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graphs CLIMATE-UK.COM'S REVIEW OF THE BRITISH METEOROLOGICAL SCENE
MONTHLY SUMMARY
No. 664 For APRIL 2011
WARMEST SINCE BEFORE 1659 (ECLIPSING APRIL 2007); VERY DRY AND SUNNY EXCEPT IN NW SCOTLAND
Text Box: evening over England. Nevertheless this was the hottest day of the spell, with the somewhat sheltered site at Wisley (Surrey) recording 27.8C; this was the highest April temperature recorded anywhere in Britain since 1949. Highs of 25C or more were recorded as far north as Yorkshire and as far west as Somerset. Heavy thundery downpours led to short-lived localised flooding, notably in Sheffield, and hail was also reported.

It became rather less warm on the 24th and 25th with highest temperatures found along the south coast, and the 26th was a generally cloudy and rather cool day over the southern half of the country except along the south coast where some sites reported 12 consecutive days with 10h or more bright sunshine between the 17th and 28th, and Southampton logged an aggregate of 143h sunshine during this spell. In Scotland warm sunshine followed a frosty start, with -5.4C logged at Tulloch Bridge (Lochaber). There were further showers and a few thunderstorms (with local hail) in the south Midlands on the 29th and in southern counties of England on the 30th, but most places were dry, warm and sunny on the last day of the month in spite of a stiff northeast wind, and Kinloss (Moray) registered 14.7h bright sunshine - the month's highest daily figure.

Mean maximum temperature ranged from around 2degC above normal in northern and western Scotland to 5-6degC above in East Anglia and the Southeast, while mean minima were 3.5-4.5degC above normal in all regions. It was the warmest April in the entire 353-year long CET record by the relatively wide margin of 0.8degC, the previous record having been set only four years ago. Rainfall was below normal practically everywhere in the UK, and over much of eastern, central and southern England it was exceptionally dry with monthly totals of 5mm or less. Sunshine duration was up to 30 per cent above normal in western and northern districts, and 50-75 per cent above in East Anglia and Southeast England.
Text Box: A warm SW-ly flow prevailed for about a week, but high pressure lay over or close to the British Isles from the 7th-18th before transferring to the Baltic for several days. A new anticyclone developed over the country on the 25th, thence drifting northwards and allowing a strong easterly flow to develop.  Mean monthly sea-level pressure was 1-5mbar above normal over the UK, but the Icelandic Low was exceptionally deep for April with much mobility from Newfoundland to the Russian Arctic.

The month began with warm but changeable southwesterly winds. Amounts of rain were mostly small in eastern and southern districts, but there was prolonged and sometimes heavy rain over northern and western Scotland, Northern Ireland, northwest England and Wales. On the 4th, 61mm of rain fell at Capel Curig (Caernarfon), 59mm at Shap (Cumbria), and 53mm at Tyndrum (Stirlingshire), and a further 55mm fell at Tyndrum on the 5th. The eight-day total ending on the 6th at Tyndrum was 215mm. It was generally warm on the 1st and 2nd, and very warm on the 6th with temperatures widely in excess of 20C; 23.9C was recorded at Santon Downham (Norfolk). 

With high pressure now in charge, the warm weather lasted until the 11th and most parts of the UK became dry and sunny. Afternoon highs were typically between 18 and 22C, with a noteworthy 23.3C recorded as far north as Fyvie (Aberdeenshire) on the 10th, but ground frost occurred widely during this period. The 12th was mainly sunny over England and Wales but much cooler, while Scotland and Northern Ireland had heavy showers and most districts were cool and cloudy over the next two days. It gradually became warmer again from the 15th onwards with temperatures climbing a little each day, and a spell of exceptional warmth and sunshine lasted from the 19th-25th, and a remarkable diurnal range of 23.4degC was recorded at Santon Downham on the 21st. The fine spell was interrupted by some rain on the 23rd, Easter Saturday, in the north and west, and by scattered thunderstorms the same afternoon/
                                                                                                                                             
    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 0C
   
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
           
                                                                     
    C     C     C     C           Hrs     Hrs       Hrs     Hrs       mm     mm       mm     mm          
                                                                                                                                             
