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graphs CLIMATE-UK.COM'S REVIEW OF THE BRITISH METEOROLOGICAL SCENE
MONTHLY SUMMARY
No. 672 For DECEMBER 2011
A 'WESTERLY' MONTH; FREQUENT GALES AND HEAVY RAIN IN THE WEST AND NORTH
Text Box: Winds from a westerly quarter blew almost without a break throughout December; over the British Isles it was the second most 'westerly' December, after 1974, in 139 years of records. As a consequence there were several extended periods of orographically-enhanced rainfall in the western highlands of Scotland, the Lake District and Snowdonia. There were also frequent gales in the northern half of the country.

During the first 15 days of the month a series of deep depressions tracked NE-wards between Scotland and Iceland. Throughout this period the weather was very unsettled in all parts of the country, it was often windy, many places had rain daily, and there were sharp fluctuations in temperature and highest readings were occasionally obtained at night. Maxima exceeded 13C locally in southern England on each of the first four days, the 8th and the 12th, but the 5th and 6th were colder with highs of 4-7C in southern districts, and locally below 0C in the Scottish highlands. Snow lay 15cm deep on both these days at Eskdalemuir (Dumfriesshire) and was also noted near sea-level in northern Scotland, while overnight temperature fell to -8.0C at Cromdale (Morayshire) early on the 10th. Gales swept northern districts almost daily, but the gale of the 8th was particularly severe with gusts to 85kn at Foula (Shetland), 80kn at Fair Isle, and 79kn at Tiree (Inner Hebrides). Rain was heaviest on west-facing slopes: 57mm was logged on the rainfall day of the 9th at Loch Glascarnoch (Wester Ross) and again 57mm at Tyndrum (Stirlingshire) on the 13th. The month's highest daily sunshine duration was 6.9h at Norwich on the 9th.

A deep depression tracked ENE-wards along the English Channel overnight 15th/16th bringing upwards of 12h of steady rain to southern and some central parts of England and Wales. The rain turned readily to sleet and eventually to snow chiefly over the Welsh hills and the hills of the south Midlands. Some 6cm lay at Whipsnade (Beds).
Text Box: In the following cold northwesterly airstream which lasted until the 19th, snow showers affected many parts of the country with accumulations 5-10cm locally in northeast Scotland, north Wales, and the Peak District. The temperature climbed no higher than -3.0C at Aviemore (Inverness-shire) on the 16th, and fell to -9.4C at Loch Glascarnoch early on the 18th.

Much milder southwesterly winds prevailed for most of the last  ten days of December, though there were incursions of polar air on the 23rd/24th and 29th/30th. The temperature reached 14.4C at Rhyl/Bodelwyddan (Denbighshire) on the 21st and 14.1C at Rosehearty (Aberdeenshire) on the 22nd, but climbed even higher over the Christmas holiday with 15.1C at Dyce (Aberdeenshire) on the 25th and 15.5C at Fyvie (also Aberdeenshire) on the 26th; the highest overnight minimum was 12.7C at Murlough (Co Down) on 25th/26th. A severe gale swept northern Scotland on the 25th, with gusts to 84kn at Foula and 79kn at Lerwick (both Shetland) while 118mm of rain fell in the 48h to 09z on the 27th at Kinlochewe (Wester Ross). A further 59mm fell at Cluanie Inn (Wester Ross) on the 28th, but it became very mild again on the 31st with 14.1C at Credenhill (Herefs).

Monthly mean temperature ranged from 0.5 degC below normal in Northern Ireland to 1.5-2.0 degC above in southern England and south Wales, and as measured by the CET it was the warmest December for five years. Rainfall percentages ranged from over 200 locally in western Scotland to 50-60 at scattered locations in eastern Scotland and eastern England. The highest total to hand was 595mm at Cluanie Inn (Wester Ross). Sunshine totals were well below normal in most western districts, but up to 40 per cent above locally in eastern England; totals ranged from 13 hours at Lerwick (Shetland) to 80 hours at Wattisham (Suffolk).
                                                                                                                                             
    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   08.1   +0.4   03.7   +1.3   12.1   22   -02.4   19   16   05   03   06.0   22   064   144   1910   086   2001   008   1956   08   15.4   12   068   103   1910   175   1914   10   1933   00   01   00  
  *Thorney Island   09.8   +1.2   05.2   +1.5   13.3   21   -01.7   19   09   03   01   05.9   09   078   134   1958   114   2001   037   1966   10   22.8   12   101   131   1941   165   1993   19   1953   00   00   00  
  *Wattisham   07.6   +1.1   02.8   0.0   12.6   26   -05.2   19   12   07   06   06.7   22   080   160   1979   082   2008   022   2002   07   08.8   12   065   117   1964   120   1965   20   2010   00   03   00  
  *Wittering   08.0   +1.5   03.4   +0.8   13.2   26   -03.4   18   11   04   09   05.6   03   060   120   1950   082   2001   020   1956   14   09.4   11   047   082   1948   130   1978   07   1963   00   04   00  
                                                                     
