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graphs CLIMATE-UK.COM'S REVIEW OF THE BRITISH METEOROLOGICAL SCENE
MONTHLY SUMMARY
No. 665 For MAY 2011
EXCEPTIONALLY WET IN WESTERN SCOTLAND; VERY DRY IN EAST ANGLIA AND KENT
Text Box: During first few days of May a large blocking anticyclone lay in Arctic latitudes with strong easterly winds affecting the UK.  From the 4th-10th a deep depression sat to the west of Ireland with southerly winds across the country,  and from the 11th onwards lowest pressure was found to the west and north of Scotland with westerly and southwesterly winds delivering copious amounts of rain to the western highlands, Cumbria, and parts of Northern Ireland. Over the British Isles this was the fourth most southwesterly May in 138 years of records.

The opening days were mostly dry and sunny with low humidity and a stiff north-easterly wind, and there were several reports of heath and woodland fires around the UK. The West Country had some thundery rain on the 1st and 2nd; a severe thunderstorm was reported from Penzance on the evening of the 1st with 30mm of rain, most of which fell in 45 minutes. It was cool along the North Sea coast, but in the Scottish highlands days were warm and nights cold and frosty. The sun shone for 15.0h at Tiree (Inner Hebrides) and Kinloss (Morayshire) on the 3rd, while early on the 4th the temperature fell to -6.3C at Altnaharra (Sutherland). Winds veered towards the south on the 4th and 5th, bringing a rise in temperature to southern and eastern districts, but rain penetrated some western and northern parts of the country. It was very warm on the 6th and 7th with 25.3C at St James's Park (London) and 25.4C at Weybourne (Norfolk) on the respective dates and a minimum overnight 7th/8th of 16.0C at Weybourne. Outbreaks of heavy rain spread erratically eastwards to much of the UK on the 7th, with 40mm collected at Millport (Great Cumbrae, Firth of Clyde), but amounts of rain east roughly of the Greenwich meridian were very small. From the 8th-10th the weather was changeable, warm, and rather windy, but eastern, central and southern England remained largely dry.

Between the 11th and 20th winds varied between southwesterly and northwesterly bringing frequent changes in the weather. In northern and western Scotland, Northern  
Ireland, and Cumbria there were substantial falls of rain each day, but once again Text Box: eastern, central and southern England had trivial amounts.There was a good deal of sunshine at times, especially on the 12th, 13th, 14th and 19th, and temperatures remained a little above the seasonal average.

The 20th and 21st were warm with sunny periods in eastern and southern districts, the temperature reaching 23.1C at Lynford (Norfolk) on the 21st, but a deep depression brushed past northwest Scotland on the 22nd, bringing strong winds and heavy rain to northern regions, and an even deeper depression, 976mbar at its deepest, took an almost identical track on the 23rd, bringing the severest May gale to Scotland, Northern Ireland and northern England since 1962. Peak gusts at low-level sites included 70kn at Inverbervie (Kincardineshire) and 67kn at Drumalbin (Lanarkshire). Two people died and 30,000 homes were temporarily without power. At Cluanie Inn (Wester Ross) 56mm of rain fell on the 23rd alone, with 135mm during the 72h to 09GMT on the 24th. The 25th was a bright and rather warm day in central and eastern regions, but a further depression tracked across Northern Ireland and southern Scotland on the 26th, bringing heavy showers accompanied locally by thunder and hail even to East Anglia and the Southeast. Atlantic fronts brought further general rain during the 29th/30th (overnight 30th/31st in East Anglia, Essex and Kent), but the 31st was a day of scattered showers and sunny intervals.

Mean maximum temperature ranged from near normal in western Scotland to 2.5 degC above in East Anglia, while mean minima were 1-2 degC above in all regions. Several sites in East Anglia, the Midlands and Southeast England reported lower monthly temperatures in May than in April - unusual, but not without precedent. Rainfall percentages ranged from over 300 locally in western Scotland to less than 25 in East Anglia and Kent, with monthly totals ranging from 468mm at Cluanie Inn to 4mm at Manston (Kent). At Cluanie Inn daily totals exceeded 10mm on 20 of the 24 days ending 1st June. Sunshine percentages ranged from about 70 in southwest Scotland, northwest England and north Wales to 125 in the east of East Anglia and east Kent.
                                                                                                                                             
