Sunday, 15 March 2015

Weather guide Monday 16th to Sunday 22nd March 2015

Headline: Mostly dry with sunny intervals and just the odd shower; some frost but temperatures around average 

Last weeks highlights

Frosty last Sunday night, -3c or -4c in places, and the coldest night of the week with further slight frosts through to midweek and again this weekend more locally.  Some rain on most days last week, with parts of the Midlands tending to escape mostly dry. Tuesday though was fine, sunny and rather mild max 10 to 12c, although Cardigan Bay coasts cooler with onshore breezes, Aberporth reaching just 7.9c. Heavier rain over West Wales on Thursday particularly for Pembrokeshire, Anglesey and the Llŷn Peninsular where the rain band stalled for much of the day, highest official total being 26mm at RAF Mona, although a Personal Weather Station (PWS) near Caernarfon reported above 50mm (2 inches) for the day.

Thursday was the mildest day of the week for the Midlands where it stayed dry until late in the day, highest reading 13.7c Pershore with most places getting above 12c. Thursday night into Friday it was the turn of the West Midlands for the heavy rain - the 24 hours to 0900 Friday having 16.2mm at Bablake, Coventry making it their wettest March day since 2008, while the east Birmingham area had over 20mm. The rain band only reached as far as Northampton though during Thursday night before deciding to nudge back west as it fizzled out on Friday! There was a little snow over some Welsh hills as colder air dug in from the east beneath the decaying front. This weekend is turning out mainly cloudy and cool, Tirabad in Powys reached just 4.0c Saturday.

The week ahead

With high pressure always close by a reasonably dry week can be expected, bar the odd light shower (especially during Monday and again by the end of the week perhaps). Temperatures never straying far from the mid March average (9 to 11c) although any sunnier days are likely to be milder, and any clearances overnight will readily see a slight frost forming.

Sunday and the ENE winds are bringing a lot of cloud again from off the North Sea, so quite cool and although largely dry, there will be some drizzle or light showers in places, particularly the Midlands. West Wales (WW) may brighten from time to time but for many quite a dull, cheerless afternoon  max 7 to 9c. With all the cloud tonight frost is unlikely, although any clear intervals would readily produce temporary grass frost locally. The large Scandinavian high is still there into the start of the coming week, so another chilly day Monday with east to SE winds, plenty of cloud, a few sunny intervals and a scattering of mostly light showers, these mainly over the North Midlands above Coventry. Maxima Monday rather cool again at 7 to 9c. Cloud still stubborn on Monday night, although clear breaks are more likely over Wales where there will be a widespread ground frost at least, down to -1c in places.

A rather slack SE flow for Tuesday, a better chance of some sunny intervals, just an isolated light shower in places, but most parts remain dry, highs milder at 10 to 13c with a light SE breeze, so feeling pleasant enough in any sunshine Some clear spells during Tuesday night give a more widespread ground frost although this may come and go as cloud amounts vary, generally no lower than 1c.

The Scandinavian high has moved away by Wednesday only to be replaced by a new high centred near Northern Ireland. A dry day with sunny intervals, a cool NE breeze although highs of 10 to 13c are not so bad. Clear spells and a widespread frost for Wednesday night, down to -2c locally especially WW. A similarly dry, bright day for Thursday, extensive cloud at times but decent sunny spells for some areas and maxima 10 to 13c, but still that nagging cool NE breeze.

Model differences by the end of the week revolve around the positioning of the high, GFS keeps it close by while ECM has been consistent with the idea of pulling it further west which would allow a colder northerly flow across the country later Friday into next weekend. In any event Friday should be another largely dry and bright day, perhaps turning colder later in the day with a few showers into the North Midlands? Saturday too, overall, is looking mostly dry with sunny intervals although perhaps chilly, and IF the colder scenario comes off wintry showers will be a possibilty.  Sunday could be the start of a more unsettled end to March. Still the risk of frost in places by night next weekend.

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