Good evening. Here is tonight's report on the midday outputs from NWP for today Wednesday December 18th 2013.
All models show an active cold front attached to a very deep depression to the NW of Britain crossing quickly East over the UK this evening. Following behind will be a colder and still windy period of weather with a mix of clear or sunny intervals and heavy and frequent showers of rain, hail, sleet and snow the latter most likely but not exclusively over the hills. Then after a bright start to Friday a new area of heavy rain will sweep NE across the UK with renewed severe gales in the NW. Showery air will return to the North of the UK later with a slower clearance for Southern areas as a new wave runs along the cold front giving rise to another very wet spell for the South on Saturday. Sunday will then be a colder day for all with sunshine and showers, wintry on hills.
GFS then shows the whole of the Christmas Week as wet, windy and occasionally stormy with severe gale or even storm force winds at times giving rise to flooding and wind damage issues almost anywhere over the period. After Christmas improvements are slow with plenty more fast changing conditions alternating between wet and windy weather to sunshine and showers, wintry at times. Overall things would turn somewhat colder, especially in the interludes between the rain areas.
UKMO shows Christmas Eve as a rather cold and windy day with gale or severe gales across the North and West in particular with frequent showers giving hail, thunder, sleet and snow in places.
GEM shows very unsettled with very deep Low pressure encircling the UK with some very potent small centres delivering very heavy rain and strong winds for all at times. It will become more generally less mild with some snow at times over the hills.
NAVGEM tonight shows a very wet Christmas too with low pressure spiraling across the Atlantic and the UK with heavy rain and severe gales with sleet or snow showers at times over the hills.
ECM tonight shows plenty of wind and rain over the Christmas week with severe gales at times and plenty of rain with wintry showers over the hills at times, especially across the North.
The GFS Ensembles show a sine wave pattern indicative of a very mobile and Atlantic based weather pattern. There will be plenty of rain with local flooding issues if some of the charts verify and some colder interludes too when some sleet or snow showers could fall over the hills.
The Jet Stream shows the flow continuing more or less unabated across the Atlantic and across the British Isles for the reliable future.
In Summary there seems no real letup now in the very unsettled and potentially stormy spell of weather which will take us through the Christmas period and up to the New Year. Although never technically very cold at any point the volatile nature of the weather will result in some unexpected weather events to show up, be it snowfall or thunder, lightning hail and even mini tornadoes. Wind damage will be feasible at times ad most importantly with continual heavy rain events occurring there will be an increasing risk of flooding as rainfall totals rack up quickly over the next week or so.
Martin G
Kilmersdon Radstock Bath Somerset