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graphs CLIMATE-UK.COM'S REVIEW OF THE BRITISH METEOROLOGICAL SCENE
MONTHLY SUMMARY
No. 633 For SEPTEMBER 2008
EXCEPTIONALLY WET FIRST WEEK, BUT MAINLY DRY SECOND HALF; A DULL MONTH ACROSS THE MIDDLE OF THE COUNTRY
Text Box: The first week was markedly cyclonic, the second week more weakly so, and the second half of the month was mostly anticyclonic. Sea-level pressure was well below normal over Iceland and Greenland, but well above over Scandinavia and the Baltic, but anomalies were small over Europe and the Atlantic south of the 57th parallel. The anomalous flow over the British Isles was weakly southeasterly.

Pressure was low over the British Isles throughout the first week, and between the 5th and 7th a deep depression tracked slowly ENE-wards across England. A weak ridge crossed the country on the 8th but over the next few days a large anticyclone developed over Scandinavia and subsequent Atlantic depressions were steered northwards close to western Ireland and northwest Scotland.

The first four days of September were unsettled, cool, and rather windy with widespread showers, heavy at times and accompanied locally by hail and thunder, but there were also some sunny intervals. A gust of 57kn was recorded on Mumbles (Glamorgan) on the 3rd.  Early on the 5th, under clear skies and with little or no wind, the temperature dropped to -1.7C at Braemar (Aberdeenshire). The same day prolonged heavy rain spread from the southwest, and during the next 48 hours upwards of 50mm fell over large parts of southwest England, Wales, the Midlands, northeast England and the Scottish Borders. Flooding was severe in south Wales where 185mm fell in 24 hours at Pontsticill reservoir (above Merthyr Tydfil), and in Northumberland (notably in Morpeth) where 101mm fell in 48 hours at Albemarle, near Ponteland. Northern and western Scotland escaped the worst of the weather, and Tiree (Inner Hebrides) logged 55h of bright sunshine between the 3rd and 7th inclusive. The next few days were mostly cloudy with further rain at times, and although amounts of rain were much smaller, there was a thunderstorm-related fall of 43mm at Larkhill (Wilts) on the 12th. It was briefly warm on the 11th in Kent and East Anglia, and the months highest reading of 23.7C was recorded at Buxton (Norfolk) on this day.
Text Box: The Scandinavian anticyclone extended its influence across the UK from the 13th onwards although for several days an old frontal zone was slow-moving over Scotland and Ireland. A new anticyclone from the Atlantic became the dominant feature from the 22nd until the 27th (up to 1038.3 mbaat Fylingdales, N.Yorks, on the 26th), followed by a steady fall of pressure and a steepening westerly gradient as the month drew to a close.

Most parts of England and Wales were dry and cloudy between the 13th and 18th, but there was further rain at times in Scotland and Northern Ireland, and occasionally also in northwest England and Wales. Large parts of the UK became fine and pleasantly warm from the 19th till the 21st with long sunny periods and highs of 18-21C. A cool and cloudy northeasterly flow affected England and Wales between the 22nd and 25th but skies cleared in Scotland and the temperature at Tulloch Bridge (Lochaber) fell to -2.1C early on the 22nd and to -1.6C on the 23rd. The 26th-28th were sunny and rather warm after the clearance of morning fog patches. All districts were windy with outbreaks of rain on the 30th and the days high at Dalwhinnie (Inverness-shire) was just 9.2C.

Mean temperature was within 0.5degC of the 1971-2000 norm over much of the UK, but was 1.0-1.5degC above at several sites in the north and northwest of Scotland. A notable feature of the month was the complete absence of very warm days; several locations even in southern England failed to reach 20C. Many places exceeded their normal rainfall for the entire month during the first week, but very little rain fell in England and Wales after the 12th, and in Scotland and Northern Ireland after the 18th. Northern Scotland, which escaped the downpour on the 5th-6th, ended up with a very dry month. Sunshine totals were generally 10-20 per cent below normal, but 30-50 per cent below in southwest Scotland. Over England and Wales it was the coolest and cloudiest September since 2001 and the wettest since 2000.
                                                                                                                                             
    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   17.6   -0.6   10.8   +0.4   20.3   19   08.0   29   00   00   03   08.7   14   108   082   1910   224   1959   072   1945   14   19.8   05   057   094   1910   157   1918   02   1959   00   00   00  
  Thorney Island   17.9   -1.3   10.7   -0.3   19.5   01   06.3   28   01   00   03   11.7   20   140   090   1958   245   1959   129   1967   13   16.6   05   066   124   1941   159   1974   02   1971   00   00   00  
  *Wattisham   17.4   -0.7   09.8   +0.3   21.6   11   05.4   27   00   00   02   11.0   20   115   081   1968   232   2003   103   1984   09   07.8   07   046   100   1960   119   1968   01   1969   00   00   00  
  *Wittering   17.3   -0.4   10.2   +0.5   20.5   10   05.1   27   00   00   03   10.2   21   111   081   1950   207   1964   093   1967   10   13.8   05   050   106   1948   132   1992   02   1959   00   00   00  
                                                                     
