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graphs      CLIMATE-UK.COM'S  REVIEW  OF  THE  BRITISH  METEOROLOGICAL  SCENE
     MONTHLY  SUMMARY
     No. 588 For   DECEMBER  2004
      ANTICYCLONIC FIRST HALF, THEN UNSETTLED BUT QUITE SUNNY
Text Box: An anticyclonic/southwesterly type lasted until the 14th, followed by a spell of disturbed westerly weather until the 24th. A brief northerly interlude delivered a white Christmas to northern and western districts, but unsettled westerlies returned for the remainder of the month. Mean sea-level pressure for the month ranged from 18mbar below normal in the Norwegian Sea to 10mbar above north of the Azores, and this was the most ‘westerly’ December over the British Isles since 1986.

Pressure was high over southern Britain for much of the first half of December, with westerly or southwesterly winds over northern regions. Rain on the 1st was mostly light and sporadic - indeed, most southern, central and eastern parts of the UK had no significant rain during the first two weeks of December. By contrast northern and western Scotland had frequent rain, heavy at times, with 54mm at Cassley(Sutherland) on the 4th/5th, and 103mm at Loch Sloy (Argyll) on the 13th/14th, while Broadford (Skye) recorded rain every day from November 3 to December 12.  Many places in central and southern England endured a long sequence of overcast, gloomy and rather misty days, but even here there were occasional bright spots; meanwhile northern England and eastern Scotland enjoyed several sunny days. Highest daily duration was 7.5 hours at Jersey airport on the 3rd. Fog was often a hazard, and on the 2nd it persisted all day in many parts of central and southern Scotland, Cumbria and North-umberland, and at Glentress (Peebles) the day’s high was just 0.3șC. It became very mild for several days, especially between the 4th and the 9th, with afternoon maxima often between 10 and 14șC, but thanks to a southeasterly drift off the continent England was very cold on the 13th with a high of 0.7șC at High Wycombe (Bucks). 

Mild, changeable weather spread to all parts of the UK on the 14th and 15th, the temperature reaching 13.7șC at Lossiemouth (Moray) on the former date, and the rain which fell early on the 16th was the first for 19 days locally in southern England. It then turned colder for several days with snow and hail showers in northern Britain, but a rapidly deepening secondary depression tracked from Pembrokeshire to Kent on the morning of the 18th bringing heavy rain and gales to southern districts (the wind gusted to 72 kn at North Hessary Tor in Devon),
Text Box: and another depression crossed Cornwall and Devon overnight 19th/20th with further heavy rain (55mm at Exeter) and snow over high ground in south Wales and the West Country.  Meanwhile under clear skies the temperature fell to -15.2șC at Kinbrace (Sutherland) early on the 20th, and climbed no higher than -1.8șC at Loch Rannoch (Perthshire) during the day. It now became milder again for a few days as vigorous depressions tracked between Scotland and Iceland, and heavy rain returned to western and northern Scotland accompanied by gale force winds. 

The westerly flow veered northwesterly on the 24th in the wake of a secondary depression which crossed Northern Ireland and southern Scotland and temperatures slumped sharply in all regions. Showers, mostly of hail, sleet or snow, fell widely in Scotland, Northern Ireland, northwest England, Wales, the western Midlands, and parts of the West Country on the 25th and 26th, but remaining districts remained mostly dry and sunny although frost developed widely at night. It became slightly less cold from the 27th, and an active cold front brought heavy rain (54mm at Capel Curig, in Snowdonia) accompanied by hail and thunder in places, later that day and during the following night. After a sunny day on the 28th it became mostly cloudy but very mild during the closing days of the month, and prolonged rain again affected the western highlands with 53mm at Cassley in Sutherland; the temperature approached 16șC at Colwyn Bay on the 30th. 

In most regions December 2004 was a mild month with mean monthly temperature anomalies of +1.0 to +1.5 degC, but in parts of East Anglia and the Southeast the month ended up within a couple of points of the 1971-2000 normal. It was a very dry December in eastern counties from Cambridgeshire to Fife where several sites recorded less than 15mm, but monthly totals exceeded 750mm over the hills of Wester Ross, Lochaber, Skye and Argyll. In spite of the very dull first fortnight much of the UK reported above-normal monthly sunshine aggregates, and excesses of 60 per cent or more were logged in north Wales, the north Midlands, Norfolk, Lincolnshire, Yorkshire and Shetland. By contrast Stornoway in the Western Isles and Prestwick in Ayrshire fell some 30 per cent short of the average.
                                                                                                                                         
                       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 0șC
   
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
           
                                                                     
      șC       șC       șC       șC             Hrs       Hrs         Hrs       Hrs       mm       mm         mm     mm          
                                                                                                                                         
