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graphs CLIMATE-UK.COM'S REVIEW OF THE BRITISH METEOROLOGICAL SCENE
MONTHLY SUMMARY
No. 668 For AUGUST 2011
A VERY WARM START, OTHERWISE ANOTHER COOL AND UNSETTLED MONTH
Text Box: The month began with a tropical air-mass in occupation over central and eastern districts, but from the 4th until the 29th a mainly cyclonic type held sway with only brief interruptions, though high pressure returned during the last few days. Mean monthly sea-level pressure was 2.5-4.0 mbar below normal over the entire British Isles, and the anomalous flow was northeasterly over the northern half of the UK and northwesterly over the southern half.

Eastern and central England were very warm and humid with sunny periods during the first three days with highs of 25-29C, and 30.3C at Swanscombe (Kent) on the 3rd, while the highest overnight low was 17.9C at Eastbourne (Sussex), also on the 3rd. But there were also scattered showers and local thunderstorms, notably on the 3rd in the East Midlands and Yorkshire where 50mm fell at Howden (East Riding). The warmth was much less prominent in northern and western regions and here it was mainly cloudy with outbreaks of rain. A belt of rain spread northeastwards across the whole country on the 4th which was generally cooler and rather breezy, but the next day was mostly dry, except in Lancs and Yorks, with sunny spells and it was warm again in the Southeast.

A secondary depression headed quickly NNE-wards on the 6th and became slow-moving near NE Scotland; heavy rain affected Scotland and northern England with a 2-day total of 66mm at Lentran House (just west of Inverness). Heavy showers and local thunderstorms affected England and Wales on the 7th, but there were fewer showers on the 8th which was a rather cool day. The 9th was quite sunny over England and Wales, but heavy rain spread across northern and western parts of the UK overnight 9th/10th and continued into the 11th in southern Scotland and northern England. In 48h 77mm fell at Salsburgh (Lanarks), 76mm at Preston and 74mm at Stonyhurst (both Lancs). Further Atlantic depressions brought more rain on the 12th/13th and 15th/16th, mainly to northern and western parts though Lerwick (Shetland) enjoyed 14.4h bright sunshine on the 15th.
Text Box: On the 18th it was the turn of southern Britain to be wet, with widespread heavy rain south of a line from Swansea to Lincoln; 66mm fell at Stratfield Mortimer (Berks) and afternoon highs were widely around 12-14C in the wet zone. The next few days were rather warm in eastern England with occasional sunshine, but there were showers too, especially in the north and west, though the 21st and 22nd were largely dry. At Katesbridge (Co Down) the temperature fell to 1.1C early on both the 19th and 23rd.

The 23rd was a cool, dull day in eastern and southern England with occasional rain but the rest of the UK was mostly dry. Between the 24th and 27th a complex depression drifted northeastwards across the country bringing frequent showers, some thunderstorms, and there were longer periods of heavy rain at times; northern Scotland was particularly wet and windy on the 27th/28th and 92mm fell at Elphin (Sutherland) over 48h. At Loch Glascarnoch (Wester Ross) the day's maximum on the 28th was just 8.0C while Wick registered a peak gust of 58kn. The closing days of the month were cool, cloudy and largely dry, though there was a little rain here and there.

Mean maximum temperature ranged from 0.0-0.5 degC below the 1981-2010 average in the Southeast, East Anglia and the Midlands, to 1.5-2.0 below in parts of Scotland. The mean minimum was 0.5-1.0 degC below in most regions. As measured by the CET it was the coolest August only since last year, though there has been none other cooler since 1993. Rainfall percentages ranged from around 50 in parts of the Midlands and northern Ireland to approaching 300 locally in northern and eastern Scotland and northeast England. Monthly rainfall totals varied between 219mm at Cluanie Inn (Wester Ross) and 19mm at Newport (Shropshire). Sunshine percentages ranged from 95 in Shetland to 50-60 in southern Scotland and the central Belt, while sunshine aggregates varied between 211 hours at Thorney Island (West Sussex) and 54 hours at Kinlochewe (Wester Ross).
                                                                                                                                             
