Sunday, 15 February 2015

Weather guide Monday 16th to Sunday 22nd February 2015

Headline: Often dry and bright - turning unsettled from Thursday with rain and wind at times; quite mild

Last weeks highlights

Last weeks high pressure saw highly contrasting conditions within short distances and from day to day: firstly last Sunday when while many places were rather mild and sunny for a few it stayed cold and foggy, temperatures reached 11c in Herefordshire (after a low of -5c) but just 3.4c at Shawbury in neighbouring Shropshire. Contrasts stark on Monday too with some areas sunny and quite mild (as was Swansea max 11c)  with others cloudy and chilly (as Llanwnnen max 4.7c). By Tuesday a marked temperature inversion was occurring under the high pressure so that unusually the monutain tops of Scotland were warmer than the lowlands of Wales and the Midlands. At 1245 metres up on Cairngorm temperatures reached 9c Tuesday afternoon compared with 3 to 5c for most of Wales and the Midlands, 2c the 'high' at Tirabad, Powys being the coldest spot in the UK. Snowdonia existed as islands above a sea of cloud on Tuesday thanks to the inversion:

Wednesday and Thursday were chilly, dry and mostly cloudy days, the near normal temperatures envisaged in last weekends blog suppressed by the cold low level air trapped within the high, however all the cloud meant most places were frost free midweek. Milder with rain for most Friday the first significant rain of February, although Snowdonia and much of the Midlands saw just small amounts. Temperatures widely reached between 8 and 10c, a rare mild one for this month to date. Only 3.2mm rain at Church Lawford (Warks) at the half way point of February, the driest spot in our regions.

The coming week

Another reasonably dry week ahead so it does look like February will end up a drier than average month. Temperatures although not especially cold have struggled this month but will be making a recovery towards the average this week as we see milder conditions predominating. Turning more unsettled from Thursday with rain fronts and strong winds at times.

It has been a cloudy, misty Sunday morning over the Midlands, while a sunny, frosty start here in Ceredigion. A dry day bar the odd spit out of the Midlands mist. Further sunny spells for West Wales (WW) this afternoon but probably rather cloudy for the Midlands, highs close to average at 7 to 9c with light winds. Clear intervals may permit a ground frost this evening for the Midlands but WW clouds over as a band of rain moves in from the west, so turning wet here around midnight. This rain reaching most of the Midlands by dawn Monday by which time WW has dried out again. The rain front slows down over the Midlands and may not clear the east of the region until late afternoon, but for WW and the West Midlands a bright afternoon with a few scattered showers on Monday. Maxima 7 or 8c.

A strong ridge of high pressure moves in from the west during Monday night so any showers soon die out leaving clear periods and a slight frost as winds drop light, minima 0 to -3c. Tuesday a largely dry day, sunny spells especially for the Midlands and temperatures again near average at 7 to 9c, quite a pleasant afternoon with only light breezes. Quite an intense high is situated just to our south by Tuesday night which will be dry with clear spells and a slight frost, although perhaps too much cloud and breeze for this across WW. Lows Tuesday night just below 0c Midlands nearer 5c coastal WW.

Weak fronts may mean a rather cloudy day threatening some drizzle for WW during Wednesday but the Midlands remains under influence of the high and has a dry day with sunny intervals. Mild on Wednesday max 9 to 11c but with a freshening SW wind especially across Wales. Perhaps enough clear breaks and light enough winds for a grass frost over parts of the Midlands Wednesday night but frost-free with drizzle in places WW. Thursday may turn more unsettled as a front moves in from the Atlantic but perhaps another dry day for the Midlands. For WW though some spells of rain at some stage during Thursday although perhaps not vast quantities and quite a fresh SW to west breeze, Highs Thursday 7 to 10c so pretty mild.

The trend seems to be for much more mobile unsettled westerlies by the end of the week as the jet stream cranks up fuelled by the extreme cold over North America. Unsettled then for Friday and the weekend, all areas seeing rain and strong winds at times although still with dry, bright interludes so no washout weekend in prospect. Back into the weather we saw during January really, that of fluctuating temperatures and sharp spells of rain and wind, as warm sectors swap with marked cold fronts seems the pattern as we move towards the end of February...

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