Sunday, 29 November 2015

Weather guide Monday 30th November to Sunday 6th December 2015

Last weeks review: dull and unsettled with occasional rain or showers; cold start then often mild.

Mostly dry with sunny intervals last Sunday, quite cold in many places but  some coastal parts of WW did attain average (Pembrey 9.7c, Shobdon 8.2c, Nottingham max 4.7c). Quite a sharp frost followed with temperatures widely below -2c with the -6.1c here at Llanwnnen colder than any official weather place in the UK (Tirabad, Powys -4.5c, Pershore -3.8c). Brightness for a time Monday but it clouded over with rain over NW Wales afternoon reaching other places during the evening. Cold over the Midlands (sub 7c max) but milder eventually for WW by evening (Valley 10.9c, Shawbury 6.8c). Temperatures continued to rise during Monday night reaching 12c over SW Wales with further rain for a time.

Tuesday was mostly cloudy with showery rain in places, this mostly affecting Mid & North Wales (Capel Curig 32.2mm) and also the NE half of the Midlands beyond Stafford & Leicester, with Pembrokeshire and the central & SW Midlands mostly dry, temperatures close to or a little above average (daytime highs Pembrey 10.5c, Hereford 10.4c). Quite mild and windy Tuesday night across Wales with further showers, heavy in places, drier and less breezy with clear breaks over the Midlands even permitting a ground frost at Pershore (air min 2.8c cf Pembrey 9.4c). Showery rain affected Mid and North Wales and the West Midlands Wednesday, the latter via a 'Cheshire Gap' streamer that squeezed showers between the hills of North Wales and the Pennines steering them in line SE across the Midlands, some places getting one after the other (Shawbury 9.2mm 24 hrs to 06z Thursday = wettest in UK). Quite mild in most places on Wednesday (Hereford 12.8c, Pembrey 12.3c) but another rather cloudy day.

Mild and mostly cloudy Thursday with a little rain or drizzle in places (Milford Haven 13.2c, Shobdon 12.8c), temperatures over parts of the Midlands suppressed to around average though (Church Lawford 9.5c). Mild and cloudy again Friday with an active cold front spreading rain and strong winds east during the afternoon and evening, heavy rain in places (Capel Curig 33mm). The front also brought a marked cool down as winds veered NW with a drop 3 or 4c in one hour (max before this Pershore College 12.8c, Pembrey 12.3c). Enough clear spells and wind drop to permit a widespread ground frost over the Midlands Friday night, most of WW too breezy for this though (air min Shobdon 0.3c, Llanwnnen 0.9c). Saturday started dry in places but unsettled again with showers and some longer spells of rain accompanied by strong winds. A cooler but far from cold day (Pembrey 11.6c, Pershore 10.4c, Nottingham max 7.2c).

The week ahead: unsettled and mostly mild, wet and windy at times; drier Friday into weekend

A very mild Saturday night, no lower than 10c along the south coast of Wales (min Milford Haven 10.7c). Windy on Sunday with severe gales for exposed places as winds gust above 70mph, courtesy of recently named storm Clodagh crossing northern UK.  A lot of cloud this afternoon with scattered rain or showers, heavy in places, very mild highs 11 to 13c, though perhaps a few late sunny intervals. Any remaining showers clearing this evening as it cools down to give a local ground frost in a few spots. However the next system brings cloud and rain after midnight and a wet windy dawn to Monday. Fronts then set to loiter all day across central Britain, so cloudy with spells of rain, Wales being particularly wet with many places ending up with a good inch while Capel Curig could get as much as 3 inches (75mm) taking its November total to around 800mm (31 inches)! Strong to gale force SW winds accompanying the wet weather as well during much of Monday but at least it will be academically very mild  at 12 to 14c.

Further spells of rain on Monday night again especially over Mid and North Wales as the fronts start to ease northwards drying it out over South Wales and the Midlands by dawn with just some residual drizzle. A very mild night temperatures in places remaining above an exceptional 12c and still quite windy. Tuesday sees a mild sweep of SW winds, mostly cloudy with occasional light rain or drizzle, a few bright intervals possible over the Midlands, very mild again highs 12 to 14c and rather windy. Another very mild night follows with further light rain or drizzle in places, no lower than 9c anywhere.  A cold front then edges SE during Wednesday bringing spells of rain and squally winds but it should reach 11 to 13c ahead of the front.

Fronts then look like stalling and even waving back over us during Wednesday night into Thursday which means further spells of wet weather to come (no doubt with flooding in places by this stage). It should be mild in most places still for a time Thursday (up to 13c over South Wales and the Midlands) but on the northern edge of the fronts much cooler air digs in, so perhaps only around 7c by afternoon for Snowdonia even with the risk of hill snow for a time before it clears. The clearance and colder air should then reach all places later on Thursday with some residual evening showers over WW and a much colder night with frost in places.

Model variations quite large come Friday, some having high pressure and dry conditions which could last into the weekend, others though keeping it unsettled although not as wet and windy as it will have been in the preceding days with pressure almost certainly somewhat raised by that stage and hence any fronts are weaker. Looking ahead to the middle of December and no sign of either prolonged cold or dry weather as the generally unsettled mild theme continues.

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