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graphs CLIMATE-UK.COM'S REVIEW OF THE BRITISH METEOROLOGICAL SCENE
MONTHLY SUMMARY
No. 612 For DECEMBER 2006
WET AND VERY MILD FIRST HALF; COLD AND FOGGY FOR A TIME DURING SECOND HALF
Text Box: December was dominated by southwesterly winds - only the Decembers of 1974 and 1912 were significantly more southwesterly - but there was a marked contrast between the strongly cyclonic first half of the month and the very anticyclonic second half, although the cyclonic bias returned from the 29th onwards. The main anomaly centres were -15mbar over eastern Greenland and +11mbar over the Balkans.

The month opened with a deep depression centred over Iceland, high pressure over eastern Europe, and a broad southwesterly flow over the British Isles. Between the 2nd and 4th a very deep and complex depression tracked slowly past northwest Scotland, and further less deep disturbances followed a similar track on the 5th and the 7th. This was the warmest and most disturbed phase of the month. Rain fell daily, and there were some exceptional totals in upland areas including 163mm in 48h on the 2nd/3rd at Sloy (Argyll) and 88mm at Capel Curig (Snowdonia) on the 4th; many rivers in central Scotland overtopped their banks. Temperatures reached 13 or 14C widely, with 15C recorded at several sites in the West Country and the Channel Islands on the 4th and 5th, while the minimum recorded at Weybourne (Norfolk) on the intervening night was an exceptional 13.6C. It was also a very windy spell with gusts of 60-70kn at exposed sites on most days, and on the 3rd gusts of 85kn at Mumbles (Glamorgan) and 77kn at Plymouth (Devon) were logged. A short-lived tornado caused structural damage in Kensal Rise (London) on the 7th.

The next depression travelled across Iceland between the 9th and 11th, deepening to 930mbar for a time, but pressure now rose across France and Germany. A broad tropical maritime flow covered the country from the 13th till the 15th as further depressions tracked between Scotland and Iceland. There was further heavy rain almost daily in northern and western Britain, with 180mm at Honister Pass (Cumbria) on the 10th and 87mm at Capel Curig on the 14th, and flooding hit parts of Cumbria. Temperatures of 12-13C were recorded widely.
Text Box: A quieter and somewhat cooler phase followed on the 16th and 17th although the flow was still mainly westerly, but rain returned on the 18th as a small depression moved southeastwards across the British Isles. In its wake pressure rose strongly, and from the 19th to the 27th a large anticyclone lay over or close to the UK. Sea-level pressure climbed to 1046.3mbar at Sennybridge (Breconshire) on the 21st, the highest in England and Wales since January 1992. Persistent fog affected large areas of England from the 19th-22nd inclusive resulting in severe disruption to air traffic, but some areas were exceptionally sunny: Portland (Dorset) logged 7.6h of bright sunshine on the 20th and St Mawgan (Cornwall) 7.5h on the 21st, while the Aberdeen district enjoyed prolonged sunshine on 11 of the 12 days from the 16th to the 27th. Sharp frosts occurred nightly with minima typically between -3 and -7C, and on the morning of the 25th -9.4C was recorded at Aboyne (Aberdeenshire). Daytime temperatures remained below freezing in some places, not only where fog persisted: there were three consecutive sub-zero days in the Vale of York from the 19th-21st, and in parts of Aberdeenshire from the 25th-27th. The lowest maximum was -2.6C at Redesdale (Northumberland) on the 24th.

A vigorous southwesterly airflow returned during the last three days of the month, bringing heavy rain, locally thunder, and rough winds. A gust of 76kn was recorded at Landon Bay early on the 30th, while local wind damage later that day in Berkshire and Suffolk may have been tornado-related. 

In spite of the frosty spell over Christmas, this was the warmest December (as measured by the CET) since 1988. Averaged nationally, rainfall and sunshine were both slightly above normal; however there were huge contrasts across Scotland where Glasgow had its wettest December on record while Aberdeen had its driest since 1991. Also, Aberdeens sunshine total of 88 hours smashed the previous record of 67 hours which was established in 1951. A new December sunshine record was also set at Boulmer (Northumberland).
                                                                                                                                             
    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   09.0   +1.3   03.9   +1.5   13.5   04   -02.9   22   10   06   12   05.3   06   055   122   1910   086   2001   008   1956   09   09.5   06   068   104   1910   175   1914   10   1933   01   00   01  
  Thorney Island   09.9   +1.6   05.8   +2.1   14.0   04   -02.8   21   08   04   14   06.2   20   060   099   1958   114   2001   037   1966   10   21.8   02   098   128   1941   165   1993   19   1953   00   00   01  
  *Wattisham   08.2   +1.7   04.2   +1.4   13.5   04   -03.6   22   11   06   15   06.6   09   050   101   1979   082   1999   022   2002   13   09.6   06   045   082   1964   120   1965   24   1988   00   00   02  
  *Wittering   08.4   +1.9   04.5   +1.9   13.9   04   -02.9   22   11   04   10   06.2   16   052   104   1950   082   2001   020   1956   13   14.6   30   054   094   1948   130   1978   07   1963   00   00   03  
                                                                     
