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graphs      CLIMATE-UK.COM'S  REVIEW  OF  THE  BRITISH  METEOROLOGICAL  SCENE
     MONTHLY  SUMMARY
     No. 652            For    APRIL    2010
A DRY AND VERY SUNNY MONTH OVER ENGLAND AND WALES; WARM DAYS BUT RATHER COLD NIGHTS
Text Box: Although the first week was changeable and rather cold, and the last week changeable and rather warm, the greater part of the month was quiet and anticyclonic with abundant sunshine, warm days, and cool nights. Mean monthly sea-level pressure was between 2 and 4mbar above normal over most of the country. April opened with the depression responsible for the late-March highland snowstorm centred off Aberdeen, and a brisk northwesterly airstream covering the UK. A further complex depression moved slowly eastwards across the country between the 2nd and 4th, but the next Atlantic system curved northwards towards Iceland as pressure rose strongly over the near continent. The 1st was a cold day with hail and sleet showers, and at Aviemore snow lay 39cm deep from the previous day's fall. Over the next three days there were further outbreaks of rain, heavy at times, over much of the country, with 31mm at Portland (Dorset) on the 3rd and 35mm at Threave (Galloway) on the 4th. It remained rather cold, especially in Scotland where Braemar (Aberdeenshire) dropped to -7.0°C early on the 2nd, and Cromdale (Strathspey) climbed no higher than 2.5°C that afternoon. It became mostly dry and warmer on the 5th and 6th over much of England, but western and northern regions were wet and windy with over 40mm locally in the western highlands, and a peak gust of 59kn at Capel Curig (Snowdonia), and Aviemore's snow-cover finally disappeared on the afternoon of the 5th. A weakening cold front brought light rain and a drop in temperature to central and eastern England on the 7th. From the 8th until the 24th high pressure controlled the UK's weather, the high centre transferring from England to Scotland, then to mid-Atlantic from the 13th, although a strong ridge was maintained across the British Isles for another ten days. From the 8th till the 16th it was dry almost nationwide, but from the 17th-24th there was rain from time to time Scotland and Northern Ireland, and occasionally also in northern and eastern England. Most days were sunny over a
Text Box: large part of the country, although the 14th was rather cloudy, and on the 17th Coleshill (Warwicks) logged 13.9h, the month's highest. Daytime temperatures were rather variable, but it was very warm in Scotland between the 10th and 12th with 21.1°C at Cromdale on the 11th, and it was warm across England around the 16th-18th and 23rd-24th with 21.3°C at St James's Park (London) on the 24th. By contrast, northern Scotland was cold from the 17th-24th with snow showers over the highlands and the Northern Isles, and Loch Glascarnoch (Wester Ross) only reached 2.5°C on the 23rd. Nights were often cold with air frost occurring quite widely on several occasions, with a notable -6.1°C at Katesbridge (Co Down) early on the 21st. An eastward-moving cold front on the 25th was followed by a ridge of high pressure, but further fronts crossed the British Isles during the last few days of the month. Most districts were quite warm until the 28th when Gravesend/Broadness (Kent) reached 22.1°C, and the Southeast remained warm for a further day. Most places had a short spell of rain on the 25th, with thunder reported locally, and there were further outbreaks of rain or showers during the last three days of the month, but scattered location in central and southern England had no measurable rain from the 4th-29th inclusive. Mean maximum temperature ranged from 0.5degC above the 1971-2000 average in northern and western Scotland, to 2.5-3.0degC above in parts of the Midlands and the South. By contrast, mean minimum temperature was within 0.5degC of the average in nearly all regions. With the exception of western Scotland it was a dry month, and less than 20% of the normal rainfall was registered at several sites in East Anglia, the east and south Midlands, and the northern Home Counties. Writtle (Essex) and Durham University recorded just 8mm. As for sunshine, this month ranked fifth sunniest over England and Wales in the last 100 years, after 1912, 1914, 1984 and 2007. Jersey airport recorded a monthly sunshine total of 279 hours and Guernsey airport 275 hours.
                                                                                                                                             
                       TEMPERATURE                                SUNSHINE                             RAINFALL        
                                                                                                                                     
                                                                                                                                     
                                          Highest and lowest totals                     Highest and lowest totals        
                                              on record for month    
Maximum fall in 24 hrs (beginning 09 h)
                    on record for month    
Days with snow or sleet
 
Days with fog (Vis <220 yards at 09 h)
 
                                                                                         
     
Difference from average
   
Difference from average
 
Highest maximum
   
Lowest minimum
   
No. of days with grass minimum below 0ºC
   
Days of no sunshine
 
Maximum duration
       
First year of record
         
Days of no rainfall (0.1 mm or less)
         
First year of record
         
Days with thunder
     
       PLACE  
Mean Maximum
   
Mean minimum
             
No. of air frosts
       
Total for month
                   
Total for month
                   
                               
% of average
                   
% of average
                 
                                                                     
                                   
Highest
   
Lowest
 
Year
             
Highest
   
Lowest
 
Year
       
             
Date
   
Date
         
Date
         
Year
         
Date
         
Year
           
                                                                     
      ºC       ºC       ºC       ºC             Hrs       Hrs         Hrs       Hrs       mm       mm         mm     mm          
                                                                                                                                             
