputs of GFS, UKMO, GEM, NAVGEM and ECM for today Thursday August 15th 2013.
All models show a moist and warm SW flow over the UK with extensive cloud, hill fog and occasional rain. A cold front is shown to move SE across the UK tonight and tomorrow with a spell of quite heavy rain for all. Then a clearer and fresher WNW flow moves in behind the rain tomorrow before winds back SW and freshen on Saturday as a deep Low to the NW sends troughs across the UK from the West with spells of rain then showers for all Saturday into Sunday. Then the weather gradually improves from the SW early next week although the speed of improvements differs this morning between the outputs.
GFS then shows Tuesday as the day when High pressure gets a grip on things as it moves up from the SW to cover Southern areas at first then more general areas by soon after midweek with increasingly warm and sunny weather developing. Then next weekend High pressure splits with one cell moving off east while a new one positions close to the North with an Easterly flow developing over the South in the second week. This just about holds firm until the end of the run with dry, bright and warm weather for most with Low pressure over Southern Europe just close enough at times to promote the odd thundery shower at times in the far South.
The GFS Ensembles today show the operational all over the place today being bot a cold and warm outlier from quite early in in the run in the South. The general theme from the pack though is that there will be a strong warm up next week which could move into Week 2 as well as High pressure builds from the SW eradicating the risk of rain for many areas away from the far NW as well as presenting the UK with some fine, warm and sunny weather.
The Jet Stream today still shows the flow moving across the Alantic and over the UK until early next week when it shifts further North towards Iceland and the Denmark Straits as High pressure pushes it away North as it transits into the UK.
UKMO this morning is somewhat disappointing as it shows the synoptic situation for next Wednesday with High pressure still just off to the South with much of the UK still under the influence of a Westerly feed of air with variable cloud and the chance of rain in the North still quite High. Southern areas should see some good dry and bright weather with temperatures slowly on the rise.
GEM does show a better push of High pressure into the UK before it loses it's grip to a new centre just up to the NW which settles winds into the NE and East in the South. Some fine, warm and sunny weather would develop across the South and east early next week before all areas join in later. There is an increasing risk shown of thundery showers reaching the South as Low pressure over France edges perilously close to the South at times.
NAVGEM today is a great looking run for sun worshippers as it moves the High across the UK next week to form an elongated form lying East to west across the UK with fine, very warm and sunny weather likely for virtually all of the UK.
ECM does show a few headaches this morning as it pulls the high up into the UK early next week. The spoiler in the Atlantic continues to be a pest for the model to handle throwing a spanner in the works for the North and West on this run next Wednesday with cloud and some rain. However, once filled and moved away High pressure does push across the UK and on into Scandinavia with fine and warm weather developing for all before a trough moves slowly NE across the UK next weekend with a spell of thundery rain possible for a time.
In Summary today the prospects still look good for a change to warm and settled conditions from early next week after a spell of wet and windy conditions this weekend. There are a few cracks to fill in along the way this morning mostly caused by a small Low which rides over the top of the growing anticyclone around midweek hindering improvements for the North at least. However, all models show high pressure eventually winning overall control with several days of very warm and sunny weather likely for all later next week before as always some models hint at a possible threat from rogue Atlantic troughs or something more thundery popping up from the South in the far reaches of the outputs.
Martin G
Kilmersdon Radstock Bath Somerset