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graphs      CLIMATE-UK.COM'S  REVIEW  OF  THE  BRITISH  METEOROLOGICAL  SCENE
     MONTHLY  SUMMARY
     No. 628            For    APRIL    2008
    A SHOWERY MONTH WITH FREQUENT HAIL AND THUNDER; COLD PERIOD 5TH-19TH
Text Box: The north-westerly and northerly winds which had so dominated March returned from the 5th-16th, but the remainder of the month was rather episodic with short easterly, south-westerly, anticyclonic and cyclonic spells. Over the month as a whole, pressure was below normal over Europe and the Atlantic south of latitude 60degN but above normal further north, and markedly so over Greenland. Over the UK it was both the most northerly and the most cyclonic April for seven years. The first four days were rather cloudy but warm with high pressure centred near south-western Britain and a moist westerly airflow covering the country; the best of the limited sunshine was found along the English Channel coast. The temperature reached 15-18°C widely, with 18.9°C at Inverbervie (Kincardineshire) on the 3rd. A strong rise of pressure in the Iceland area led to the development of a deep northerly flow between the 5th and 7th; temperatures dropped sharply, there was extensive frost at night and widespread wintry showers by day, and on the 6th a trough embedded in the northerly flow brought a longer period of snow which was heaviest in Southeast England and the Thames Valley - a snow-depth of 11cm was noted at several locations in Oxon, Berks, Hants, Surrey and Kent. That morning’s lows included -6.0°C at Warcop (Cumbria), while afternoon maxima were no higher than 1.9°C at East Malling (Kent) and 2.0°C at Kenley (Surrey) making this the coldest April day in these counties possibly since 1966. Lerwick (Shetland) reported a gust of 57kn, the month’s highest. Low pressure lay over or close to the British Isles from the 9th to the 15th, maintaining a very showery regime; some of the showers were heavy and prolonged, often falling as hail, and occasionally accompanied by thunder. Showers were fewest, and sunny spells longest, in western and southern coastal districts. Daytime temperatures remained well below the seasonal norm in all regions, while frost developed widely at night, and the lowest temperatures of the month occurred overnight 13th/14th and 15th/16th with minima of -6.8°C and -6.6°C respectively, both at Braemar (Aberdeenshire).
Text Box: A brisk east to north-easterly flow covered the UK from the 16th-22nd, maintaining the generally cold weather. All eastern, central and southern districts were cold and dull during the 17th-19th with rain at times, but it became less cold and somewhat brighter here from the 20th. Western Scotland, meanwhile, enjoyed prolonged sunshine, but with frosty nights. Altnaharra (Sutherland) logged -5.1°C on the morning of the 21st, while Tiree (Inner Hebrides) recorded 112h of sunshine in the 10-day period 12th-21st. The flow veered south-westerly from the 23rd-26th, bringing showers or longer periods of rain to all areas, and Broadford (Skye) collected 42mm on the 25th. It became progressively warmer, and the 26th was a fine and very warm day with the temperature climbing above 20°C quite widely, and reaching 22.0°C at Weybourne (Norfolk). The mercury fell no lower than 13.4°C the following night at Hampstead (London). It was only slightly less warm on the 27th, but showers and thunderstorms broke out quite widely that day and the next. A deep depression crossed southern England on the 29th and 30th (central pressure 985 mbar) bringing periods of rain, heavy at times, to nearly all parts of the country. Both mean maximum and mean minimum temperatures were within 0.5 degC of the long-term average in all regions; nonetheless it was the coldest April since 2001. Although rain fell frequently, often in showery form, amounts were generally not large (except on the 29th-30th) and it was actually a moderately dry month over much of East Anglia, the Midlands, northwest England and Northern Ireland. Hail was unusually frequent, being reported on as many as 12 days at some sites. As for sunshine, there was a marked contrast between inland parts of northern England and southern Scotland where it was a very cloudy April, and western and southern coastal districts where it was a sunny one. Sunshine totals ranged from 85 hours at Eskdalemuir (Dumfriesshire) to 238 hours at Portland (Dorset) and 240 hours at Guernsey airport (Channel Is).
                                                                                                                                             
                       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
         
Date
         
Year
         
Date
         
Year
           
                                                                     
      ºC       ºC       ºC       ºC             Hrs       Hrs         Hrs       Hrs       mm       mm         mm     mm          
                                                                                                                                             
