Sunday, 25 October 2015

Weather guide Monday 26th October to Sunday 1st November 2015

Last weeks review: Mixed, some rain, temperatures around average

High pressure kept it mostly dry at first last week, Sunday was mostly cloudy, just a few light showers affecting the Midlands, temperatures close to average (Llanwnnen 14.3c, Pershore 13.6c, Capel Curig max 11.1c). All the cloud meant a mild Sunday night, staying above 11c in places (Mumbles min 11.6c). Rather cloudy and generally dry then last Monday, average to quite mild (Mumbles 16.9c, Sutton Bonington 15.0c). Another dry frost free night followed. Dry and bright Tuesday, again temperatures average to mild (Pershore 16.0c, Milford Haven 15.9c).

Appreciable rain for all for the first time in about a fortnight during Tuesday night, here at Llanwnnen a run of 12 successive completely dry days ended - the longest dry spell of 2015! Some very heavy rain in places (and contrary to the expectations for merely light rain in this guide) - 35.8mm at Gogerddan near Aberystwyth in the 24 hours to 2100 Wednesday (wettest in the UK), 11mm of this fell in the hour to 0600, many places even over the Midlands received around half an inch (e.g. Coventry 14.0mm). Wednesday and we were in mild humid westerlies with most of the rain or drizzle dying out (Hereford 18.4c, Aberdaron 15.7c).

Very mild Wednesday night, some places not below 12c (Valley min 12.6c). Somewhat cooler air arrived Thursday which was dry with sunny intervals and temps still fairly mild (Newport, Salop 16.1c, Mumbles 15.3c). Clear spells allowed a touch of ground frost for parts of the Midlands overnight. Rather cloudy and cooler with drizzle in places Friday (Valley 14.1c, Pershore College 12.8c). Some rain at times on Saturday which started mild, with early morning maxima across WW, but turned cooler but at least Wales and eventually the West Midlands dried out afternoon (Pembrey 13.8c, Pershore College 13.9c). 15.8mm rain fell at Gogerddan on Saturday compared with just 1mm at Shobdon (Herefordshire) which illustrates the 'rain shadow' effect that the Welsh hills often exert.

The coming week: Unsettled with rain at times, often mild; drier brighter intervals, especially Midlands

Quite an unsettled week to come but with timing and positioning of fronts and thus rainfall difficult to ascertain and so this guide is liable to come unstuck! Frosty Saturday night in many places but this may well be the last frost for a week or so as mild winds from between SE and SW are set to prevail. A ridge is giving a dry fine Sunday with plentiful hazy sunshine this afternoon, highs around average for the end of October at 11 to 13c. A SSE breeze picks up this evening which should prevent any frost tonight and it clouds over by morning at least across Wales. A slow moving and rather deep low to the west or SW of Ireland controls our weather through the early part of this coming week:

During Monday the fronts are for the most part over Ireland and so for most places it will be a dry day with some sunny intervals, although Pembrokeshire will be mostly cloudy with the threat of some rain from time to time being closest to the fronts. The low to our west dragging up mild air from the south, maxima between 13 and 15c, perhaps the odd 16c, a moderate to fresh SE breeze though. The rain fronts may edge a little east on Monday night which could be wet for parts of WW as a consequence, remaining dry over the Midlands, a mild night minima 8 to 11c.

Slow moving fronts strung out over Wales much of Tuesday which could well be a wet day for those parts that it gets stuck over the longest! At present the GFS model has Pembrokeshire experiencing the wettest conditions on Tuesday but this is liable to change being 48 hours away still. Some rain for all eventually though on Tuesday, even for the Midlands, although it may hold off until late in the day for Leicester and Nottingham when the front should make a more NE push. Very mild for the Midlands with the SE flow and given a few sunny intervals it could reach 17 or 18c in places here, more like 13 or 14c for wetter parts of Wales.

The rain should clear most places during Tuesday night, but much uncertainty exists over the behaviour of these rain fronts, and in any case there may be a few sharp showers over Wales in their wake. Wednesday looks like we are between the main frontal zones so a drier picture, sunny intervals but with showers in places, some of which may be heavy, temperatures reaching 12 to 14c with lighter winds. Thursday may well see further rain fronts crossing the UK bringing at least a spell of rain and fresh winds, although either side of this it should be reasonably dry, and parts of the Midlands may see little if any rain with the fronts liable to weaken as they progress east. Highs ostensibly rather mild at 12 to 14c Thursday but it may turn out quite a windy cool feeling day.

Friday and much of next weekend continues in an unsettled vein as further lows or fronts cross the UK bringing showers or longer spells of rain and potentially strong winds through from time to time, there should also be some dry bright intervals as well. There is some potential showing for a more definite prolonged wet period Friday into Saturday although some other models show fronts getting through faster with rain spells more brief. Additionally some of the models hint at an improvement by Sunday as a ridge dries things out. Temperatures Friday and over the weekend look average to mild with frost unlikely.

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