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graphs      CLIMATE-UK.COM'S  REVIEW  OF  THE  BRITISH  METEOROLOGICAL  SCENE
     MONTHLY  SUMMARY
     No. 629       For     MAY      2008
         VERY WARM;  DRY AND SUNNY IN THE NORTH; A DULL, WET LAST WEEK IN THE SOUTH
Text Box: High pressure lay to the north of the UK, either in the Iceland/Greenland region or over Scandinavia, throughout the month. Pressure was frequently low over mid-Atlantic, and during the last week over Biscay and France. The main sea-level pressure anomaly centres were +8mbar in the southern Norwegian Sea and -7mbar to the west of Biscay, resulting in a marked east to south-easterly anomalous flow over the British Isles. In fact, this was the most ‘easterly’ May in 136 years of records.

The early-morning of the 1st was wet over Scotland (the rainfall credited to 30 April) as a vigorous depression moved away northwards; a very warm but cloudy south to south-easterly airflow developed over the next few days, and there was further rain at times chiefly in western districts, but in eastern and central England it was largely dry. A long period with maxima widely above 20°C began on the 3rd, while several nights were unusually mild too.  Most parts of the UK were very warm and sunny from the 5th until the 13th as high pressure remained slow-moving firstly over the North Sea, and latterly near northern Scotland. The temperature climbed above 25°C somewhere in Britain daily from the 7th to the 13th, reaching 27.3°C at Herstmonceux (Sussex) on the 10th, 27.5°C at Malvern (Worcs) on the 11th, and 26.9°C at Lee-on-Solent (Hants) on the 12th. The warmest nights were those of the 9th/10th and 10th/11th, and on the latter night the minimum at St Catherine’s Point (Isle of Wight) was 16.6°C. Norwich reported seven consecutive days each with more than 14 hours’ bright sunshine ending on the 12th, and the total for 1st-15th there was 165 hours, an average of 11 hours per day.

From the 14th to the 23rd pressure remained high to the north of Scotland, with a cool east to north-easterly flow covering the British Isles. Central and northern districts remained dry and mainly sunny, but there were occasional thundery outbreaks in southern England and south Wales, notably between the 14th and 17th, and St Mawgan (Cornwall) collected 41mm overnight 14th/15th. The month's lowest maximum of 8.2°C Text Box: occurred at Carter Bar (Roxburghshire) on the 17th, and there were sharp frosts at night especially in Scotland and northern England, and at Kinbrace (Sutherland) the temperature fell to -5.0°C early on the 18th and -6.2°C on the 19th. The north-easterly flow strengthened markedly between the 24th and 26th as a vigorous depression became slow-moving in north Biscay; on the 26th gusts to 64kn were recorded at Mumbles (Glamorgan) and 53kn at Pembrey Sands (Carmarthen). Heavy rain spread northwards across southern and central parts of England and Wales late on the 24th, and there were repeated bouts of heavy rain over the next five days including falls of 40mm at Thorney Island (Sussex) on the 25th and 39mm at Liscombe (Devon) on the 26th. Manston (Kent) collected 121mm in 84 hours between the 24th and 27th, and a further 25mm on the 29th. On the evening of the 29th thunderstorms broke out over the West Country leading to short-lived but severe local flooding, notably in the Crewkerne/Ilminster and Bruton/Castle Cary districts of south Somerset; 70mm fell in less than 4 hours at Batcombe. Rain finally reached Northern Ireland and Scotland on the 28th, ending a 23-day rainless period in several places here. There were further outbreaks of showery rain with local thunder, notably in southwest England, on the 30th and 31st.

Mean temperatures were 2 to 3 degC above normal over much of the UK, apart from eastern Scotland and northeast England where the excess amounted to 1 to 2 degC. As measured by the Central England Temperature, it was the warmest May, with the exception of 1992, since 1848. The heavy rains of the last week ensured that all southern districts were wetter than normal for the third consecutive May, but northern England, Scotland and Northern Ireland were all exceptionally dry with monthly totals of just 5-10mm reported from a number of sites. Sunshine duration was 50 to 80 per cent above normal in the north and west of Scotland, but up to 30 per cent below in the English midlands; monthly totals ranged from 304 hours at Fair Isle to 135 hours at Coleshill (Warwks).
                                                                                                                                             
                       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   18.9   +2.9   09.6   +2.0   25.6   11   03.5   19   01   00   05   11.7   06   176   097   1910   297   1989   112   1932   20   23.5   26   091   165   1910   124   1979   04   1989   01   00   00  
  *Thorney Island   19.0   +2.4   10.2   +2.7   25.9   10   03.8   02   02   00   03   13.8   21   219   101   1958   322   1989   151   1981   19   39.8   25   088   211   1941   103   1946   04   1989   00   00   00  
  *Wattisham   18.1   +2.5   08.7   +2.5   25.8   10   01.2   20   02   00   05   13.3   08   218   114   1968   331   1989   127   2006   19   31.2   26   068   163   1960   119   2007   05   1989   00   00   00  
  *Wittering   17.8   +2.6   08.6   +2.0   24.0   10   02.4   20   04   00   03   14.4   06   171   084   1955   299   1989   113   2007   18   18.0   25   073   164   1955   116   1983   09   1990   00   00   00  
                                                                     
