Sunday, 10 May 2015

Weather guide Monday 11th to Sunday 17th May 2015

Headline: Often dry and bright bar the odd shower; Thursday though cool with rain and showers and perhaps windy

Last week's highlights

A disappointing start to May, often cool and showery, with some longer spells of wet weather, although parts of the Midlands did have some decent dry, brighter spells and temperatures closer to normal (which for that region in early May is around 16c). It has also been a dull and wet start to May, parts of North Wales have already reached the average rainfall due in a whole month of May! Last Sunday alone 15.8mm fell on the city of Coventry, more than during the preceding 4 weeks, while at Nottingham 19mm was almost as much as the total for whole of April (20.2mm). Quite warm after the rain cleared last Sunday over the Midlands up to 19c although there were some heavy downpours and even a few thunderstorms scattered about. In contrast it was a cool day along parts of the Welsh coast (Aberdaron max 11.7c, Pembrey 12.2c) and Snowdonia (Capel Curig 11.4c) though with plenty of cloud and fresh winds.

Monday was dry with temperatures around average but rain arrived during the evening with quite a wet night, various places getting around half an inch. Unusually windy for May on Tuesday, a 60mph squall at Coventry Airport, a 52mph gust recorded on the roof here at Llanwnnen, and with almost 70mph for some more exposed parts of Wales such as Capel Curig (67mph) and Mumbles (69mph). Tuesday to Thursday were all essentially cool and showery days, but there were some longer spells of wet weather on Tuesday for Wales, only a few places missing out.  Maxima quite poor for May on Tuesday with all the cloud and showers nowhere higher than 14c, worst of all max 9.2c at Capel Curig which was also the wettest spot in the UK with 35mm. Still some showers about on Election Day although more places tended to miss them, not Trawsgoed however which was one of the wettest spots in the UK catching 8.6mm. Cool again Thursday, although parts of the Midlands saw more reasonable temperatures of 15 or 16c.

 Tuesday 5th May 2015 wind gusts:

A few places had a grass frost Thursday night, then Friday saw more general rain in most areas, NW Wales particularly wet again getting around 25mm (one inch). Capel Curig ending up with 35.6mm in the 24 hours to 0700 Saturday and was the wettest spot in the UK for the second time in a week, hardly any rain though for the South Midlands on Friday. Saturday saw an improvement to generally dry, brighter and, at least for some, milder conditions too, here at Llanwnnen at 14.4c it was almost 3c warmer than Friday.

The week ahead

On Sunday and Monday we are between low pressure west of Ireland and high pressure over the Continent to our east and south. A deep moist, mild SSW flow on Sunday means a rather windy and mostly cloudy day with the odd spit of drizzle for WW, with the sun perhaps poking through at times afternoon. Better chances of some sunny spells for the Midlands with less wind here too so feeling quite warm this afternoon. Highs Sunday 16 to 18c WW and 20c for parts of the Midlands. Generally dry overnight and mild no lower than 9c or 10c. Rain arriving across WW before dawn. Patchy rain across WW during Monday morning, this front tending to fizzle as it edges east into the Midlands but still giving some showery rain in places there afternoon. Sunny intervals too during Monday and quite warm for the Midlands with some places again touching 20c, nearer 15 to 17c WW with a fresh SW wind. Monday night largely dry and fairly mild.

High pressure building close to our SW on Tuesday but perhaps not enough to prevent a scattering of showers, and a fresher feeling day with a moderate to fresh WNW breeze. Some pleasant sunny intervals too Tuesday with temperatures close to average at 14 to 17c, and any showers dying out come evening leading to a clear, calming and cold night with quite a widespread ground frost, down close to 0c locally. High pressure crossing the UK Wednesday should just about give a dry, fine day with sunny spells and highs between 16 and 19c. Fronts from the SW though perhaps introducing cloud and showery rain in places come evening.

Low pressure in some form or other will be crossing the UK during Thursday which will be a cooler and very unsettled day. Probably we will be seeing early rain, heavy in places that should turn to showers afternoon, a chance of thunder in these showers. A cool day with all the cloud, rain or showers no better than 13 or 14c. Potential for strong to gale force winds Thursday as well, this dependent on actual form and postioning of the low come the day. Some showers or longer spells of rain may linger well into Thursday night.

For Friday and next weekend high pressure will be attempting to influence our weather from the SW but with low pressure still close to northern Britain at times. Plenty of reasonably dry and bright weather then seems likely come next weekend, although often with a cool NW to west breeze so never feeling especially warm. We could be affected by the odd passing weak front producing a spell of light rain or shower but the weather should be predominantly dry. Expect maximum temperatures Friday and through the weekend to be in the 13 to 17c range with a ground frost risk should skies clear and winds drop enough by night.

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