  *Hampstead   12.9   +0.6   04.7   +0.4   21.1   26   -01.7   07   09   05   02   09.1   22   136   106   1910   240   1912   087   1920   13   15   29   056   122   1910   123   2000   02   1912   01   01   00  
  *Thorney Island   13.0   -0.4   05.2   +0.4   17.3   22   -02.8   08   08   05   02   12.5   26   193   113   1956   262   1990   101   1966   9   29   29   072   160   1941   111   2000   00   2007   01   01   00  
  *Wattisham   12.5   +0.4   03.7   +0.2   20.5   26   -02.9   07   12   04   01   10.3   22   163   117   1968   254   1990   123   2006   8   13   29   039   099   1960   109   1998   02   2007   04   02   01  
  *Wittering   12.0   +0.2   03.6   -0.2   19.9   26   -02.4   16   15   05   02   10.0   17   138   094   1950   221   1984   077   1978   16   10   29   033   083   1948   142   1998   03   2007   05   02   00  
                                                                     
  Lyneham   12.3   +0.3   03.9   0.0   19.1   26   -01.3   07   15   05   01   12.7   17   184   118   1952   243   1984   084   1961   18   08   29   024   053   1946   153   2000   01   1984   04   02   01  
  Ross-on-Wye   13.2   +0.9   04.3   -0.4   20.0   26   -03.0   14   10   05   04   11.5   11   157   109   1915   229   2007   072   1920   7   10   29   060   137   1859   173   2000   00   1957   02   01   00  
  *St Athan   11.6   -0.4   04.9   +0.4   18.2   26   -01.1   08   11   02   04   11.9   12   186   111   1954   253   1984   091   1966   10   08   29   042   079   1954   125   2000   02   1957   01   01   00  
  St Mawgan   11.3   -0.4   05.6   +0.1   15.7   20   00.3   08   07   00   05   13.0   16   223   117   1944   266   1984   125   1966   10   10   29   052   100   1945   142   1998   02   1984   01   00   00  
                                                                     
  *Edgbaston   11.6   +0.3   04.7   +0.5   18.0   26   -02.2   06   10   01   02   10.8   26   139   111   1887   242   2007   091   1891   9   17   29   057   093   1887   137   1998   02   1938   04   02   00  
  *Valley   10.8   -0.7   05.7   +0.4   15.3   22   -00.2   06   09   01   04   11.3   16   168   091   1946   247   1974   123   1996   11   16   29   083   160   1941   103   1961   07   1980   01   00   00  
  *Woodford   11.4   -0.3   03.8   +0.2   17.3   26   -04.9   06   14   06   03   09.0   15   104   080   1945   216   1984   095   1961   8   13   11   069   137   1942   107   2001   04   1980   03   01   00  
  *Watnall   11.5   -0.3   04.0   +0.2   19.2   26   -01.8   06   13   02   03   07.9   14   107   073   1948   220   1984   071   1971   9   11   29   070   175   1942   135   2000   06   1957   04   02   00  
                                                                     
  *Leeming   11.9   +0.1   02.9   -0.7   18.3   03   -03.8   06   19   07   02   09.3   01   090   067   1945   213   2007   088   1971   8   13   29   056   144   1945   140   2000   05   1954   02   02   00  
  *Boulmer   09.9   -0.3   03.9   +0.3   16.9   03   -01.3   06   01   01   00   10.8   19   117   080   1945   218   1984   083   1974   9   19   27   106   266   1945   156   1998   03   1980   01   02   00  
  *Eskdalemuir   09.6   -0.8   01.9   +0.3   14.9   27   -04.6   06   19   12   02   07.8   17   085   063   1911   197   1942   059   1996   8   12   25   080   093   1911   254   1947   17   1980   02   04   00  
  *Bishopton   11.7   -0.3   03.8   +0.4   15.3   27   -01.0   06   14   02   01   10.8   14   129   085   1921   205   1962   073   1937   12   08   01   061   121   1921   159   1947   05   1974   02   02   00  
                                                                     
  *Leuchars   10.4   -0.7   03.7   +0.4   17.1   03   -02.2   06   15   02   01   12.7   19   162   100   1922   217   1990   098   1937   5   15   27   069   178   1922   117   1934   02   1938   01   02   00  
  *Dyce   09.9   -0.6   03.0   +0.4   18.0   26   -03.1   10   17   03   04   12.7   20   146   098   1941   212   1942   085   1941   08   25   08   086   172   1941   131   2000   10   1946   00   02   00  
  *Stornoway   09.9   -0.1   03.8   +0.2   14.8   03   -00.9   09   14   01   01   13.5   17   178   114   1880   230   1962   095   1944   10   11   25   069   105   1943   144   1947   01   1974   00   03   00  
  *Aldergrove   11.9   0.0   04.2   +0.2   16.3   23   -01.0   06   11   03   01   11.4   14   173   116   1927   220   1974   057   1937   12   04   07   021   044   1927   117   1986   06   1938   01   01   00  
                                                                     
                                                                                                                                             
  Stations marked with an asterisk record sunshine electronically; comparisons      
  with earlier records are therefore somewhat speculative. Thorney Island's      
  sunshine figures are from a nearby site.