  *Hampstead   07.9   +0.2   02.6   +0.2   12.5   23   -03.3   26   18   00   08   06.4   26   053   117   1910   085   1962   008   1956   19   14   17   048   077   1910   175   1914   10   1933   00   00   00  
  Thorney Island   08.8   +0.2   04.0   +0.3   12.7   23   -02.4   27   14   06   14   06.8   28   041   069   1958   114   2001   037   1966   16   28   18   070   096   1941   165   1993   19   1953   00   00   00  
  *Coltishall   08.0   +0.9   02.5   +0.0   13.2   23   -04.7   20   20   08   06   06.2   11   069   139   1979   082   1999   022   2002   15   09   27   029   049   1964   120   1965   24   1988   00   00   01  
  *Wittering   07.8   +1.3   02.7   +0.1   12.4   23   -04.3   03   17   04   05   06.5   11   073   145   1950   082   2001   020   1956   20   07   27   017   032   1948   130   1978   07   1963   00   00   01  
                                                                     
  Lyneham   07.3   +0.1   03.1   +0.3   11.6   30   -03.6   27   17   04   11   06.8   19   053   106   1952   083   2001   017   1956   16   20   18   053   073   1945   159   1959   16   1988   01   02   00  
  Ross-on-Wye   08.4   +1.0   03.3   -0.1   13.0   22   -05.0   20   13   05   08   06.1   19   059   120   1915   078   1948   012   1989   16   10   19   037   052   1859   197   1929   11   1991   00   02   00  
  *St Athan   09.0   +1.0   05.1   +1.0   11.6   23   -02.3   20   08   02   08   05.6   19   050   109   1954   072   2001   003   1956   13   34   16   124   132   1954   208   1965   31   1988   00   01   00  
  St Mawgan   09.9   +0.6   06.2   +0.6   11.9   30   00.1   20   05   00   12   06.6   01   059   107   1945   103   2001   027   1988   14   13   18   071   061   1944   233   1959   30   1991   01   00   00  
                                                                     
  *Edgbaston   07.6   +1.0   04.1   +0.7   12.5   30   -01.0   20   12   03   05   05.1   01   056   127   1887   090   1891   005   1890   18   08   21   029   024   1887   166   1965   10   1926   00   01   00  
  Valley   09.6   +0.7   05.8   +0.4   12.0   06   -00.2   20   07   01   13   06.1   15   049   099   1946   080   1960   025   1998   09   20   21   070   077   1941   179   1964   17   1963   00   01   00  
  Ringway   08.2   +1.0   03.4   +0.4   12.8   30   -04.9   27   12   06   10   06.4   26   050   121   1945   075   2001   016   1947   10   12   21   080   101   1942   180   1965   11   1963   01   02   00  
  *Watnall   07.6   +1.1   03.6   +1.0   12.2   23   -02.8   20   14   04   05   06.5   26   064   128   1948   075   2001   012   1956   14   06   27   022   041   1941   180   1965   19   1963   00   00   00  
                                                                     
  Leeming   07.9   +0.9   02.4   +0.1   13.3   22   -06.5   20   17   06   08   06.2   02   068   161   1945   077   1967   014   1972   17   09   30   025   041   1945   125   1978   16   1988   00   00   01  
  *Boulmer   08.2   +1.3   02.8   +0.4   13.3   22   -02.1   10   19   03   04   06.0   02   070   156   1945   077   1967   021   2002   14   08   30   020   034   1945   205   1978   17   1975   00   01   00  
  Eskdalemuir   06.2   +0.8   01.8   +1.0   10.1   14   -06.6   20   17   10   16   06.0   26   043   117   1911   074   1967   003   1912   07   21   27   166   104   1911   351   1993   33   1933   01   05   00  
  *Bishopton   07.6   +0.4   03.6   +1.4   11.7   30   -02.5   20   16   07   14   05.7   19   038   118   1921   072   2001   009   1956   02   22   14   180   169   1921   261   1999   15   1933   00   03   02  
                                                                     
  Leuchars   07.7   +1.0   02.2   +0.1   12.7   22   -04.2   19   19   10   10   05.9   02   076   149   1921   082   1967   016   1934   19   04   22   020   031   1921   155   1978   08   1926   00   02   00  
  Dyce   07.6   +1.2   02.6   +1.1   12.0   14   -05.4   19   17   07   08   05.7   02   066   147   1941   067   1951   016   2002   18   11   14   033   042   1941   160   1978   20   1991   00   05   00  
  *Stornoway   08.2   +0.7   04.5   +1.2   11.9   29   -03.1   19   12   03   14   02.6   07   017   069   1880   057   1995   006   1884   02   12   27   136   109   1943   222   1985   29   1977   02   05   00  
  *Aldergrove   08.1   +1.0   03.9   +1.0   11.7   30   -01.3   02   14   03   14   06.1   19   044   127   1927   077   2001   017   1954   06   12   16   068   076   1927   195   1978   15   1963   00   02   01  
                                                                     
                                                                                                                                         
  Stations marked with an asterisk record sunshine electronically; comparisons      
  with earlier records are therefore somewhat speculative. Thorney Island's      
  sunshine figures are made at a nearby site.