  *Hampstead   14.9   +2.6   05.1   +0.8   20.6   28   00.7   01   13   00   00   10.9   18   190   147   1910   240   1912   087   1920   21   07.9   30   025   048   1910   123   2000   02   1912   00   00   00  
  *Thorney Island   13.6   +0.2   04.7   -0.1   17.0   26   00.3   23   10   00   00   13.8   17   258   150   1956   262   1990   101   1966   20   08.8   02   020   041   1941   111   2000   00   2007   00   00   00  
  *Wattisham   13.9   +1.8   04.1   +0.6   20.1   28   -00.5   22   10   03   01   12.6   23   210   150   1968   254   1990   123   2006   19   02.8   29   015   035   1960   109   1998   02   2007   00   00   00  
  *Wittering   14.2   +2.4   04.2   +0.4   19.7   28   00.1   21   08   00   01   12.2   17   200   136   1950   221   1984   077   1978   22   04.4   30   017   038   1948   142   1998   03   2007   00   00   00  
                                                                     
  Lyneham   14.0   +2.0   04.0   +0.1   19.8   28   -00.1   08   13   01   01   12.8   17   225   143   1952   243   1984   084   1961   27   13.2   03   018   037   1946   153   2000   01   1984   00   00   00  
  Ross-on-Wye   14.6   +2.3   03.4   -1.3   20.8   24   -00.2   17   11   01   00   12.7   16   184   127   1915   229   2007   072   1920   19   07.1   02   021   042   1859   173   2000   00   1957   00   00   00  
  *St Athan   13.5   +1.5   04.9   +0.4   19.6   28   01.2   21   10   00   03   12.8   20   222   131   1954   253   1984   091   1966   20   05.2   29   023   040   1954   125   2000   02   1957   00   00   00  
  Culdrose   12.4   +1.1   05.3   -0.3   16.3   27   01.0   18   10   00   03   12.5   10   207   121   1961   248   1984   127   1966   19   06.2   01   030   051   1961   152   1998   09   1984   00   00   00  
                                                                     
  *Edgbaston   13.8   +2.5   05.4   +1.2   19.6   24   01.3   01   04   00   00   11.4   21   172   137   1887   242   2007   091   1891   22   06.2   01   024   035   1887   137   1998   02   1938   00   00   00  
  *Valley   12.1   +0.6   05.5   +0.2   17.3   10   00.1   22   12   00   00   12.8   17   223   120   1946   247   1974   123   1996   21   06.8   04   017   030   1941   103   1961   07   1980   00   00   00  
  *Woodford   14.0   +2.3   02.9   -0.7   18.9   10   -03.7   21   19   09   01   13.1   21   162   123   1945   216   1984   095   1961   15   06.1   29   028   051   1942   107   2001   04   1980   00   00   00  
  *Watnall   14.0   +2.2   04.5   +0.7   19.5   28   00.3   22   10   00   01   12.8   17   159   108   1948   220   1984   071   1971   17   13.8   30   038   085   1942   135   2000   06   1957   00   00   00  
                                                                     
  *Leeming   13.9 ZZ +2.1   03.3   -0.3   22.0   28   -02.5   22   15   05   02   12.7   17   149   110   1945   213   2007   088   1971   21   04.4   29   017   039   1945   140   2000   05   1954   00   00   00  
  *Boulmer   11.9   +1.7   04.6   +1.0   19.8   28   -01.4   02   07   02   03   12.3   21   129   089   1945   218   1984   083   1974   20   03.2   04   011   024   1945   156   1998   03   1980   00   00   00  
  *Eskdalemuir   11.7   +1.3   01.6   0.0   18.3   24   -04.8   22   20   08   04   11.9   16   135   099   1911   197   1942   059   1996   13   24.6   04   073   077   1911   254   1947   17   1980   00   02   00  
  *Bishopton   13.0   +1.0   04.4   +1.0   19.1   12   -02.3   02   10   03   02   13.2   16   166   107   1921   205   1962   073   1937   13   23.0   05   083   150   1921   159   1947   05   1974   00   00   00  
                                                                     
  *Leuchars   12.4   +1.3   04.0   +0.7   17.6   10   -03.6   02   20   03   02   12.7   16   161   099   1922   217   1990   098   1937   17   08.2   23   029   067   1922   117   1934   02   1938   00   00   00  
  *Dyce   12.0   +1.5   04.1   +1.5   18.0   16   -02.2   02   12   02   02   12.3   16   139   094   1941   212   1942   085   1941   15   07.8   30   036   064   1941   131   2000   10   1946   00   01   00  
  *Stornoway   10.3   +0.3   04.0   +0.4   15.0   11   -01.4   23   12   02   05   12.9   11   113   072   1880   230   1962   095   1944   07   12.4   27   072   098   1943   144   1947   01   1974   00   01   00  
  *Aldergrove   13.1   +1.2   04.3   +0.3   18.0   11   -00.9   21   13   04   01   12.4   11   149   099   1927   220   1974   057   1937   17   07.0   02   034   064   1927   117   1986   06   1938   00   00   00  
                                                                     
                                                                                                                                             
  Stations marked with an asterisk record sunshine electronically; comparisons      
  with earlier records are therefore somewhat speculative. Thorney Island's      
  sunshine figures are from a nearby site.