back
graphs      CLIMATE-UK.COM'S  REVIEW  OF  THE  BRITISH  METEOROLOGICAL  SCENE
     MONTHLY  SUMMARY
     No. 616            For    APRIL    2007
WARMEST APRIL SINCE AT LEAST 1659, DRIEST SINCE 1984 AND SUNNIEST SINCE 1893
Text Box: On the 16th highest pressure transferred to the west of Ireland allowing cooler air to travel around its eastern flank, but this new anticyclone moved back across the UK on the 19th and 20th, reaching Germany on the 21st. A moist south to south-westerly airflow affected the country for the next four days. A drop in temperature over northern Britain on the 16th affected all except southernmost counties over the next few days, and in Shetland there were snow showers with a high at Lerwick of 3.5°C on the 19th; overnight frosts were widespread; Kinbrace (Sutherland) recorded -3.9°C early on the 20th. The next few days were much warmer (23.5°C at Gravesend, Kent, on the 22nd), and overnight temperatures were remarkably high for the season on 23rd/24th and 24th/25th with a minimum at St James’s Park (London) on the latter night of 14.5°C, but it became generally cloudy with outbreaks of rain. The rain was heaviest in upland western districts with 90mm in 72h at Capel Curig (Snowdonia) of which 59mm fell on the 23rd alone, but amounts in eastern and southern England were derisory, and a few locations escaped altogether. High pressure re-established itself over the UK on the 26th, migrating to northern Scotland during the last few days of the month, and it became mostly fine and warm except near North Sea coasts which were plagued by haar. Districts bordering the Solent were particularly favoured with highs of 22-25°C on each of the last four days. Mean maximum temperature for April was well above normal everywhere, the anomaly ranging from +1.5degC in Shetland to +6degC locally in Sussex and Hampshire. Mean minimum temperature was 2 to 3 degC above in all regions. It was the warmest April in the entire Central England Temperature series which began in 1659, beating the previous warmest, 1865 (which had 10.6°C), by a wide margin. This is the third monthly record equalled or beaten in the last ten months. April also ranked eighth driest in a record going back to 1766, and second sunniest (after 1893) in a series which began in 1881. Large parts of the UK had no significant rain (i.e. no day with more than 0.2mm) over a period of 25-30 days beginning in late-March, and at a small number of sites there was no rain at all during the month.
Text Box: High pressure lay over or close to the British Isles throughout the month, apart from the 21st-25th when a rather humid south to southwesterly airflow covered the country. Mean sea-level pressure was well above normal, anomalies ranging from +6mbar at Valentia and Scilly to +9mbar on the Northumberland coast; overall it was the eleventh most anticyclonic April in 134 years of records. Highest pressure lay over Scotland and southern Scandinavia as the month began, but the anticyclone migrated to the west of Scotland between the 2nd and 4th, thence to Ireland and southern Britain from the 5th to the 11th, returning to southern Scandinavia between the 13th and 16th. The opening days were warm and sunny by day in spite of a stiff easterly wind over England and Wales, but cold and frosty at night especially in Scotland where the month’s lowest temperature of -5.6°C was recorded at Tulloch Bridge (Lochaber) and Kinbrace (Sutherland) early on the 1st, but afternoon highs of 17-20°C were typical in southern England. It was briefly colder and cloudier on the 3rd with maxima of 6 to 9°C over much of eastern England, but warm and sunny weather soon returned to most parts of the UK although nights were frosty in many places; a noteworthy diurnal range of 22.8 degC (-1.8 to 21.0°C) was logged on the 4th at Aboyne (Aberdeenshire). A potent Arctic outbreak which affected northern and eastern Europe from the 5th to 7th grazed Shetland bringing some outbreaks of snow here, while afternoon temperatures close to 5°C at Lerwick contrasted with 15-20°C over much of the rest of the UK. The next few days were cloudy with occasional rain in northwest Scotland, but the sunshine continued elsewhere: Ronaldsway (Isle of Man) measured 77.6h of bright sunshine during the first week and Camborne (Cornwall) 97.3h between the 1st and 10th. It became very warm between the 14th and 16th, the temperature widely reaching 21-25°C; Lee-on-Solent recorded 25.0°C on the 14th and 25.5°C on the 16th, while the month’s highest reading of 26.5°C was observed at Herstmonceux (Sussex) on the 15th. A few showers, locally accompanied by thunder, affected southwest England, Wales and the Channel Isles around this time.