Hi everyone. Here is my latest rundown of the midnight outputs from GFS, UKMO, GEM, NAVGEM and ECM for today Thursday August 1st 2013.
The General Situation. A warm front lies over Scotland with a warm and humid SSE flow over England and Wales. Overnight tonight a weakening cold front moves East over the UK at the same time as a thundery trough moves NE grazing SE England tonight. Tomorrow will then show Low pressure to the NW of the British Isles with a showery SW flow over the UK which lasts for much of the weekend with a slack pressure gradient developing over the UK along with upper air disturbances floating about in the flow. In weather terms England and Wales will be very warm today and hot in the SE. A band of scattered and showery rain moves East tonight with a low risk of thunder in the far SE tonight before all of the UK settles into a bright and fresher spell of weather with sunshine and scattered heavy and thundery showers in temperatures returning closer to average for early August.
GFS then shows a new Low pressure ambling across Southern Britain on Monday and out into the North sea midweek with the threat of more prolonged rain for a time before a return to showers looks likely. A ridge of High pressure develops from the SW over Scotland to begin with and then topples down over the South next weekend with a drier and warmer phase before troughs move into the North from the West with some rain at times. Later in the outer reaches of the run a deep Low develops over Scandinavia with a cool and blustery NW wind over the UK for a time with sunshine and showers for the middle of the month with the best weather in the SE close to Higher pressure to the South.
The GFS Ensembles indicate a lot more mobility to the Jet Stream and resultant Low pressure areas later in the month as a succession of troughs and ridges cross the UK over the second half of the period in very average temperatures and sometimes breezy Westerly winds. Before we get there the current warmer interlude evaporates into a slack and showery period with light winds and occasional showers.
The Jet Stream as indicated above becomes a dominant force in the outcome of conditions in the next few weeks as it first moves in a NE flow across the UK in the next 4-5 days before it tilts more West to East over the UK and strengthens markedly in Week 2 steering depressions in from the west close to Northern Britain.
UKMO today shows a very slack Low pressure area over the UK in the middle of next week with a mix of sunshine and slow moving heavy showers and thunderstorms in temperatures close to average. the showers would be most prolific in the daytime's with some reasonably cool and fresh nights.
GEM this morning shows a showery and changeable start to next week too with some heavy showers around at times. It slides further downhill later in the run as it pulls in a bulls eye Low from the West across Southern Britain at the end of next week with wet, windy and eventually showery weather for all in rather cool conditions should it evolve.
NAVGEM shows a less dramatic period next week with the showery period the other models show also in evidence up until midweek. Though things don't really settle down on this run thereafter there is some signs of the Azores high edging closer to Southern Britain later next week.
ECM is a much prettier sight longer term this morning as although it shows a basically changeable pattern next week with rain or showers at times for most the Azores High ridges in nicely to end the run which would displace the changeable weather with warm and sunny conditions for next weekend and beyond.
In Summary there is a lot of unsettled looking output on the table this morning with nearly all models without exception indicating at best a showery theme next week and at worst some wet, windy and cool weather on occasion. However, it's not all doom and gloom and despite the fact that only a few models pick up on it in this run the Azores High looks to be strengthening later next week along with the Jet Stream across the Atlantic. This could have a detrimental effect on our weather as some models show in their windy and wet evolution's late next week but it could work in our favour too as it could push the Jet further north again and allow High pressure to ridge back NE across the UK as ECM suggests and to a lesser degree NAVGEM isn't a million miles away. This may be a trend we see more of over the coming days so although on the face of it the output for fine and warm weather fans is somewhat poor it may look better in a few days time.
Martin G
Kilmersdon Radstock Bath Somerset