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graphs CLIMATE-UK.COM'S REVIEW OF THE BRITISH METEOROLOGICAL SCENE
MONTHLY SUMMARY
No. 661 For JANUARY 2011
UNSETTLED UNTIL JUST AFTER MID-MONTH THEN ANTICYCLONIC
Text Box: The opening days of January were anticyclonic, but a cyclonic spell followed between the 4th and 11th which in turn gave way to a broad southwesterly flow between the 12th and 16th. Thereafter strong rises of pressure led to a mostly anticyclonic second half of the month. The dominant sea-level pressure anomaly centre was one of +10mbar centred to the southwest of Iceland, and the anomalous flow over the UK was northerly with an anticyclonic bias.

With high pressure west of Ireland, and southward-moving cold front brought some rain, drizzle and hill fog on the 1st, followed by drier and colder weather in Scotland. Much of the country was dry on the 2nd, but some rain and snow affected both northern Scotland and southwest England, and this rather wintry mix became rather more widespread on the 3rd as pressure fell progressively. The next three or four days were cold and unsettled with substantial falls of rain (with hill snow) over southern England and south Wales, amounting to 25-45mm in several places. Between the 6th and 8th the lowest temperatures of the month occurred in Scotland where there were sporadic outbreaks of snow and also some freezing fog; Edinburgh airport was closed by snow for most of the 8th. On the 7th the day's high was -3.9C at Strathallan (Perthshire), and the following night the minimum reading was -13.0C at Altnaharra (Sutherland). Overnight 7th/8th milder air spread northwards as far as the Scottish border, but the 9th was rather cold though mainly sunny over England and Wales, while the 10th was a wet day. A very mild southwesterly airflow covered the British Isles between the 12th and 16th bringing grey skies and widespread rain; there were some heavy orographically-enhanced falls in upland western districts, including a 48-hour total of 149mm at Capel Curig (Caernarfon) and a seven-day total (10th-16th) of 267mm at Honister Pass (Cumbria). Over much of the country temperatures remained above 10C for much of the period; the highest maximum was 14.5C at Pershore (Worcs) on the 13th, while the highest overnight minimum was 11.8C at Exeter (Devon) early on the 13th and at Linton-on-Ouse (N Yorks) early on
Text Box: the 16th. Gusts to 66kn were noted at Capel Curig on both the 15th and 16th. On the 16th a cold front brought a drop in temperature, but the front lingered near southern England for 48 hours during which period 25-40mm of rain fell over a wide area.

From the 18th until the end of the month high pressure controlled Britain's weather. Until the 22nd it lay over the country, thence drifting to a position west of Ireland until the 26th, before returning to the UK as a slowly declining feature from the 27th onwards. Freezing fog formed widely between the 18th and 21st, clearing to sunshine in many places during the day, and many western districts enjoyed prolonged sunshine during this period, though with sharp overnight frosts; Katesbridge (Co Down) recorded -9.8C early on the 20th, and Llysdinam (Breconshire) logged -9.2C the following morning. As the high moved west, a cloudier northwesterly flow affected the country, bringing outbreaks of mostly light rain and drizzle, a good deal of hill fog, and somewhat higher temperatures, but from the 27th onwards it became mostly dry and colder again with night frosts. There were snow flurries in some eastern districts where it was largely cloudy, but western districts again had plenty of sunshine and severe night frosts. Aberporth (Cardiganshire) recorded 8.5 hours of bright sunshine on the 28th, while Sennybridge (Breconshire) reported a minimum temperature of -10.4C early on the 31st.

Mean monthly temperatures were close to the 1971-2000 average in eastern districts, but up to a degree below in western Britain and Northern Ireland. It was a wet month over much of southern England, but notably dry in northeast England, parts of eastern Scotland, and also in Northern Ireland. The month's total at Dishforth (N. Yorks) was just 14mm. East Anglia and Southeast England had a dull month, but sunshine aggregates were above normal elsewhere, with excesses in Northern Ireland of around 60 per cent.
                                                                                                                                             
    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   06.0   -0.4   02.4   +0.7   12.3   13   -01.8   29   17   09   10   06.3   09   041   093   1910   096   2003   020   1917   10   19.8   17   093   141   1910   131   1995   14   1914   00   00   03  
  Thorney Island   07.1   -0.6   03.0   +0.2   11.3   13   -02.7   10   09   06   05   08.5   30   068   112   1958   105   2003   035   1975   10   18.2   16   104   132   1941   160   1988   12   1987   00   00   00  
  Wattisham   06.1   +0.3   02.1   +0.2   12.8   16   -01.2   29   18   10   16   07.0   09   042   073   1968   093   2001   022   1996   10   13.2   17   067   137   1960   133   1988   06   1997   00   02   05  
  Wittering   06.3   +0.5   01.7   +0.1   13.2   13   -05.5   21   16   10   09   07.4   31   049   087   1950   096   1959   016   1996   18   06.8   07   029   053   1948   107   1948   12   2000   00   01   04  
                                                                     
