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graphs      CLIMATE-UK.COM'S  REVIEW  OF  THE  BRITISH  METEOROLOGICAL  SCENE
     MONTHLY  SUMMARY
     No. 585 For SEPTEMBER 2004
DRY,SUNNY AND VERY WARM AT FIRST TILL THE 10TH, THEN CHANGEABLE AND OFTEN WINDY
Text Box: Mumbles, near Swansea, measured a gust of 74 mph. Amounts of rain were relatively small in some eastern parts of Scotland and England, but huge orographically-enhanced totals were recorded in the western Highlands, the Lake District, and Snowdonia. Largest 24-hour totals were 75mm at Capel Curig, Snowdonia, on the 12th and 70mm at Loch Sloy, Argyllshire, on the 19th. Here, 368mm fell in the 12-day period ending on the 21st. For much of this period temperatures were near normal, but it turned cold on the 23rd/24th as the wind veered; the maximum at Lerwick, Shetland, on the 24th was 9.6ēC, and the minimum at Redhill airfield, Surrey, overnight 24th/25th was -0.6ēC. From the 25th till the month’s end high pressure lay over Biscay and France but a cloudy westerly airflow covered most of the UK, and most regions had occasional rain although amounts were small over England and Wales until the 30th. Days were cool but nights were mostly mild, and Eskdalemuir had a sunshine aggregate of just 0.8 hour during the last six days. Monthly mean temperature was around 1 degC above the long-term average in all regions, but this was almost entirely due to the warmth of the first ten days. In eastern, central and southern regions this was the third consecutive dry September, and only 10mm of rain fell at Dishforth, North Yorkshire, and12mm at Boulmer, Northumberland, where it was the driest September since 1971. By contrast, Loch Sloy collected 460mm, and an estimated 500-600mm fell in the wettest locations in the southwest Highlands, the Lake District and Snowdonia. Thanks to the exceptionally sunny start, monthly sunshine totals were above average nearly everywhere in the UK, and Aberdeen airport’s 181 hours was a new record for the site, making this the sunniest September in the Aberdeen area district since 1906.
Text Box: Pressure was high over the UK until the 9th, but winds from a westerly quarter blew throughout the remainder of the month. Mean sea-level pressure was above normal in the Europe/Atlantic sector south of latitude 55N and below normal further north, resulting in an enhanced westerly flow over the British Isles where it was the tenth most westerly September in the last 100 years. High pressure lay over southern Britain from the start of the month, extending to all parts of the UK from the 5th-9th and the barometer climbed to 1040.6mbar early on the 7th at Inverbervie, Kincardineshire (a new UK record for the first half of September). A trough advanced from the southwest on the 10th as the high receded eastwards. There was occasional rain in Scotland at first, notably on the 3rd, and showers over England and Wales on the 10th, otherwise the weather was dry, sunny and very warm throughout the first ten days. In fact this was the driest and sunniest start to September since 1991. The temperature widely reached 22-25ēC daily, peaking at 29.0ēC at Wisley, Surrey, on the 5th, while the 6th was the hottest September day in the Cardiff area since 1961. In Scotland, Glenlivet, Moray, touched 26.0ēC on the 9th. Bournemouth recorded 103 hours of sunshine during the first nine days. Vigorous depressions tracked north-eastward past northern Scotland between the 11th and 14th followed by a transitory ridge on the 15th, then a large complex depression moved slowly eastward between Scotland and Iceland from the 16th-20th and settled over Scandinavia around the 21st-24th allowing a brief north-westerly intrusion across the British Isles. This was the most disturbed period of the month with belts of rain crossing all parts of the country at frequent intervals, sunshine and showers between the rain-belts, and gale force winds especially in Scotland but also in Wales and south-west England on the 14th when
                                                                                                                                             
                       TEMPERATURE                                SUNSHINE                             RAINFALL                                                       
                                                                                                                                     
                                                                                                                                     
                   
No. of days with grass minimum below 0ēC
                      Highest and lowest totals    
Maximum fall in 24 hrs (beginning 09 h)
                Highest and lowest totals    
Days with snow or sleet
 
Days with fog (Vis <220 yards at 09 h)
 
     
Difference from average
   
Difference from average
             
Days of no sunshine
                      on record for month                         on record for month        
                                                                                         
           
Highest maximum
   
Lowest minimum
         
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