Good evening. Here is the report on the midday outputs from GFS, UKMO, GEM, NAVGEM and ECM for today Wednesday November 13th 2013.
All models show a cold front crossing England and Wales this evening and tonight, clearing the SE by morning. A band of rain will clear to showers and rather cold air. Through tomorrow pressure builds and a ridge develops across the UK on Thursday night and Friday with the risk of a frost tomorrow night. On Friday milder Atlantic air will creep around the Northern flank of High pressure to the SW with most of Friday and Saturday ending up benign and rather cloudy with moderate Westerly winds and little if any rain or sunshine and average temperatures. On Sunday the weather remains rather cloudy and a band of rain will slip South across the UK through the day.
GFS then shows the start of next week with a cold northerly flow setting in with wintry showers flooding down from the North for a time. Temperatures will fall below average and as a ridge of High pressure pushes in from the West frosts at night will become more notable and sharp. However, milder air will again filter around the Northern flank of High pressure down to the SW with cloudy skies and a moderate West wind alternating with further incursions of colder and potentially wintry showery air at times, at least over the North.
UKMO shows a deepening and cold Northerly flow moving down from the North on Tuesday with wintry showers in the North extending to all areas with snow to lower levels in the North and even the chance of seeing some over Southern hills too above 1000ft or so.
GEM shows a cold Northerly developing early next week with wintry showers over Northern, Eastern and Western coasts with a lot of dry weather inland with some frosty nights. Little change then is shown in this overall pattern out to Day 10 with frosty nights and daytime temperatures remaining on the low side of average for all with the continued risk of wintry showers in the East.
NAVGEM also shows a cool off next week but with less power to any Northerly feed. Instead Low pressure down to the SW and up to the NE allows a weak ridge to be maintained over the UK from mid Atlantic with cold and frosty weather likely with some freezing fog patches possible too.
ECM tonight shows a cold Northerly plunge at the beginning of the week with some rain followed by wintry showers with snow over the hills. As the run lngthens High pressure to the NW moves in closer to the NW with frosty cold conditions here. In the South Low pressure over Europe maintains a chilly Easterly or NE flow with rain or sleet in places.
The GFS Ensembles show a sharp fall in uppers after the next three or four days. This though is steadily eroded away to more average uppers when taken as the pack. High pressure is the dominant factor and the catalyst to feed milder Atlantic winds across the UK between colder polar air phases with some rain on the boundary fronts at times.
The Jet Stream shows the flow riding high ver the Atlantic and over Iceland currently. Later in the weekend and next week it dives South from the Iceland area and down over or to the West of the UK. Beyond that there is some suggestion that a more Southerly tracking Jet could maintain rather colder conditions near the British Isles.
In Summary tonight the theme of colder weather is strengthening as each day passes. GFS only goes for a short cold shot before milder air infiltrates around a High to the SW and over the British Isles. All other models go for something rather more sustained with a cold northerly spell giving way to the possibility of a more NE feed across the South as High pressure builds to the NW cutting any Atlantic attack off. In reality I still feel that several days of cold and unsettled weather when some may see some snow will eventually be transferred into a High pressure based pattern, it centred somewhere near the UK giving widespread frost and fog problems and largely dry weather.
Martin G
Kilmersdon Radstock Bath Somerset