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graphs      CLIMATE-UK.COM'S  REVIEW  OF  THE  BRITISH  METEOROLOGICAL  SCENE
     MONTHLY  SUMMARY
     No. 617       For     MAY      2007
          VERY WET AND DULL IN THE EAST AND SOUTH;  VARIABLE TEMPERATURES
Text Box: Although April’s high pressure persisted until the 5th, a cyclonic type prevailed for much of the rest of the month apart from a brief anticyclonic spell between the 21st and 24th. Mean monthly sea-level pressure was below normal over all parts of the British Isles (and practically the whole of Europe too), with anomalies ranging from -3mbar in Cornwall to -7mbar in Shetland. The anomalous flow over the UK was WNW-ly. With an anticyclone located just north of Scotland, east to northeasterly winds affected Britain until the 5th, maintaining the dry and settled weather which had characterised April. The best of the sunshine and highest temperatures were found in southern and western districts while eastern and central areas were cool and cloudy at times. Hurn (Dorset), reached 24°C on both the 1st and 2nd, while Tulloch Bridge had a diurnal range of 24.4 degC (-2.1°C to 22.3°C) on the 2nd. Valley (Anglesey) logged 66h of bright sunshine during the first five days of the month, and at Tiree (Inner Hebrides) the sun shone for 118h between 26th April and 5th May. A very disturbed cyclonic/westerly type took over from the 6th until the 20th, with troughs and depressions crossing the country at frequent intervals, the depression of the 13th/14th being particularly active. Rain spread across all parts of the UK during the 5th/6th, and in parts of east Kent this was the first measurable rain since 30th March. The 6th was windy in northern Britain, with gusts approaching 60kn in the Western and Northern Isles, and showers fell widely over the next few days, locally accompanied by hail and thunder. Daytime temperatures were well up to normal, but there were local night frosts in Scotland. Rain fell widely on the 9th, 10th, and 11th as a sequence of three depressions crossed the country, and the 13th was exceptionally wet across England and Wales as another depression crossed the country; 25-50mm fell over a wide area of Southwest England, Wales, the Midlands and Yorkshire, and Preston Montford (Salop) collected 79mm. Scotland enjoyed a fine interlude with long sunny spells, but there were locally sharp frosts at night and Kinbrace (Sutherland) recorded -4.2°C early on the 14th. It was briefly warmer on the 17th-18th especially in the Southeast where highs of 22-23°C were observed, but Text Box: it became windy especially in Scotland where gusts of 55-60mph were widely reported on the 18th. Pressure now built across the UK and the weather became quieter for a few days with warm sunshine in most districts except western and northern Scotland; the temp-erature reached 23-25°C in the Home Counties on the 23rd, 24th and 25th, peaking at 25.7°C at Heathrow airport on the 24th. A cold front brought sharply cooler weather from the northwest later on the 25th and 26th, accompanied by showers and local thunderstorms, and early on the 27th the temperature dropped to -5.7°C at Kinbrace (Sutherland). A deep depression moved into the Southwest Approaches late on the 26th, whence it tracked eastwards across Cornwall and into northeast France. Rain spread northwards as far as southern Scotland, and it was heavy and prolonged south of a line from Pembrokeshire to the Humber. Some 50-75mm fell in a broad zone stretching from Dorset and Hampshire to Norfolk. At Luton (Beds), where extensive flooding led to the cancellation of the International Carnival, 99mm fell in 48 hours from 21z on the 26th. In the wake of the depression strong northerly winds uprooted trees and triggered power outages on the 28th, and in the Southeast this was one of the coldest late-May days on record with a high of just 6.4°C at Whipsnade (Beds). The cool and unsettled regime persisted until the month’s end with thundery showers over England and Wales, and heavy rain over the east and north of Scotland (53mm at Loch Glascarnoch in Wester Ross on the 30th). Mean temperature ranged from 1.0-1.5 degC above normal in southern England to 0.0-0.5 degC below in northern Scotland. Districts bordering the Irish Sea had slightly below average rainfall, but most other areas had a wet May, and new records were established at several long-term stations in southern England where over three times the normal monthly rainfall was reported locally. Sunshine aggregates ranged from 40 per cent above normal at Fair Isle, between Shetland and Orkney, to 40 per cent below in the East Midlands and East Anglia where it was locally the dullest May since 1991.