    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   18.2   +2.2   08.5   +0.9   24.2   06   02.7   04   05   00   00   12.0   25   196   108   1910   297   1989   112   1932   14   11.9   26   025   043   1910   124   1979   04   1989   01   00   00  
  *Thorney Island   16.8   +0.2   09.3   +1.8   19.8   16   03.0   04   00   00   00   13.7   10   266   116   1958   322   1989   151   1981   23   18.0   07   030   067   1941   103   1946   04   1989   00   00   00  
  *Wattisham   18.2   +2.6   07.8   +1.6   22.4   06   01.2   04   04   00   00   14.2   03   248   130   1968   331   1989   127   2006   18   05.2   30   015   034   1960   119   2007   05   1989   00   00   00  
  *Wittering   17.7   +2.5   07.7   +1.1   22.9   06   01.7   04   02   00   01   13.9   03   203   100   1955   299   1989   113   2007   23   08.8   30   023   048   1955   116   1983   09   1990   00   00   00  
                                                                     
  *Lyneham   16.9   +1.5   07.9   +1.3   22.8   06   01.0   04   01   00   00   13.6   02   196   098   1945   288   1990   112   1981   14   14.4   07   047   081   1945   139   1967   05   1990   00   00   00  
  Ross-on-Wye   17.7   +2.0   08.6   +1.4   24.5   06   01.9   03   01   00   00   13.2   02   212   113   1915   285   1992   104   1932   10   18.4   07   042   069   1859   158   1967   05   1896   00   00   00  
  *St Athan   16.0   +1.0   09.4   +2.1   20.6   06   03.7   04   01   00   02   12.3   03   166   080   1954   318   1990   119   1981   13   14.0   09   063   101   1954   155   1983   05   1991   00   00   00  
  Culdrose   14.7   +1.2   09.6   +1.3   17.5   07   05.9   25   01   00   02   13.1   31   162   072   1961   275   2004   124   1981   15   08.8   01   029   048   1961   141   1993   06   1991   00   00   00  
                                                                     
  *Edgbaston   16.7   +1.2   08.4   +1.5   22.0   06   03.3   03   00   00   00   13.5   03   167   100   1887   263   1997   094   1954   17   17.0   07   062   110   1887   173   1932   05   1896   01   00   00  
  *Valley   15.0   +0.7   09.7   +1.9   19.9   07   04.7   04   00   00   02   13.7   02   175   077   1946   306   1977   161   1970   13   26.8   07   078   139   1941   127   1993   10   1970   00   00   00  
  *Woodford   16.1   +1.0   08.0   +1.6   21.5   06   01.5   04   05   00   01   13.6   01   136   077   1945   258   1989   111   1991   07   09.2   07   065   108   1942   144   1967   08   1991   01   00   00  
  *Watnall   16.9   +1.7   08.1   +1.5   22.0   06   00.1   04   01   00   03   13.7   01   169   083   1948   276   1989   085   1983   16   14.8   07   045   097   1942   135   1969   11   1991   02   00   00  
                                                                     
  *Leeming   17.0   +2.0   07.1   +0.8   21.9   09   -02.0   04   08   02   00   14.3   01   190   107   1945   238   1980   103   1983   12   14.0   07   028   057   1947   106   1983   09   1959   02   00   00  
  *Boulmer   15.4   +2.9   07.5   +1.7   18.6   06   01.5   04   01   00   00   13.1   01   173   098   1945   231   1989   098   1983   11   18.0   07   044   085   1945   151   1924   07   1992   00   00   00  
  *Eskdalemuir   13.3   -0.3   05.6   +1.5   18.1   07   -02.3   04   07   03   03   13.7   01   120   072   1911   268   1935   079   1969   04   38.0   21   225   237   1911   257   1986   04   1984   01   00   00  
  *Bishopton   14.5   -0.5   07.0   +1.0   20.2   07   00.4   04   04   00   04   14.7   02   154   082   1921   266   1975   098   1983   04   29.4   21   149   237   1921   156   1925   07   1991   00   00   00  
                                                                     
  *Leuchars   15   +1.6   06.2   +0.4   18.5   16   -01.4   04   12   01   01   14.2   01   203   108   1922   256   1942   095   1969   12   28.6   07   092   180   1922   152   1969   14   1959   00   00   00  
  *Dyce   14.6   +1.8   06.3   +1.2   17.0   16   -01.9   04   06   02   04   14.2   03   185   106   1941   256   2001   086   1983   12   13.8   08   051   084   1942   152   1969   14   2008   00   00   00  
  *Stornoway   13.0   +0.8   07.1   +1.1   18.4   07   03.6   04   01   00   03   14.6   01   162   086   1880   294   1994   093   1944   04   18.4   31   * 154   249   1943   145   1986   13   2008   00   00   00  
  *Aldergrove   14.6   -0.1   08.4   +2.3   18.8   01   05.6   31   00   00   03   14.1   01   152   076   1927   295   1946   115   1933   11   09.8   07   059   113   1927   131   1993   07   1991   00   00   00  
                                                                     
                                                                                                                                             
  Stations marked with an asterisk record sunshine electronically; comparisons      
  with earlier records are therefore somewhat speculative.     * New high record