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graphs      CLIMATE-UK.COM'S  REVIEW  OF  THE  BRITISH  METEOROLOGICAL  SCENE
     MONTHLY  SUMMARY
     No. 624 For   DECEMBER  2007
          VERY MILD AND WET EARLY AND LATE; LONG ANTICYCLONIC INTERLUDE 11TH-24TH
Text Box: December comprised three contrasting episodes: a cyclonic/southwesterly type held sway until the 10th followed by a long anticyclonic period from the 11th-24th, then a changeable southwesterly regime returned for the last week. Mean monthly sea-level pressure anomaly ranged from +1mbar in the Western Isles to +6mbar in Kent, and the anomalous flow over the British Isles was south-southwesterly. The month opened with a complex depression over Scotland and a vigorous west to southwesterly flow over southern Britain. A brief northwesterly incursion on the 3rd was followed by a broad southwesterly airstream which lasted from the 4th to the 6th. A deep depression crossed the British Isles on the 8th/9th followed by a prolonged strong pressure rise. The first three days of December were unsettled and rather mild with a good deal of rain especially in Scotland and Northern Ireland, local thunderstorms too, but also some long sunny spells especially on the 1st and 3rd. It was windy in southern districts, and Guernsey airport reported a gust of 70kn on the 2nd. The 4th, 5th and 6th were exceptionally mild and mostly cloudy days with prolonged orographic rainfall on western upslopes. The temperature exceeded 14°C widely, with 16.2°C at Prestatyn (Denbighshire) on the 6th. Capel Curig recorded 56mm of rain on the 6th alone, part of a 13-day total there of 322mm between 27 Nov and 9 Dec. The 7th was quite sunny, but wet and windy weather affected all districts during the next two days. The rain cleared away eastwards on the 10th but it was now appreciably colder. A high pressure cell formed over England on the 11th, and from then until the 21st a large anticyclone lay just to the east of the UK, and a southeasterly airflow, often very sluggish, covered the country for much of the time. The high receded eastwards after the 21st allowing weak Atlantic fronts to advance across Britain on the 22nd and 24th.
Text Box: Throughout this period the weather was dry, settled, and generally cold. There was a good deal of sunshine by day, but nights were often very frosty and there were persistent some freezing fog patches too. Temperatures in Scotland fell below -10°C on six consecutive nights from the 16th/17th to the 21st/22nd, with a lowest reading of -13.0°C at Aboyne (Aberdeenshire) early on the 22nd. Afternoon maxima below zero were common during this period, and were most widespread on the 21st when Aberfeldy (Perthshire) climbed no higher than -4.2°C. Patchy light rain brought a general rise in temperature on the 22nd, but many places in England and Wales had no measurable rain between the 10th and 24th inclusive. A cold front moved erratically across England and Wales on the 25th followed by mainly southwesterly winds until the 29th, but a ridge of high pressure developed over England on the last two days. Christmas Day was wet over much of England and Wales (the wettest in London since 1989), but Scotland and Northern Ireland were cold and frosty. The next few days were mild and windy with the temperature reaching 13°C locally, and there was heavy orographic rainfall in upland western districts: Shap (Cumbria) recorded 181mm between the 24th and 29th with 80mm on the 27th alone. The end of the month was generally cloudy and less mild with rain confined to northern and western Scotland and Northern Ireland. Both mean maximum and mean minimum temperature was within 0.5degC of the long-term normal in nearly all parts of the UK. Rainfall was above average in some upland parts of western Scotland, Cumbria and Wales, but it was below everywhere else, and several sites in eastern Britain from Essex to Fife recorded less than 25mm during the month. Much of the UK was sunnier than average with aggregates of 80-90 hours in southern England, but some eastern and midland counties had rather less sunshine than usual with a monthly total of barely 30 hours in parts of Yorkshire, Lincolnshire and Nottinghamshire.
                                                                                                                                             
                       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