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graphs CLIMATE-UK.COM'S REVIEW OF THE BRITISH METEOROLOGICAL SCENE
MONTHLY SUMMARY
No. 667 For JULY 2011
VERY DRY IN NORTHERN AND WESTERN SCOTLAND, OTHERWISE MOSTLY COOL AND CHANGEABLE
Text Box: Short anticyclonic spells occurred on the 1st-4th, 11th-15th, and 27th-30th, but cyclonic conditions prevailed for most of the rest of the month. Mean sea-level pressure for July ranged from fractionally above normal in the far north of Scotland to 3-4 mbar below over much of England, and it was among the top five per cent of most 'northeasterly' Julys in the last 139 years.

With rising pressure in a polar air-mass, the early morning of the 1st was decidedly cold with a widespread slight ground frost and an air minimum of 0.9C at Kinbrace (Sutherland); the afternoon was rather cool in spite of abundant sunshine and light winds. The weather became progressively warmer over the next three days and there were long sunny periods, with 16.3h bright sunshine at Morecambe (Lancs) on the 3rd - the month's highest daily duration. The warm spell peaked on the 5th with a high of 27.3C at Swanscombe (Kent), but by then the warmth was confined to central and eastern England and rain was already spreading across western and northern regions of the UK. The deep depression responsible for the change was centred west of Ireland on the 5th and it drifted very slowly east then northeast across the British Isles, reaching the North Sea on the 9th/10th. During this period rain fell widely and sometimes heavily, especially in Scotland and northern England, and there were frequent showers, some of them thundery, further south. The 8th in particular was quite windy. 

High pressure developed near Iceland during the 10th/11th, subsequently sinking slowly southwards over the next five days to reach Biscay on the 15th.  There were further heavy showers in eastern England on the 10th, otherwise these few days were generally dry with variable amounts of cloud and occasional sunshine, but the Channel Islands were particularly wet on the 12th as an upper-air disturbance passed over and there was further occasional rain towards the east coast on the 12th-14th. Where the cloud broke it became rather warm by day but it was notably cold at night, and early on the 13th Kinbrace (Sutherland) recorded an air minimum of -0.8C.
Text Box: An unusually deep depression for the season tracked SE-wards across Scotland between the 16th and 19th, thence turning northwards and filling, allowing a northerly flow to develop across the UK. A further shallow disturbance tracked from Ireland to northern France on the 20th/21st. This was the coolest and cloudiest part of July, and there were heavy falls of rain in most parts of the country especially between the 15th and 18th. On the 15th 53mm fell at Spadeadam Forest (Cumbria), and on the 16th 96mm at Capel Curig (Caernarfon) and 50mm at Thorncliffe (Staffs). Afternoon temperatures were occasionally below 15C in Scotland, and below 18C even in southern England, and on a day of thick cloud and periods of rain, the temperature reached only 10.8C on the 18th at Okehampton (Devon). 

Western areas became dry and sunny between the 20th and 25th but showers continued to affect central and especially eastern districts. A build of pressure across the British Isles settled the weather down between the 26th and 29th, and most places were generally dry, but sunshine was variable rather than plentiful, and daytime temperatures rose only a few degrees above normal. The last two days of July were fine and warm with 26.8C reached at Sutton Bonington (Notts) on the 31st.

Mean maximum temperature was 0.5-1.5 degC below the 1981-2010 average and the mean minimum was 1.0-2.0 degC below in most regions, and as measured by the CET it was the coolest July for four years. Locally in southern England it was the coolest since 1988. Rainfall percentages ranged from below 60 in parts of northern and western Scotland where Kirkwall (Orkney) registered just 18mm, to over 150 in southeast Scotland and northeast England and over 250 on Jersey, but rainfall was also below average in Northern Ireland and parts of the English Midlands. Sunshine percentages varied between 50 in Shetland and 120 in some western coastal districts; the total at Lerwick (Shetland) of 64h contrasted with 256h at St Athan (Glamorgan).
                                                                                                                                               
    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   -0.9   11.6   -1.3   24.9   05   09.0   01   00   00   00   11.2   30   161   087   1910   321   1911   109   1913   16   14.1   18     060   128   1910   193   1924   05   1921   00   00   00  
  *Thorney Island   19.8   -2.3   12.1   -1.1   23.7   25   08.4   19   00   00   00   12.6   04   233   098   1958   336   2006   153   1978   18   13.6   07     054   127   1941   122   1945   06   1949   00   00   00  
  *Wattisham   19.7   -1.3   11.0   -0.7   23.6   05   07.8   15   00   00   03   14.5   04   153   081   1968   295   1976   131   1978   16   13.0   17     059   136   1960   101   1987   05   1977   02   00   00  
  *Wittering   20.5   +0.1   10.9   -1.1   25.0   05   06.8   30   00   00   01   11.0   01   137   072   1955   283   2006   115   1965   17   16.2   19     056   124   1955   153   2004   06   1977   02   00   00  
                                                                       