  Lyneham   17.0   -0.5   09.7   +0.1   19.7   20   06.4   28   00   00   01   10.3   21   120   084   1952   235   1959   100   1983   15   15.9   05   098   151   1945   142   1974   05   1959   00   00   00  
  Ross-on-Wye   17.7   -0.2   09.7   0.0   21.1   19   03.9   27   00   00   05   08.8   13   092   072   1914   205   1929   069   1945   11   29.2   05   111   173   1859   203   1976   02   1865   00   00   00  
  *St Athan   17.3   -0.1   11.0   +0.3   20.1   10   07.5   28   00   00   04   10.4   18   130   090   1954   249   1959   074   1956   13   35.6   01   173   192   1954   223   1974   14   1959   00   00   00  
  St Mawgan   16.8   -0.3   11.3   -0.1   19.1   10   09.2   22   00   00   01   10.8   20   178   114   1945   258   1959   080   1956   16   18.6   04   063   078   1944   179   1974   10   1959   00   00   00  
                                                                     
  *Edgbaston   16.7   -0.1   10.6   +0.4   20.1   20   08.0   26   00   00   02   09.4   21   092   075   1887   216   1895   067   1909   13   17.0   05   102   153   1887   165   1918   04   1959   00   00   00  
  *Valley   16.2   -0.6   11.6   +0.4   19.3   14   07.6   23   00   00   04   11.1   23   125   089   1946   214   1949   096   1948   15   25.8   05   107   129   1941   174   1950   03   1986   00   00   00  
  *Woodford   17.0   +0.2   09.2   0.0   19.7   20   04.8   29   01   00   07   10.9   20   098   082   1945   197   1959   069   1948   11   31.0   05   082   110   1942   171   1965   05   1959   01   00   00  
  *Watnall   17.2   -0.5   10.3   +0.6   20.4   20   07.4   29   04   00   04   10.4   21   097   070   1948   177   1991   075   1993   15   27.6   05   101   215   1942   147   1957   02   1959   00   00   00  
                                                                     
  *Leeming   17.1   -1.0   09.8   +0.6   20.8   20   03.7   29   00   00   07   10.0   27   090   075   1945   200   1986   073   1976   12   41.4   05   115   234   1945   174   1976   04   1959   00   00   00  
  *Boulmer   16.1   -0.2   10.0   +0.7   20.6   20   05.6   05   00   00   04   08.3   01   079   063   1945   205   1986   075   2001   13   31.4   06   098   179   1945   147   1965   12   2004   00   00   00  
  *Eskdalemuir   14.4   -0.5   07.7   +0.6   17.7   14   00.7   28   03   00   09   06.1   01   * 046   047   1911   153   1959   055   1980   06   22.0   05   121   085   1911   308   1950   18   1972   00   00   00  
  *Bishopton   15.7   -0.6   09.4   +0.7   19.4   21   03.8   28   01   00   06   07.3   22   * 058   052   1921   169   1996   068   1965   09   27.4   15   114   120   1921   258   1985   11   1972   00   00   00  
                                                                     
  *Leuchars   16.1   -0.1   09.4   +0.7   19.5   21   04.5   28   04   00   04   10.4   22   094   074   1922   181   1997   077   1956   12   10.4   15   046   090   1922   149   1950   05   1972   00   00   00  
  *Dyce   15.9   +0.4   09.1   +1.1   20.5   20   04.9   17   00   00   05   08.8   17   083   072   1941   181   2004   070   1968   15   12.8   09   042   065   1941   234   1995   15   1959   00   00   00  
  *Stornoway   14.6   +0.4   09.3   +0.6   17.2   09   05.0   22   01   00   05   11.2   05   074   070   1880   175   1903   070   1965   10   13.6   29   057   055   1943   206   1981   34   1968   00   00   00  
  *Aldergrove   16.1   0.0   09.7   +0.3   19.1   20   03.5   23   03   00   02   11.3   22   089   083   1927   177   1986   070   1962   14   16.2   14   074   093   1927   163   1981   06   1986   00   00   00  
                                                                     
                                                                                                                                             
  Stations marked with an asterisk record sunshine electronically; comparisons      
  with earlier records are therefore somewhat speculative. Thorney Island's   * New low record    
  sunshine figures are made at a nearby site.