You may have noticed it's been rather wet and windy recently and the disturbed weather will continue right up to Christmas Day (and beyond). We have a deep area of low pressure sat to the NW of Britain today, which is bringing rather unsettled and windy conditions to many areas. A slow-moving frontal wave across SE England, which has brought persistent rain for much of the day, is now clearing - but of more concern is a rather active trough briniging squally convective rainfall with embedded thunderstorms and now arriving across west Wales and NW England - this is producing wind gusts of 50-60mph across west Wales, torrential rainfall and there may also be some hail and a small risk of a tornado in it too. For further info on this, a storm forecast has been issued:
http://www.netweather.tv/index.cgi?action=convective;sess=Sunday brings a brief respite from the wild weather, but it's all downhill on Monday morning, as another rapidly deepening area of low pressure moves in from the Atlantic towards the NW of Britain by Tuesday. Winds will pick up as a very potent cold front sweeps east ahead of this low Monday afternoon, and GFS is indicating widespread gales or severe gales with passage of this front:
Then as the deep low approaches the NW of Britain, the very strong gusts in the wind field close to this low will affect Nern Britain, with gusts widely reaching 60-70mph from Tuesday afternoon across Scotland, N Ireland and N England, perhaps 70-80mph for a time, isolated gusts of up to 90mph offshore/exposed western coasts. Gales will be possible further south too and the notable thing about this low is how long it stays close to the NW of Britain, which means a prolonged period of gales or severe gales across many areas Monday through Xmas Eve and into Xmas Day.
As well as being very windy Xmas Eve, it's going to turn colder. A pool of cold polar maritime air surges east then northeast across the UK beneath the deep low NW of Britain on Tuesday, its origin over the Northern Territories of Canada. This cold rPm flow follows the active cold front surging east Monday Pm, which itself will bring a spell of widespread gales or severe gales.
Forecast dew points falling below 0c increasingly widely on Xmas Eve, and forecast 850-1000mb thicknesses falling sufficiently for wintry showers arriving across the west in the strong southwest flow to fall as snow across northern and western areas - though settling maybe reserved for higher gound initially. Severe Gales across the north close to the deep low to the NW would likely bring blizzard conditions in any snow showers.
Xmas Day itself looking to be a cold day, with temps in low to mid single figures in the rPm southwesterly flow, cold enough still for some wintriness in the showers likely across the west - though the cold air arriving Xmas Eve looks to be mixed out by then, but for most areas away from the far west it's looking dry, sunny, cold but rather windy at first, though the southwesterly wind easing through the day.
Further ahead, not a great deal of change showing until the end of the year at least, with a very mobile and disturbed Atlantic - bringing a risk of deepening secondary lows across the UK bringing more wind and rain, with alternating mild and cold maritime airmasses - which will allow some marginal snow to fall in places - more especially in the north. As Ba said, prominent arctic high showing later in the GFS and ECM runs, which may expand towards Barents and Greenland to help perhaps break-up the vortex as we head into the New Year - but a long shot for now.
