UK Monthly Weather forecast.

[Derek Cummings - South Wales.]

The UK weather for this month - issued by East Midlands forecaster Terry Scholey.

[Derek Cummings - South Wales.]

 May 2012 - latest update.

General Comments:

Although much wetter than expected, the April forecast brought a couple of notable successes, with the month turning out to be colder than March as predicted. When you consider this has only occurred four times since 1659 interestingly all of them in the last 55 years, we hope this proved useful.

The other success was in the overall circulation pattern through April, which apart from a brief spell during the third week proved to be accurate. The current ‘blocked’ pattern is now being carried over into May, with winds mostly between North and East probably until around the 20th.

These winds when of Arctic origin can bring late crop and blossom damaging frosts, with Scotland, Northern Ireland and the North of England most at risk during the first half of May. Here though it should on the whole be drier and somewhat brighter than elsewhere until around the 20th, with the best of the sunshine over West Scotland giving occasionally pleasant afternoons but cold nights.

Remaining parts of the country will not be immune to some cold nights either during drier, clearer intervals although here, occasional bouts of more humid air may try to invade from the South or South East. This could give a few brief warmer, sunnier intervals in the South but as we have already seen during April, the two opposing air masses can produce copious amounts of rain most likely in central and southern areas, where thunderstorms are also expected.

After around the 20th a more varied circulation pattern seems likely, with a southerly component in the wind more likely. This highlights the chance of a fine spell of summer weather or a possible heat wave mentioned last month during the final week of May or June. In quite a few of the relevant past years studied however the fine weather came during the third week, but current events do not suggest this.

Despite warmer weather later in the month, mean average temperatures will probably below normal in the North and East and closer to normal in the West and South. Relative to normal, it should be drier than average in the North and West and wetter than normal in the East and South. Sunshine amounts should be closer to average in the North West, but below normal in the East and South.  Confidence in this May forecast particularly the first half is high.

Period Summaries

May 1st to 5th: High pressure to the north should bring mainly dry weather to Scotland and Northern Ireland, with the best of the sunshine in the West. Chilly nights however could give ground frost. Elsewhere and more especially in central and southern areas it will be unsettled at times and more cloudy. Occasional outbreaks of rain could be heavy giving local thunder, with just brief drier warmer intervals mostly at first. Later it should become drier in a chilly wind especially in the East, with a risk of ground frost at night in the North. Maximum temperatures in the North should be 10 to 14C, with minimum values 1 to 4C. Some southern parts may reach 18 to 20C briefly at first, but it will turn colder here also, with temperature values similar to those of more northern areas later.

May 6th to 11th: A North West/South split, with the North and West of Scotland and perhaps Northern Ireland generally having the driest, brightest weather. Variable cloud will allow sunny spells especially over West Scotland, but there will be a few showers that could be wintry on hills. There will also be a chilly wind, with a continued risk of overnight slight or ground frost. England and Wales will see the odd drier, brighter day, but with a ‘nagging’ chilly wind at times. Whenever somewhat warmer air attacks from the South, southern and some central in particular will turn wet, with sporadic bursts of rain and some thunderstorms. It may also be misty at times in the East, where temperatures may occasionally struggle to get above 9 to 11C. Generally though, maximum temperatures should be in the range 12 to 16C, but occasionally perhaps up to 19C in the South, with minimum values between say 3 and 8C.

May 12th to 16th: Should see conditions becoming drier and brighter more generally but with variable cloud. The North and East may see a few lighter showers for a while, but a finer, warmer interval looks possible around mid-month with light winds and extended sunny spells. On the chilly side at first with still the risk of ground frost in the North and possibly in some central parts. Daytime temperatures should eventually reach 14 to 18C, with minimum values probably between say 3 and 8C.

May 17th to 20th: Probably just a subtle change, with breezier conditions giving a few showers in the East and South. A few could be heavy locally, in probably rather cloudy conditions with a chilly wind. Elsewhere it should be drier and brighter in lighter breezes, with variable amounts of cloud giving sunny spells especially in the West. Here temperatures should reach 15 to 17C but where skies stay clear at night it could still turn quite cold. Minimum values should be mostly in the range 3 to 7C, with still the risk of ground frost in some sheltered Scottish glens. It may still be quite chilly towards the East coast for a while, with top temperatures in the East and South say 12 to 16C, but the nights although probably feeling chilly should be somewhat milder, as minimum values probably fall to between 6 and 9C.

May 21st to 25th: The pressure systems should re-arrange themselves, with winds probably turning into the South or South West. It may briefly be finer, but the weather could turn somewhat unsettled with showers particularly in the North and West where it may also become quite breezy. The South and East could also see scattered showers between intervals of warm sunshine. It should certainly feel more like late spring, with maximum temperatures of 13 to 17C in the North and West and 18 to 21C in the East and South. The nights should also be milder, with minimum temperatures mostly in the range 8 to 13C.

May 26th to 31st: Central and eastern areas should see some very warm, summery weather at times, but a few heavy showers or thunderstorms are possible. Further West showers seem more likely with cloudy skies at times, but here too it could be quite warm and there should be sunny intervals. Top temperatures about 14 to 19C in the West and 20 to 25C in the East. The nights will be mild and perhaps slightly humid, with minimum temperatures between say 9 and 1

1st May 2012 T.G.S.