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Weather guide Monday 19th August to Bank Holiday Monday 26th August 2013



[font=Helvetica][b]Headline: Plenty of dry and warm weather, perhaps breaking down over the holiday weekend?[/b][/font]

[font=Helvetica][b]The week gone:[/b][/font]

[font=Helvetica]A cooler feel early last week, temperatures only reached 17.5c on Monday at Llanwnnen (the coolest day for 6 weeks), and 17.8c at Coventry on Tuesday, we did though get warm, but moist air Thursday into Friday, 25c being reached at Coleshill and Wellesbourne in Warwickshire on Thursday with some pleasant sunny spells too. Not much rain until Thursday, the very moist, warm air enveloping the UK then produced copious rainfall through Thursday night, which was not anticipated to this level in last week's guide! Trawsgoed, Ceredigion, was the wettest spot in the UK in the 24 hours to 6am Friday receiving 58.6mm rainfall, and many parts of Wales had betwen 25 and 50mm (one to two inches) rain during Thursday and Friday. All this rain caused localised flooding in Mid and North Wales on Friday and even a landslide onto the A487 near Corris, South Gwynedd. Nor did the Midlands escape the deluge, with Coventry having 26mm in the 24 hours to 0900 Friday, however much of the Midlands had less at 10 to 15mm. [/font]

[font=Helvetica][b]The week to come:[/b][/font]

[font=Helvetica]A much better prospect in the coming week with plenty of dry and warm, even very warm weather, however this may not last over the Bank Holiday weekend. Saturday's damp weather has moved off leaving a mainly dry and bright Sunday with just a few scattered showers in places. Highs on Sunday afternoon between 19 and 21c with a moderate westerly breeze. Clearing skies and reducing breezes tonight means a cooler night than of late (incidentally last Wednesday was the warmest night of this Summer here, a low of just 16.5c), temperatures down to 8 to 10c away from coasts. A ridge of high pressure builds in from the SW through Monday, a dry and bright day, some decent sunny spells, only the isolated light shower possible over Welsh hills, and a refreshing westerly breeze, highs of 18 or 19c for West Wales and 21c for the Midlands. Clear periods and quite a cool night again follows, minima ranging from 13c on coasts to 8c for some inland rural spots. High pressure over southern England on Tuesday, warm and sunny for the Midlands, sunny spells too for West Wales, although perhaps clouding over later in the afternoon here. Highs on Tuesday a pleasant 20 or 21c for West Wales and 24c for the Midlands.[/font]

[font=Helvetica]A weakening disturbance tracks close to NW UK on Wednesday, so perhaps more in the way of cloud and even a shower or two in places, and a very slight chance of isolated thunder, but many places remaining dry. Rather warm and humid on Wednesday, maxima generally between 21 and 25c, highest over the Midlands, where warm sunny breaks are more likely afternoon. Clear spells overnight with lows 11 to 14c. High pressure centred to our NE over Scandinavia on Thursday with a warm to very warm SE to east flow advecting our way off the Continent. Models varying in just how warm this air will be, but the potential for temperatures to reach 27c 80f in places on Thursday, and with plenty of strong sunshine and gentle breezes. A clear night to follow so at least temperatures drop to a comfortable 11 to 14c. [/font]

[font=Helvetica]Diverging model outputs from Friday - as should be expected with a Bank Holiday weekend imminent! A lot of uncertainty then with the holiday weekend, and some may be disappinted after all the media hype for a prolonged late August heatwave, conversely it may still turn out warm and reasonably dry! High pressure may well though not be in ascendance by next weekend, although we may avoid a washout weekend at least. Friday first, and another very warm day is likely, but there are suggstiions of a thundery breakdown later in the day and into Saturday. Sunny spells should be expected on Friday with maxima of 23 to 27c widely, and then by evening some showers or thunderstorms could be affecting some areas.[/font]

[font=Helvetica]The all important weekend, and the latest GFS model brings a low right over Wales and England, producing showers and longer spells of rain along with a marked cool down. That's the bad news..the good news is that this particular model run is a marked 'outlier' with little support from the rest of the 'model suite'! Here, we shall 'go' with the ECM model along with much previous recent GFS output which has shown reasonable consistency in having high pressure over northern UK, and so painting a somewhat drier even pleasant picture. [/font]

[font=Helvetica]Next weekend then is expected to see plenty of dry and warm weather with sunny intervals at least, but also the risk of some rain or showers at times. Greatest risk the further south you are of some thundery rain or showers, and more especially on Saturday it is felt, as ECM has a thundery low over northern France for Saturday. West Wales looks most favoured for some warm and fairly sunny conditions at times over the Bank Holiday weekend due to the anticipated NE flow which will serve to break the cloud crossing the hills to our east. [/font]

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A mainly dry week gone but breaking down earlier on Friday than anticipated, uncertainties were stressed however from this point!

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