Good evening. Here is the report on the 12 noon outputs from GFS, UKMO, GEM, NAVGEM and ECM for today Sunday November 17th 2013.
All models show a change to colder conditions soon. The change comes in two tiers, the first being a rather unsettled tier with a band of rain crossing SE tonight and tomorrow and introducing a rather cold and showery NW flow for 24 hours or so with wintry showers over the hills and most frequent in the North and West. Then a depression crossing SE down the North Sea on Wednesday brings a spell of wind and rain for all with sleet or snow on the highest ground before a change to colder and more showery weather returns on Thursday, leading us into the second tier. This phase then shows strong rises in pressure with an Anticyclone shown to be firmly over the UK next weekend with attendant still, cold and frosty conditions with the potential for dense and freezing fog patches reluctant to clear by day.
GFS then shows it's entire remainder of the run with the UK bathed in High pressure either over or nearby to the NW. As a result little change from this cold and settled theme with frost and fog coming and going day to day seems likely with very little rainfall for anyone.
UKMO closes it's run with High pressure firmly across the UK with fine and settled conditions with the twin winter perils of frost and fog in abundance for most of the UK.
GEM tonight shows a more temporary phase of High pressure next weekend before it drifts away to the NE before collapsing altogether late in it's run at the expense of deep Atlantic Low pressure with wind and rain moving slowly in from the SW and West. Temperatures would be held somewhat below average until the milder air associated with the wind and rain arrives later.
NAVGEM keeps High pressure close to the NW with a cold NNE drift across the UK for most of the time. This would be insufficiently strong to prevent frost and fog problems developing night and morning in an otherwise dry and sunny spell of weather.
ECM shows High pressure over the weekend and being reinforced from the NW later with cold conditions sustained across all areas with copious amounts of frost and freezing fog too if the light NE feed stays slack enough. By Day 10 High pressure lies close to NW Britain with a chilly and dry theme for most with a cold wind from the NNE with some sunshine by day but still with the risk of frost and freezing fog overnight.
The GFS Ensembles show a cold period to come, particularly across the South before conditions are shown to average the long term mean from the mid point of the run. More unsettled weather is also shown to develop from many members in the second half of the run with rain at times as the Atlantic gathers momentum later. The operational was a cold outlier especially across the South.
The Jet Stream flow is unavailable tonight.
In Summary the weather looks like becoming and staying rather cold for a week or so at least. There are strong signs from GFS and possibly GEM later that an Atlantic breakdown will end the colder theme while ECM is more dogmatic with a new surge of cold sinking over Europe and then SW over Britain following several days of cold and frosty conditions. Which is right will need more runs to solve but there is plenty of scope shown from reliable model sources that cold weather will never be far away over the coming few weeks.
Transcript taken from:-http://www.norton-ra...is(2859336).htm
Martin G
Kilmersdon Radstock Bath Somerset