  *Hampstead   18.5   +6.2   08.0   +3.7   26.6   23   03.9   13   02   00   01   10.5   27   207   161   1910   240   1912   087   1920   25   01.8   04   003   006   1910   123   2000   02   1912   01   00   00  
  *Thorney Island   17.2   +3.8   07.6   +2.8   24.2   24   03.0   13   00   00   00   12.5   10   * 269   152   1956   262   1990   101   1966   23   02.4   29   005   011   1941   111   2000   00   2007   00   00   00  
  *Wattisham   17.8   +5.7   06.7   +3.2   25.6   23   01.1   13   05   00   02   12.7   30   224   160   1968   254   1990   123   2006   24   03.2   03   005   014   1960   109   1998   02   2007   00   00   00  
  *Wittering   17.6   +5.8   06.8   +3.0   25.5   23   01.8   13   02   00   01   12.3   08   214   146   1950   221   1984   077   1978   28   01.6   04   * 003   007   1948   142   1998   03   2007   02   00   00  
                                                                     
  *Lyneham   17.6   +5.6   06.9   +3.0   24.8   23   01.7   28   06   00   03   12.7   08   198   126   1952   243   1984   084   1961   23   02.6   03   005   011   1946   153   2000   01   1984   01   00   00  
  Ross-on-Wye   18.4   +6.1   06.6   +1.9   25.2   23   01.2   28   01   00   00   12.6   19   217   150   1915   229   2007   072   1920   25   00.8   03   002   004   1859   173   2000   00   1957   01   00   00  
  *St Athan   16.4   +4.4   08.1   +3.6   23.6   21   03.8   28   02   00   04   13.1   28   219   130   1954   253   1984   091   1966   20   04.0   04   009   018   1954   125   2000   02   1957   00   00   00  
  Culdrose   14.9   +3.6   08.3   +2.7   19.9   25   04.5   28   02   00   04   12.2   17   226   132   1961   248   1984   127   1966   22   10.6   30   020   038   1961   152   1998   09   1984   00   00   00  
                                                                     
  *Edgbaston   17.4   +6.1   08.0   +3.8   25.0   23   04.1   04   00   00   00   11.9   10   209   166   1887   242   2007   091   1891   26   03.0   03   004   006   1887   137   1998   02   1938   01   00   00  
  *Valley   14.7   +3.2   08.0   +2.7   22.7   21   03.2   24   02   00   05   13.6   28   210   113   1946   247   1974   123   1996   14   08.6   05   032   062   1941   103   1961   07   1980   00   00   00  
  *Woodford   16.8   +5.1   06.0   +2.4   23.2   21   -02.1   28   12   01   03   12.7   30   197   151   1945   216   1984   095   1961   23   04.8   04   012   024   1942   107   2001   04   1980   00   00   00  
  *Watnall   17.3   +5.5   07.0   +3.2   25.2   23   02.4   13   04   00   04   12.5   08   186   127   1948   220   1984   071   1971   27   02.4   04   * 003   008   1942   135   2000   06   1957   01   00   00  
                                                                     
  *Leeming   16.8   +5.0   05.2   +1.6   23.1   23   -00.9   28   10   01   00   13.4   30   * 222   165   1945   213   2007   088   1971   26   00.6   11   * 002   004   1945   140   2000   05   1954   01   00   00  
  *Boulmer   13.8   +3.6   06.5   +2.9   20.3   08   01.6   28   02   00   01   13.1   30   189   130   1945   218   1984   083   1974   19   03.4   01   011   028   1945   156   1998   03   1980   00   00   00  
  *Eskdalemuir   14.7   +4.3   04.4   +2.8   21.8   09   -01.1   24   09   03   05   13.7   28   * 198   146   1911   197   1942   059   1996   15   39.0   04   101   118   1911   254   1947   17   1980   00   00   00  
  *Bishopton   14.7   +2.7   06.1   +2.7   20.1   21   02.1   27   05   00   03   14.1   30   172   112   1921   205   1962   073   1937   17   22.2   04   064   128   1921   159   1947   05   1974   00   00   00  
                                                                     
  *Leuchars   14.3   +3.2   05.5   +2.2   21.0   10   -00.7   27   14   01   01   14.2   30   200   123   1922   217   1990   098   1937   26   04.6   23   008   021   1922   117   1934   02   1938   00   00   00  
  *Dyce   15.0   +4.5   05.6   +3.0   21.0   10   -01.1   27   08   01   00   14.0   30   182   122   1941   212   1942   085   1941   21   05.4   23   014   028   1941   131   2000   10   1946   00   00   00  
  *Stornoway   12.9   +2.9   06.9   +3.3   20.2   22   01.5   20   02   00   05   13.1   26   141   089   1880   230   1962   095   1944   12   10.0   04   051   077   1943   144   1947   01   1974   00   00   00  
  *Aldergrove   15.8   +3.9   07.1   +3.1   20.7   22   03.3   18   02   00   03   13.8   28   192   128   1927   220   1974   057   1937   17   06.4   12   020   042   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   * New record   * New record  
  sunshine figures are from a nearby site.