  Lyneham   17.8   +2.4   09.0   +2.4   25.2   11   02.5   19   04   00   05   14.0   07   173   086   1945   288   1990   112   1981   20   18.0   25   056   101   1945   139   1967   05   1990   01   00   00  
  Ross-on-Wye   18.5   +2.8   09.7   +2.5   26.0   11   04.0   02   00   00   06   12.9   06   167   089   1915   285   1992   104   1932   19   22.4   15   098   171   1859   158   1967   05   1896   01   00   00  
  *St Athan   17.8   +2.8   10.2   +2.9   24.7   11   06.1   19   00   00   04   13.0   07   172   083   1954   318   1990   119   1981   16   19.8   28   073   123   1954   155   1983   05   1991   02   00   00  
  St Mawgan   17.1   +3.0   10.4   +2.4   24.5   12   05.6   20   00   00   04   13.8   19   209   094   1956   297   1990   125   1981   15   41.2   14   124   213   1956   149   1981   07   1991   01   00   00  
                                                                     
  *Edgbaston   17.5   +2.0   09.2   +2.3   25.4   11   01.9   20   02   00   04   15.3   14   180   107   1887   263   1997   094   1954   19   18.2   27   079   148   1887   173   1932   05   1896   00   00   00  
  *Valley   17.5   +3.2   10.3   +2.5   24.9   08   05.8   19   00   00   02   15.2   31   232   103   1946   306   1977   161   1970   23   06.6   22   028   051   1941   127   1993   10   1970   00   00   00  
  *Woodford   17.9   +2.8   08.9   +2.5   25.4   11   01.2   19   05   00   05   14.4   14   168   095   1945   258   1989   111   1991   22   13.6   27   034   060   1942   144   1967   08   1991   00   00   00  
  *Watnall   17.7   +2.5   08.2   +1.6   24.8   11   01.8   20   05   00   04   13.1   11   151   074   1948   276   1989   085   1983   22   17.8   26   063   141   1942   135   1969   11   1991   00   00   00  
                                                                     
  *Leeming   16.8   +1.8   06.8   +0.5   23.7   10   00.4   19   06   00   06   13.8   08   190   107   1945   238   1980   103   1983   20   13.2   29   032   068   1947   106   1983   09   1959   00   00   00  
  *Boulmer   13.3   +0.8   07.4   +1.6   15.4   29   02.1   20   00   00   05   13.5   19   179   101   1945   231   1989   098   1983   20   04.8   28   015   030   1945   151   1924   07   1992   00   00   01  
  *Eskdalemuir   16.1   +2.5   06.6   +2.5   22.7   09   -00.7   18   05   02   03   12.7   08   149   090   1911   268   1935   079   1969   21   20.8   10   038   042   1911   257   1986   04   1984   00   00   00  
  *Bishopton   16.9   +1.9   08.2   +2.2   22.4   31   03.6   18   01   00   02   14.8   26   170   091   1921   266   1975   098   1983   21   08.6   28   022   036   1921   156   1925   07   1991   00   00   00  
                                                                     
  *Leuchars   13.8   +0.4   07.3   +1.5   17.4   29   00.9   19   06   00   02   14.3   26   184   098   1922   256   1942   095   1969   21   05.4   28   019   038   1922   152   1969   14   1959   00   00   00  
  *Dyce   14.0   +1.2   06.8   +1.7   17.9   29   00.3   19   08   00   04   14.1   08   169   097   1941   256   2001   086   1983   18   07.4   28   * 014   025   1942   152   1969   14   1994   00   00   00  
  *Stornoway   14.5   +2.3   08.0   +2.0   20.4   07   04.5   18   00   00   01   15.4   26   286   151   1880   294   1994   093   1944   24   06.6   28   * 013   022   1943   145   1986   19   1978   00   00   00  
  *Aldergrove   17.4   +2.7   08.4   +2.3   22.9   31   04.2   19   01   00   03   15.4   31   234   118   1927   295   1946   115   1933   21   02.6   28   008   017   1927   131   1993   07   1991   00   00   00  
                                                                     
                                                                                                                                             
  Stations marked with an asterisk record sunshine electronically; comparisons      
  with earlier records are therefore somewhat speculative. Thorney Island's     * New or equal lowest  
  sunshine figures are from a nearby site.