  *Lyneham   08.2   +1.0   04.0   +1.2   12.1   21   -01.0   18   15   04   11   06.0   03   063   126   1952   083   2001   017   1956   11   19.0   12   071   091   1945   159   1959   13   2010   00   03   00  
  Ross-on-Wye   08.1   +0.7   04.8   +1.4   13.3   08   -01.1   17   12   04   00   06.8   07   069   142   1915   078   1948   012   1989   01   16.6   12   066   087   1859   197   1929   11   1991   00   02   00  
  *St Athan   09.5   +1.5   05.8   +1.7   12.8   08   -01.8   10   04   01   12   05.5   07   035   076   1954   072   2008   003   1956   03   13.4   30   148   148   1954   208   1965   28   2010   00   00   00  
  *Culdrose   10.2   +0.6   07.0   +0.9   12.6   03   02.0   10   04   01   12   05.5   17   029   057   1961   088   2009   021   1988   07   11.6   02   079   066   1961   246   1978   27   1975   00   00   00  
                                                                     
  *Edgbaston   07.9   +0.5   04.2   +0.9   12.4   08   00.2   19   13   00   01   04.2   03   067   153   1887   090   1891   005   1890   10   07.2   23   051   066   1887   166   1965   10   1926   00   03   00  
  *Valley   09.2   +0.3   06.3   +0.9   12.1   08   01.7   16   03   00   13   03.2   28   * 021   043   1946   080   1960   025   1998   06   11.6   12   089   091   1941   179   1964   17   1963   00   02   00  
  *Woodford   07.6   +0.8   03.3   +1.0   12.9   26   -05.0   18   14   06   14   05.0   18   030   067   1945   075   2001   016   1947   02   23.4   05   173   205   1942   180   1965   11   1963   00   05   00  
  *Watnall   07.8   +1.3   03.6   +1.0   13.2   26   -02.0   18   11   04   06   05.2   03   060   120   1948   078   2009   012   1956   13   13.2   12   072   125   1941   180   1965   19   1963   00   06   00  
                                                                     
  *Leeming   07.6   +0.6   02.8   +0.5   12.9   26   -04.6   19   16   07   07   05.7   18   044   106   1945   077   1967   014   1972   09   10.8   12   061   095   1945   125   1978   16   1988   00   05   00  
  *Boulmer   07.2   +0.3   03.1   +0.7   13.5   26   -02.2   16   11   04   08   05.9   18   056   125   1945   082   2006   021   2002   10   09.2   30   056   087   1945   205   1978   17   1975   00   04   00  
  *Eskdalemuir   05.2   -0.2   01.2   +0.4   12.5   25   -05.0   17   18   10   20   05.7   18   017   045   1911   074   1967   003   1912   00   28.4   07   267   157   1911   351   1993   33   1933   00   13   02  
  *Bishopton   06.6   -0.6   02.5   +0.3   12.8   25   -02.7   17   13   06   10   05.5   15   031   099   1921   072   2001   009   1956   00   25.8   13   250   220   1921   295   2006   15   1933   00   09   00  
                                                                     
  *Leuchars   06.5   -0.2   01.5   -0.6   13.9   25   -04.8   16   25   10   08   05.3   07   055   109   1921   082   1967   016   1934   10   08.6   30   051   076   1921   155   1978   08   1926   00   08   00  
  *Dyce   06.6   +0.2   01.6   +0.1   15.1   25   -05.8   16   18   08   03   05.5   04   057   127   1941   088   2006   016   2002   14   08.2   08   051   060   1941   160   1978   20   1991   00   10   00  
  *Stornoway   07.0   -0.5   02.5   0.0   12.5   25   -03.0   05   12   06   14   03.0   15   016   062   1880   057   1995   006   1884   00   15.8   07   195   147   1943   222   1985   29   1977   00   07   00  
  *Aldergrove   07.2   +0.1   03.4   +0.5   12.5   25   -01.0   15   11   02   08   04.7   07   034   099   1927   078   2010   017   1954   02   07.8   04   087   091   1927   195   1978   15   1963   00   06   00  
                                                                     
                                                                                                                                             
  Stations marked with an asterisk record sunshine electronically; comparisons      
  with earlier records are therefore somewhat speculative. Thorney Island's   * New lowest    
  sunshine figures are made at a nearby site.