  Lyneham   05.5   -0.7   01.4   -0.4   11.5   13   -04.8   31   18   11   13   07.9   20   053   097   1952   088   1952   027   1996   10   17.6   12   094   138   1945   132   1995   06   1997   00   02   05  
  Ross-on-Wye   06.7   -0.2   01.3   -1.2   13.0   12   -03.8   22   22   14   16   06.7   09   050   091   1915   096   1952   017   1996   16   12.5   13   063   087   1859   161   1943   07   1898   00   00   02  
  St Athan   06.7   -0.3   02.1   -0.9   11.7   16   -05.9   31   16   09   13   07.0   30   049   092   1954   085   1959   021   1996   11   21.4   12   108   119   1954   172   1995   09   1997   00   00   01  
  Culdrose   07.9   -0.9   03.2   -1.8   11.3   07   -03.3   31   16   09   13   07.8   30   083   140   1961   107   2010   029   1982   10   17.0   17   090   074   1961   255   1984   22   1964   00   01   00  
                                                                     
  Edgbaston   05.8   -0.9   01.9   -0.5   12.7   13   -03.5   00   19   11   04   07.3   31   049   100   1887   077   1952   007   1917   16   08.6   07   033   043   1887   153   1960   13   1888   00   00   06  
  Valley   07.0   -0.9   02.5   -1.7   10.2   15   -03.4   29   15   09   09   08.1   28   074   124   1946   094   2001   024   1983   13   11.0   07   048   053   1941   195   1948   07   1997   00   00   00  
  Woodford   05.8   -0.2   00.8   -0.7   11.8   13   -05.0   29   21   14   15   07.5   28   037   067   1945   074   2003   011   1953   11   10.8   04   054   075   1942   170   1948   08   1997   00   01   02  
  Watnall   06.2   +0.4   01.9   +0.2   12.5   13   -04.3   21   17   10   11   07.5   20   056   099   1948   083   2000   013   1996   18   08.8   07   032   059   1942   149   1948   10   1997   00   02   05  
                                                                     
  Leeming   06.4   +0.2   00.4   -1.0   13.0   13   -08.3   21   21   15   12   07.3   20   069   122   1945   091   1959   018   1996   18   06.4   07   020   034   1945   129   1948   06   1997   00   01   05  
  Boulmer   06.5   -0.2   02.4   +0.8   11.5   15   -04.4   07   17   03   11   06.8   20   045   082   1945   104   1959   010   1996   11   13.6   10   036   052   1945   189   1948   09   1989   00   00   03  
  Eskdalemuir   04.3   -0.3   -00.7   -0.5   08.8   13   -10.1   07   23   20   16   07.2   20   049   110   1911   096   1959   009   1996   09   64.4   15   186   117   1911   390   1928   38   1997   00   03   10  
  Bishopton   05.5   -0.9   01.2   -0.1   10.5   15   -06.2   07   20   10   09   05.9   19   055   132   1921   069   1972   009   1940   11   25.0   15   091   088   1921   255   2008   18   1963   00   00   06  
                                                                     
  Leuchars   05.5   -0.6   00.3   -1.0   12.2   15   -07.4   07   29   14   08   06.7   20   053   087   1922   101   1959   014   1996   18   09.4   15   050   078   1922   167   1993   12   1953   00   00   05  
  Dyce   05.9   +0.3   00.9   +0.2   11.1   15   -05.1   09   21   12   07   06.3   20   067   126   1941   089   1959   010   1996   14   08.2   07   043   052   1941   157   1970   13   1989   00   00   08  
  Stornoway   06.6   -0.3   02.6   -0.2   10.7   15   -03.5   07   12   08   15   05.4   27   032   084   1880   079   2001   012   1907   05   09.6   31   106   086   1943   274   1993   26   1963   00   00   03  
  Aldergrove   05.3   -1.1   00.8   -1.1   12.1   15   -08.1   21   20   10   09   07.4   19   071   152   1927   082   1959   024   1996   08   05.2   12   029   034   1927   151   2008   22   1997   00   00   03  
                                                                     
                                                                                                                                             
  Sunshine is recorded electronically at all sites except Ross-on-Wye.      
  Thorney Island's and Edgbaston's sunshine records come from nearby sites.      
  All averages are for 1971-2000