  Lyneham   08.2   +1.0   04.5   +1.7   12.9   04   -05.7   20   08   03   15   06.4   16   041   082   1952   083   2001   017   1956   13   15.8   31   092   119   1945   159   1959   16   1988   00   00   03  
  Ross-on-Wye   08.8   +1.4   04.3   +0.9   14.0   01   -02.0   21   00   04   17   05.6   16   040   081   1915   078   1948   012   1989   04   20.3   30   105   140   1859   197   1929   11   1991   00   00   03  
  *St Athan   09.3   +1.3   05.9   +1.8   13.0   29   -01.5   21   05   03   17   05.7   16   036   078   1954   072   2001   003   1956   12   16.0   30   113   113   1954   208   1965   31   1988   00   00   01  
  St Mawgan   10.2   +0.9   06.5   +0.9   13.5   04   -00.9   22   06   01   12   07.5   21   071   129   1945   103   2001   027   1988   09   15.4   02   102   083   1944   233   1959   30   1991   00   00   00  
                                                                     
  *Edgbaston   08.3   +1.4   04.8   +2.3   13.6   04   -02.5   22   08   03   10   04.9   16   046   103   1887   090   1891   005   1890   10   16.2   29   090   131   1887   166   1965   10   1926   01   00   01  
  *Valley   09.7   +0.8   06.6   +1.2   12.9   04   01.4   19   05   00   09   05.2   11   041   084   1946   080   1960   025   1998   14   21.6   02   140   143   1941   179   1964   17   1963   01   00   00  
  *Woodford   08.3   +1.5   04.3   +2.0   13.1   14   -01.4   21   10   02   13   04.2   11   031   075   1945   075   2001   016   1947   09   15.6   04   121   144   1942   180   1965   11   1963   00   00   03  
  *Watnall   08.0   +1.5   04.4   +1.8   13.5   04   -03.8   22   08   03   14   05.4   16   045   089   1948   075   2001   012   1956   09   13.6   04   068   120   1941   180   1965   19   1963   00   00   03  
                                                                     
  *Leeming   07.5   +0.5   03.4   +1.1   13.6   14   -05.6   21   13   06   12   06.0   17   066   156   1945   077   1967   014   1972   08   10.6   02   070   110   1945   125   1978   16   1988   00   00   02  
  *Boulmer   07.8   +0.9   03.5   +1.1   13.4   13   -01.4   18   11   06   09   06.0   06   * 082   183   1945   077   1967   021   2002   14   07.8   03   038   059   1945   205   1978   17   1975   00   00   01  
  *Eskdalemuir   06.1   +0.7   01.9   +1.1   10.6   13   -08.0   25   16   08   14   05.3   18   030   080   1911   074   1967   003   1912   07   74.0   13   331   195   1911   351   1993   33   1933   00   00   02  
  *Bishopton   07.7   +0.5   03.8   +1.6   11.5   10   -01.4   19   16   02   13   05.5   08   038   119   1921   072   2001   009   1956   05   61.2   13   * 295   260   1921   261   1999   15   1933   00   00   01  
                                                                     
  *Leuchars   07.1   +0.4   02.4   +0.3   13.4   10   -03.2   18   20   09   10   05.5   06   067   131   1921   082   1967   016   1934   09   06.6   12   050   074   1921   155   1978   08   1926   01   00   01  
  *Dyce   07.2   +0.8   01.2   -0.3   14.1   13   -07.1   21   18   11   05   05.2   06   * 088   196   1941   067   1951   016   2002   13   10.0   31   030   035   1941   160   1978   20   1991   00   01   00  
  *Stornoway   08.5   +1.0   05.5   +2.2   12.8   13   00.1   16   08   00   16   04.1   18   017   069   1880   057   1995   006   1884   05   18.4   03   181   137   1943   222   1985   29   1977   01   01   00  
  *Aldergrove   07.7   +0.6   03.9   +1.0   12.3   10   -02.7   21   09   02   10   05.4   16   051   145   1927   077   2001   017   1954   06   08.4   06   073   076   1927   195   1978   15   1963   00   00   01  
                                                                     
                                                                                                                                             
  Stations marked with an asterisk record sunshine electronically; comparisons      
  with earlier records are therefore somewhat speculative. Thorney Island's   * New highest record   * New highest record  
  sunshine figures are made at a nearby site.