    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   20.5   -0.6   12.6   -0.2   28.3   03   08.6   19   00   00   03   09.6   01   136   071   1910   282   1995   097   2008   10   16.7   18   086   140   1910   184   1975   02   1995   00   00   00  
  Thorney Island   20.2   -1.6   13.3   -0.1   24.9   03   08.4   19   00   00   01   11.4   01   211   091   1958   303   1976   117   2008   17   16.2   24   064   140   1941   141   1960   04   1976   01   00   00  
  *Wattisham   20.8   -0.2   11.8   +0.2   28.6   03   06.5   19   00   00   03   13.1   01   151   079   1968   285   1995   122   2008   14   14.8   18   071   154   1960   147   2010   03   2003   01   00   00  
  *Wittering   20.6   +0.2   11.7   -0.3   27.7   02   07.8   15   00   00   03   10.8   09   122   065   1950   258   1995   090   1971   16   09.6   18   045   083   1948   162   2004   03   1983   02   00   00  
                                                                     
  *Lyneham   19.5   -0.9   11.6   -0.3   25.9   01   05.7   19   00   00   03   10.2   02   135   067   1952   297   1995   111   2008   11   26.8   26   082   144   1945   136   1951   02   1995   01   00   00  
  Ross-on-Wye   21.1   +0.2   11.7   -0.5   25.5   03   06.0   15   00   00   00   11.3   03   149   083   1915   307   1995   107   1922   17   06.0   25   023   042   1859   202   1878   04   1936   00   00   00  
  *St Athan   18.6   -1.5   12.8   +0.3   21.9   03   07.3   19   00   00   01   11.3   22   134   064   1954   325   1995   089   2008   10   13.2   03   088   120   1954   202   1997   22   1955   00   00   00  
  Culdrose   17.8   -1.1   12.3   -0.8   19.7   20   07.0   30   00   00   01   11.8   09   157   073   1961   312   1976   105   2008   15   21.2   03   058   098   1961   208   1997   04   1981   00   00   00  
                                                                     
  *Edgbaston   19.8   -1.0   12.4   -0.4   26.9   03   09.9   19   00   00   00   09.5   03   159   085   1887   282   1995   085   1896   18   15.0   24   035   075   1887   173   1912   06   1940   01   00   00  
  *Valley   17.6   -1.3   12.4   -0.4   19.9   23   08.8   31   00   00   02   10.9   17   139   068   1946   291   1976   086   2008   14   23.8   10   068   116   1941   210   1956   05   1959   01   00   00  
  *Woodford   19.0   -0.8   10.9   -0.4   25.2   03   04.9   18   00   00   04   10.2   25   097   056   1945   284   1995   079   2008   09   13.0   10   056   081   1942   201   1956   07   1976   03   00   00  
  *Watnall   20.2   -0.2   11.8   -0.2   27.3   03   07.8   18   00   00   03   09.9   09   117   062   1948   261   1995   098   1963   17   13.4   24   038   069   1942   154   2004   04   1995   02   00   00  
                                                                     
  *Leeming   19.4   -0.7   10.4   -1.0   25.8   03   05.0   17   01   00   04   10.4   05   131   076   1945   246   1995   086   2008   12   13.6   06   086   113   1945   165   1971   07   1947   03   00   00  
  *Boulmer   17.5   -0.4   11.1   -0.4   21.3   05   07.6   25   00   00   03   09.5   20   117   070   1945   273   1995   072   2008   10   26.6   06   091   136   1945   199   1956   03   1947   01   00   00  
  *Eskdalemuir   16.2   -1.5   08.9   -0.4   20.3   03   03.2   15   00   00   06   10.3   09   072   048   1911   260   1947   041   2008   03   16.8   12   151   148   1911   393   2009   01   1947   01   00   01  
  *Bishopton   17.6   -1.5   10.2   -0.5   22.3   03   05.7   25   00   00   09   11.3   20   097   060   1921   254   1995   068   2008   08   23.7   09   131   187   1921   213   2004   00   1947   01   00   00  
                                                                     
  *Leuchars   17.3   -1.2   10.2   -0.5   21.3   05   06.8   31   00   00   06   10.9   03   113   065   1922   242   1995   095   2008   10   51.0   10   154   267   1922   213   2004   07   1955   01   00   00  
  *Dyce   16.4   -1.5   10.2   +0.1   20.7   21   03.8   12   01   00   05   09.5   20   095   059   1941   257   1947   076   1963   12   22.6   10   125   186   1941   162   1962   00   1947   00   00   00  
  *Stornoway   15.6   -0.5   10.0   -0.1   18.0   23   05.4   19   01   00   04   11.8   25   101   066   1880   262   1899   065   2006   07   09.0   10   078   124   1943   203   1982   13   1947   00   00   00  
  *Aldergrove   17.4   -1.1   11.0   -0.1   21.5   04   06.5   19   00   00   03   08.1   03   093   062   1927   276   1976   061   2008   11   11.4   09   038   058   1927   181   2008   09   1947   01   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.