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graphs      CLIMATE-UK.COM'S  REVIEW  OF  THE  BRITISH  METEOROLOGICAL  SCENE
     MONTHLY  SUMMARY
     No. 592            For    APRIL    2005
          CHANGEABLE AND RATHER WET, BUT MOSTLY FINE IN SCOTLAND 16TH-26TH
Text Box: The month was characterised by enhanced cyclonic activity in the northern Atlantic, and mean sea-level pressure was below normal over much of northern and western Europe as well. The dominant anomaly centre was -7mbar just south of Iceland, while the anomalous flow over the British Isles was cyclonic/southwesterly. However, an easterly flow brought settled weather to much of Scotland between the 16th and 26th. High pressure persisted over Europe until the 5th; a mainly southerly flow covered the UK at first, veering westerly on the 4th and 5th. A vigorous depression then crossed the country followed by a brief northerly outbreak around the 8th, with westerlies returning from the 9th-12th. Much of Britain was fine and warm until the 3rd, the temperature widely reaching 17-20°C, and on the afternoon of the 2nd a patch of very dry air drifted north-westward across England with relative humidity around 20%. It turned cooler on the 4th with some showers, and wet and windy weather affected all areas on the 6th with gusts to 60kn; Capel Curig (Snowdonia) collected 59mm of rain in 48 hours. The rain-belt was followed by heavy showers accompanied by hail and thunder. The 7th and 8th were very cold with a strong to gale northerly wind, and the showers turned to snow even in the south. At Lerwick (Shetland) the maximum on the 8th was 0.1°C, the lowest in April there since 1985. The following night was frosty, and Benson (Oxon) logged -5.2°C. It turned warmer from the 10th as the flow backed westerly, and eastern and southern districts had long sunny periods. A mainly cyclonic period followed from the 13th to the 19th. A slow moving frontal system delivered prolonged heavy rain and hill snow on the 15th and 16th over northern England and southern Scotland; over the 48-hour period Boltshope Park (Durham) recorded 76mm and Newcastle 74mm. After a frosty start, further heavy rain spread from the west on the 17th giving 37mm at Lough Fea (Tyrone), while Bishopton (Renfrewshire) had 39mm on the 18th. Thunder and hail occurred somewhere over southern Britain almost daily during this period. Text Box: A strong ridge of high pressure extended southwards across northern Britain from the 20th to the 25th inducing an easterly flow over the UK but fronts were never far from southern districts. Scotland, Northern Ireland and northern England were largely dry with long sunny periods, and in the eight days ending on the 26th Kinloss (Moray) logged 89 hours’ bright sunshine and Stornoway (Western Isles) 88 hours. Nights were frosty but days were rather warm: Altnaharra registered a diurnal range of 21.9 degC (-4.6 to 17.3°C) on the 25th. Southern and central parts of England and Wales, meantime, were cloudier with occasional rain - heavy in the West Country on the 23rd with 40mm at Exmouth - but a patch of very dry air drifted across England from the continent on the 21st, the relative humidity dropping to 16% in London. The ridge declined on the 26th as a frontal trough advanced northwards across the country, and this was followed on the 28th by a vigorous depression. A sluggish southerly airflow developed on the 29th-30th. Belts of rain moved north-eastwards across all districts on the 26th followed by heavy showers and thunderstorms the next day, and widespread rain and gales on the 28th when Tyndrum (Perthshire) reported 42mm. Thereafter it became dry and warm in southern districts; the night of 29th-30th was unusually mild with minima widely of 12-13°C (the highest in April since 1945 locally), and a maximum of 22.7°C was recorded at Charlwood (Surrey) on the 30th. Mean monthly temperature ranged from near normal western and northern parts of the UK to almost 2 degC above at a few places in East Anglia and the Southeast. Averaged nationally it was a wet April and a number of sites in southern Scotland, northern England and Devon reported more than 2.5 times the normal rainfall. By contrast, just half the normal amount fell along the southern shore of the Moray Firth, while a relatively modest deficit in the London area meant that this was the 6th consecutive dry month here. Sunshine totals were mostly within 15 per cent of the average, but it was the dullest April since 1996 at Valley (Anglesey) with a 30 per cent deficit.
                                                                                                                                           
                       TEMPERATURE                                SUNSHINE                             RAINFALL