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graphs      CLIMATE-UK.COM'S  REVIEW  OF  THE  BRITISH  METEOROLOGICAL  SCENE
     MONTHLY  SUMMARY
     No. 568               MOSTLY DRY, WARM AND SUNNY            For    APRIL    2003
Text Box: Anticyclonic conditions prevailed until the 23rd, but the last week of the month was markedly cyclonic. Mean sea-level pressure ranged from 2.5 mbar above normal in Shetland to 2 mbar below in southwest Ireland, resulting in a southeasterly anomalous flow over the British Isles. A trough moved southeast across the country on the 1st followed by a cool northwesterly airflow, but pressure quickly rose again and an anticyclone lay over or close to the UK from the 3rd to the 8th, and a weak ridge of high pressure persisted until the 11th. A belt of rain moved southwards across all areas on the 1st followed by a cool day on the 2nd with sunny spells, wintry showers and isolated thunderstorms. The next three days were generally warmer and mainly dry; maxima of 18-21°C occurred in some areas. From the 7th to the 11th most southern, central and eastern districts were cold with maxima of 5-8°C in many places, and there were hail and snow showers on the 9th and 10th; meanwhile parts of Scotland and Northern Ireland continued relatively warm and sunny. Sharp overnight frosts occurred widely with temperatures dropping to -4 or -5°C in the coldest spots in northern England, the Midlands and Wales. From the 12th to the 17th the British Isles were sandwiched between low pressure off southwest Ireland and high pressure over the Baltic, resulting in a warm southeasterly airflow over the country. It became generally cloudy for two or three days and rain in western and northern regions deposited substantial amounts of Saharan dust, but it was much warmer than the preceding week and overnight minima of Text Box: 13-14°C on some western coasts were exceptionally high for April. After the 14th it became clear and sunny with maxima of 22-26°C widely reported from the 15th to the 18th. The high of 27.4°C at Stratfield Mortimer (Berks) on the 16th was the highest anywhere in the UK in April since 1949, the 27°C the same day at Prestatyn (Flintshire) was the highest in Wales since 1893, and the 26.9°C recorded at Lochcarron on the 17th established a new Scottish record for the month. The airflow backed easterly from the 18th to the 20th, and eastern and central regions became much cooler and cloudier. A shallow northward-moving depression on the 20th-21st was followed by a short-lived ridge of high pressure, but active Atlantic disturbances crossed the country at frequent intervals from the 24th onwards. Showers and thunderstorms were well-scattered at first, although 39mm fell at Aboyne (Aberdeenshire) on the 21st, but rain fell much more widely on the 24th and 25th; at Loftus (N.Yorks) rain on the 24th ended a 42-day period with no significant rain. The rest of the month was very disturbed with belts of rain alternating with brighter showery weather - even the showers were often heavy with hail and thunder; over 100mm fell at Cardinham (Cornwall) during the last week. It was the warmest April, averaged nationally, since 1987, the driest since 1997, and the sunniest since 1990. Mean maximum temperatures were 2-3 degC above normal and mean minima around 1 degC above. Over England and Wales rainfall averaged 20 per cent below the long-term average, while sunshine was 25-30 per cent above.
                                                                                                                                           
                       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   14.7   +2.3   05.7   +1.3   25.1   16   -01.2   09   14   04   00   10.6   16   163   128   1910   240   1912   087   1920   20   07.2   27   027   048   1910   123   2000   02   1912   01   01   00  
  Thorney Island   14.7   +1.3   06.0   +1.2   23.9   16   -01.9   10   11   03   01   12.2   17   201   114   1956   262   1990   101   1966   19   09.8   25   035   078   1941   111   2000   <01   1984   00   01   00  
  *Coltishall   13.7   +2.1   04.9   +0.9   24.5   16   -01.1   08   08   02   01   12.4   16   192   133   1979   257   1990   125   1981   22   07.8   01   032   078   1964   107   1981   04   1974   00   02   00  
  *Wittering   14.4   +2.6   04.9   +1.1   26.0   16   -02.1   08   13   04   01   12.3   16   187   128   1950   221   1984   077   1978   21   05.4   01   019   048   1948   142   1998   05   1954   00   02   00  
                                                                     