  *Lyneham   20.0   -0.9   11.1   -1.0   24.5   04   06.9   01   00   00   02   11.8   14   139   065   1952   314   2006   129   1965   18   16.6   08     062   143   1945   149   2007   04   1955   01   00   00  
  Ross-on-Wye   21.2   +0.1   11.2   -1.2   24.8   04   05.8   25   00   00   00   11.9   24   181   097   1915   311   2006   095   1944   19   06.0   05     037   084   1859   197   1872   06   1935   00   00   00  
  *St Athan   19.2   -0.9   12.4   -0.1   22.8   04   07.3   01   00   00   03   14.4   03   256   120   1954   319   1955   131   1965   13   13.6   21     076   128   1954   188   2009   13   1977   00   00   00  
  Culdrose   18.1   -0.6   12.2   -0.6   21.4   26   07.7   03   00   00   03   15.1   14   200   090   1961   306   1971   117   1991   17   07.8   04     039   078   1961   197   2009   05   1999   00   00   00  
                                                                       
  *Edgbaston   20.4   -0.9   11.9   -1.0   25.1   04   08.6   23   00   00   00   13.6   24   189   105   1887   285   1990   067   1888   19   09.4   15     037   094   1887   183   2007   07   1911   01   00   00  
  *Valley   18.2   -0.5   11.4   -1.1   23.0   27   07.1   14   00   00   00   15.5   03   233   116   1946   341   1955   115   1986   18   16.4   06     049   103   1941   127   2010   09   1983   00   00   00  
  *Woodford   19.7   -0.1   09.9   -1.4   25.1   04   03.7   14   02   00   02   15.1   03   164   097   1945   280   2006   082   2010   17   28.2   17     079   123   1942   187   1973   10   1999   01   00   00  
  *Watnall   20.4   -0.1   11.1   -0.9   24.5   31   08.1   23   00   00   01   12.9   24   148   078   1948   273   2006   087   1965   21   07.4   16     033   074   1942   148   1973   11   1982   02   00   00  
                                                                       
  *Leeming   20.0   -0.3   09.7   -2.0   24.8   04   05.2   14   01   00   00   14.3   24   153   092   1945   276   2006   091   1965   21   11.4   16     036   086   1947   139   2009   09   1984   01   00   00  
  *Boulmer   16.6   -1.5   10.9   -0.9   20.0   10   08.3   14   00   00   04   15.7   03   192   107   1945   268   1955   105   1957   16   18.4   06     080   166   1945   155   2009   07   2006   00   00   00  
  *Eskdalemuir   18.2   +0.3   07.4   -1.8   22.4   04   01.4   01   02   00   02   14.9   24   161   106   1911   266   1989   069   2010   16   37.4   15     135   152   1911   269   1988   25   1913   01   00   00  
  *Bishopton   20.2   +1.0   09.9   -0.9   23.5   26   06.0   03   00   00   02   15.8   24   225   130   1921   297   1989   086   1931   15   18.2   05     097   169   1921   155   2010   11   1984   01   00   00  
                                                                       
  *Leuchars   17.9   -0.9   10.2   -0.6   22.4   03   05.5   13   02   00   01   16.1   03   169   088   1922   262   1955   091   1931   16   27.4   05     105   195   1922   181   1940   13   1983   01   00   00  
  *Dyce   16.3   -1.8   10.4   +0.3   19.9   03   03.2   13   01   00   05   15.2   13   122   074   1941   263   1955   078   1968   18   16.4   10     076   124   1941   198   1957   13   2003   00   00   00  
  *Stornoway   15.9   +0.1   10.5   +0.2   20.3   27   06.3   13   00   00   03   11.1   13   122   089   1880   227   1917   057   1939   16   11.2   17     045   075   1943   165   1988   14   1955   00   00   00  
  *Aldergrove   18.4   -0.2   10.4   -0.8   23.8   27   06.2   23   00   00   05   14.7   23   159   111   1927   274   1955   080   2010   13   11.6   17     075   097   1927   155   1950   12   2000   00   00   00  
                                                                       
                                                                                                                                               
  Stations marked with an asterisk record sunshine electronically; comparisons      
  with earlier records are therefore somewhat speculative.      
  Averages for 1971-2000 are still in use in the table; those for 1981-2010 will be      
  introduced in January 2012.