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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 14°C widely, with 15°C 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 13.6°C. 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 12-13°C 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 -7°C, and on the morning of the 25th -9.4°C 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 -2.6°C 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, Aberdeen’s 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 0ºC
   
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