  Lyneham   14.5   +2.5   04.6   +0.7   25.3   16   -03.7   09   10   05   02   12.7   16   192   123   1952   243   1984   084   1961   18   06.8   27   038   084   1946   153   2000   01   1984   00   01   00  
  Ross-on-Wye   15.3   +3.0   05.0   +0.3   26.0   16   -03.0   09   12   04   01   11.8   16   195   135   1915   226   1984   072   1920   19   08.4   27   033   075   1859   173   2000   00   1957   00   01   00  
  *St Athan   14.8   +2.8   05.8   +1.3   24.7   17   -01.5   10   09   02   01   12.1   17   181   108   1954   253   1984   091   1966   20   12.0   27   044   083   1954   125   2000   02   1957   00   00   00  
  St Mawgan   14.0   +2.3   06.9   +1.4   23.9   17   00.6   09   04   00   01   13.1   17   222   116   1944   266   1984   125   1966   19   10.2   27   049   095   1945   142   1998   02   1984   00   00   00  
                                                                     
  *Edgbaston   13.9   +2.4   05.5   +1.0   24.9   16   -02.6   09   11   02   01   11.9   16   187   137   1887   235   1893   091   1891   20   07.6   27   035   079   1887   137   1998   02   1938   00   01   00  
  Valley   13.5   +2.0   06.4   +1.1   22.6   16   00.0   10   06   00   02   12.2   16   203   110   1946   247   1974   123   1996   16   22.4   27   055   106   1941   103   1961   07   1980   00   00   00  
  Ringway   14.8   +2.8   05.6   +1.2   25.1   16   -02.2   10   09   03   00   12.3   16   193   137   1945   216   1984   095   1961   20   14.6   27   057   114   1942   107   2001   04   1980   02   00   00  
  *Watnall   14.4   +2.6   05.0   +1.2   25.6   16   -01.7   10   10   02   02   12.1   16   158   108   1948   220   1984   071   1971   19   17.4   27   034   086   1942   135   2000   06   1957   01   01   00  
                                                                     
  *Leeming   14.9   +3.1   03.6   0.0   24.6   16   -03.0   10   11   05   02   12.3   16   195   145   1945   199   1984   088   1971   20   09.4   26   029   075   1945   140   2000   05   1954   00   01   00  
  *Boulmer   11.7   +1.5   04.8   +1.2   15.9   03   -01.2   10   09   02   03   12.3   23   185   127   1945   218   1984   083   1974   19   05.6   25   020   051   1945   156   1998   03   1980   00   00   00  
  Eskdalemuir   13.2   +2.8   03.6   +2.0   23.8   16   -04.5   10   12   06   04   13.0   17   189   140   1911   197   1942   059   1996   19   14.4   28   066   077   1911   254   1947   17   1980   01   01   00  
  *Bishopton   14.1   +2.1   04.9   +1.5   23.8   16   -01.4   10   16   01   04   12.7   17   182   119   1921   205   1962   073   1937   19   13.4   25   054   108   1921   159   1947   05   1974   00   00   00  
                                                                     
  Leuchars   12.0   +0.9   04.3   +1.0   17.7   03   -01.2   10   13   02   04   13.1   23   200   123   1922   217   1990   098   1937   19   12.8   25   039   099   1922   117   1934   02   1938   00   00   00  
  Dyce   11.6   +1.1   04.5   +1.9   18.6   16   -02.8   10   10   02   03   12.5   23   166   112   1941   212   1942   085   1941   20   15.8   21   055   110   1941   131   2000   10   1946   00   01   00  
  *Stornoway   12.9   +2.9   06.6   +3.1   20.8   18   01.2   09   06   00   02   13.2   14   170   108   1880   230   1962   095   1944   14   06.2   28   032   048   1943   144   1947   01   1974   00   00   00  
  *Aldergrove   13.5   +1.9   05.5   +1.0   21.2   17   -01.2   11   08   02   03   12.7   19   176   108   1927   220   1974   057   1937   19   07.2   27   032   069   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.