Sunday, 12 April 2015

Weather guide Monday 13th to Sunday 19th April 2015

Headline: Mostly dry with sunny spells; very warm mid week with thundery shower risk

March 2015 summary

March continued the trend of very average weather thus far in 2015, both temperatures and rainfall close to the norm, some areas were quite dry though and most places were sunny. Once again a month that lacked extremes, nothing colder than -5c or higher than 13c here at Llanwnnen, a limited range. Some rainfall totals:

Capel Curig, Snowdonia c. 192mm
Trawsgoed, Ceredigion c. 95mm
Llanwnnen, Ceredigion 72.6mm 87%
Aberporth, Ceredigion 54mm
Pembrey Sands, Carms 58.0mm
Llanelli, Carms 77.2mm
Milford Haven, Pembs 69.4mm
Long Lawford, Rugby 28.5mm 67%
Church Lawford, Rugby c. 34mm
Bablake School, Coventry 46.2mm 97%
Coleshill, Warks 52.4mm
Hereford 45.6mm
Little Rissington, Cotswolds c.32mm

Last fortnight's highlights

A windy, unsettled end to March with gales and heavy showers, wind gusts of over 40mph almost everwhere, highest being 97mph at  the exposed location of Capel Curig. April came in cool and turned somewhat damp, much of West Wales (WW) below 10c max on Wed 1st. The rest of the turn of month week saw rather cool to average temperatures at best, frost though largely absent. Rain at times the Thursday night and for Good Friday, especially wet over Pembrokeshire where some places had close on an inch.

A big improvement occurred over the Easter weekend to warmer, sunnier conditions and with a mostly fine and warm week just gone. This improvement first took effect over WW during the weekend, but all areas joined in by Easter Monday with plenty of warm sunshine, although some coastal areas were plagued by sea mist and fog. There were slight overnight frosts in places throughout last week - especially inland WW where Llanwnnen had a least a ground frost each night to Friday. Some mornings were foggy before the sun broke through, as was the case across Warwickshire both Monday and Tuesday mornings. Temperature-wise overall it has been a warm week for early April (at least by day) considering the average maxmum should be around 12c at this stage:

Monday saw temperatures reach 19.4c at Pershore (highest in UK), 19.0c Pembrey, with many places above 16c, however parts of Cardigan Bay much cooler with sea mist, Gogerddan, near Aberystwyth managing just 11.2c with Aberporth only marginally milder. On Tuesday several places topped 18c including 18.4c Llanwnnen and an unbroken 12 hours sunshine, with Wednesday and Thursday warm and mostly sunny again, 19.6c reached on both days at Llanwnnen - warmer than any official UK station, Porthmadog reached 18.7c Wednesday, while Trawsgoed hit 19c Thursday. Friday, the last day of the warm spell, saw temperatures widely above 18c, best of all being Pershore, Worc at 20.7c and Trawsgoed 20.3c; much cooler along the south Wales coast however due to a fresh onshore wind, max just 12.4c Milford Haven, Pembs. Some rain Friday night into Saturday but then a cooler and fresher day but largely dry with temperatures only a little below the mid April average.

The week ahead

Plenty more dry and at times warm weather once more this week - hopefully this good April will not dash hopes of a fine, warm Summer, as is often the case when the nice weather arrives too early! Not so good on Sunday though, an Irish low bringing strong to gale force wind for Wales with some rain or drizzle at times this afternoon, heaviest for Snowdonia, highs 11 or 12c. Windy for the Midlands Sunday afternoon and clouding over with a little rain possible later afternoon into the evening, maxima 13 to 15c here. Winds become light this evening and a dry night with clear spells and widespread ground frost and local air frost, -1c in places. High pressure close to southern England on Monday although weak fronts bringing quite a lot of cloud even some drizzle in places. However the sun should break through from time to time especially inland, but parts of the WW coast affected by low cloud and mist from off the Irish Sea. Highs Monday rather mild at 13 to 16c, although cooler for some western coasts. Mostly dry Monday night with no frost concerns.

A warm rather humid SSW flow across England and Wales on Tuesday, sunny spells and decent temperatures of 18 to 20c, although some coasts plagued by sea mist keeping it chilly, and a breezy day over much of WW.  A dry night follows. The warm air still in place for Wednesday although pressure will be falling off as a cold front edges across northern Britain. Sunny spells, light winds with temperatures likely to exceed the magic 21c (70f) in places! Highs in the 19 to 22c range, perhaps the odd 23c being recorded over the Midlands. Cooler in general though for Cardigan Bay and coastal NW Wales with again some sea fog lapping beaches. The warmth inland may set off some sharp showers afternoon with even an isolated thunderstorm or two knocking about by evening and rumbling into the night, especially further south. 

Thursday sees a weak front lying somewhere across southern Britain with a new (cooler) high building over northern parts and killing it off further. Areas of cloud, and perhaps a few vestigial showers, in association with the front should be breaking up to give sunny spells afternoon, a cooler day, highs closer to average at 13 to 15c but pleasant enough out of the breeze and shade. There is a ground frost risk for Thursday night but Friday another fine, dry day with sunny spells and temperatures at least up to average and possibly quite a warm feeling day.

Next weekend too looks like having high pressure in charge, quite pleasant and largely dry with sunny spells for most of us, WW perhaps most favoured for warmth as a NE breeze may keep it cooler at times into the East Midlands, but overall expect maxima in the 13 to 17c range. A continued risk of ground frost through the weekend as the ambient air may be quite cool.

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