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JULY 2009 daily and monthly summary

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JULY 2009
August
1st - 5th
1st: HP 1025 hPa North Sea, HP 1026 hPa Belarus, slack LPs to W, S and N. 3rd: heavy rain shower 3am. 4th: Weak HP ridge 1015 hPa Luxembourg, LP 999 hPa deepening W of Ireland. 5th, moderate rain around 3am.
6th - 8th
Very unsettled. 6th: LP 999 hPa over N Ireland crossing to NE England, occlusion and trough passes E over southern UK. Heavy rain showers 9am onwards to midday, breezy pm, more rain showers evening. 7th, afternoon - some very heavy thundery showers with hail including a rainfall of 4mm in 10 minutes.
9th - 15th
Slow moving LP 995 hPa tracks ENE into Scandinavia with weak HP ridging over S England. LP 999 hPa SSW of Iceland and more LP to NNW of Azores. 11th, cloudy and mainly dull with rain from warm front after 21h, continuing to 01h on 12th, LP 984 hPa to NW of Ireland, sunny after 11h. 14th, LP now 993 hPa SSW of Ireland with troughs crossing UK W to E, moderate rain shower early evening. 15th showers early and mid morning, sunny pm.
16th - 24th
LP slow moving across the British Isles. Moderate rain with lightning and thunder late evening of 16th followed by passage of trough before midnight. 17th, LP 1002 hPa deepening over eastern England with wrap around occlusion to the SW, rain showers am and late pm. 18th, sunny spells with one rain shower early evening. 19th, LP 996 hPa Orkney/Shetland, occlusion from C Ireland to SE England, heavy rain shower am. 21st, rain showers early morning and afternoon. 22nd, light rain shower early evening. 24th, LP 1002 hPa Scotland - series of troughs bring moderate rain showers am and thunderstorm with heavy rain pm.
25th - 31st
25th, sunny periods with cloudy spells. 26th, maily cloudy with a trace of rain pm. 27th, LP 988 & 991 hPa W and NW of Scotland, light and moderate intermittent rain and showers dawn to midday. 29th, LP 992 hPa NNW of Scotland, light rain from warm front am, heavier rain evening from cold front.
JULY 2009 MONTHLY SUMMARY
ACTUAL TEMPERATURE
 AVERAGE
 Daily Maximum
22.0
  ºC ( -0.6 C )*
 Daily Minimum
13.3
  ºC ( +0.1 C )*
 Daily Mean
16.97
  ºC ( c. -0.3 C )
 EXTREMES
 High Maximum
31.3
  ºC (  2nd )
 Low Minimum
9.9
  ºC ( 10th )
 Low Maximum
18.4
  ºC ( 17th )
 High Minimum
17.3
  ºC (   3rd )
 
   
 Days with max => 25 °C
2
    
 Days with max in range 20 - 25 °C
22
    
 Days with max < 20 °C
7
    
 
PRECIPITATION
 Monthly Total
64.0
  mm ( 143% )*
 Days with measurable precip
19
  Days ( +7 )
   ...of which, days with >= 1.0 mm
17
  Days ( +8 )
   ...and days with hail observed
0
  Days  
 
   
 Days with Thunder
3
  Days  
 RAIN RATE & EXTREMES
 High Rain Rate
126.2
  mm/hr ( 7th )
 High Rain Total in 1 day
9.7
  mm ( 7th )
 High Rain Total in 1 hour
5.1
  mm (3rd, 03.30h )
 EVAPO-TRANSPIRATION
 Total for month
105.3
  mm  
 High Total for 1 day
4.9
  mm ( 13th )
APPARENT TEMPERATURE
 Low Wind Chill
9.9
  ºC ( 10th )
 DAVIS HEAT INDICES THW & THSW
 Low Temp/Hum/Wind Index
9.9
  ºC ( 10th )
 High Temp/Hum/Wind Index
31.3
  ºC (  2nd )
 High Temp/Hum/Sun/Wind Index
37.9
  ºC (  2nd )
 
DEWPOINT & HUMIDITY
 High Dewpoint
17.2
  ºC (  2nd )
 Low Dewpoint
4.4
  ºC ( 30th )
 Average Dewpoint at 14h
11.0
  ºC  
 Low Relative Humidity
30
  % (  1st )
 Average RH at 14h
54
  %  
WIND SPEED & DIRECTION
 Monthly Average
2.7
  mph  
 Windiest day (Average)
4.9
  mph ( 17th )
 Highest Gust
26
  mph ( 19th )
 Dominant Direction
SW
  ( 55% )
 
BAROMETER
 Monthly Mean
1011.7
  hPa  
 High Barometer
1022.8
  hPa ( 31st )
 Low Barometer
1000.2
  hPa ( 23rd )
SUNSHINE
 Max Sensor Exposure to direct sun
10
  hours/day (15-16 possible)
 Calculated Monthly Sunshine Hours
154.6
  hours  
 Estimated Actual Hours (approx)
185.0
  hours  
 Sunniest Day Measured
9.7
  hours ( 1st )
 Days with no sunshine
0
  Days  
 
FOG
 Number of Days with Fog
1
  Days  
NEW RECORDS SET THIS MONTH
  • Equals highest number of rainy days for a July (=1988)
  • Windiest July and July day since anemometer installed in August 2004.
‡ SUN: Sunshine hours are calculated approximately and solely from solar radiation readings, but note that the solar sensor's exposure to sunshine is limited. The sensor receives only up to 70% of total possible sunshine exposure this month due to obstruction. There is no allowance for sunshine by visual observation only, so the sunniest day figures above can be very significantly less than the actual daily sunshine duration.
THW = Shaded Heat Index calculated with cooling/warming effect of wind and humidity to give an apparent temperature.
THSW = Unshaded Heat Index calculated with cooling/warming effect of wind, humidity and full direct sunshine to give an apparent temperature.
EVAPO-TRANSPIRATION is drying effect due to sun and wind, and is equivalent to "negative rainfall"

   DAILY STATS JULY 2009
 
TEMPERATURE ºc
HUMIDITY
SUN ‡
PRESSURE
RAINFALL
WIND SPEED
DIRECTION
  WEATHER
 NOTES ‡
DATE
Low
(21-09h)
High
(09-21h)
Temp at 14.00z
RH %
at 14.00z
Dewpoint ºc
at 14.00z
Bright
sun hrs
hPa   †
at 14.00z
Day Total
(mm)
Average
(mph)
Max Gust
(mph)
Dominant
(Compass)
  Precipitation
 type etc ‡
                       
1st
 15.1 29.8 29.3 33 11.4 9.7 1021.4 FS 0.0 0.8 11 SE  Sunny
2nd
 14.8 31.3 30.5 38 14.6 8.2 1015.5 F 0.0 0.9 12 SE  Sunny
3rd
 17.3 24.3 22.9 59 14.5 3.5 1012.0 FS 5.1 2.6 17 SW  Rain am, cloudy
4th
 13.7 24.7 24.6 39 9.7 7.7 1012.3 FS 0.0 1.8 13 SW  Sunny pm
5th
 15.6 24.2 23.6 48 11.9 8.3 1009.2 FS 1.0 2.8 19 SW  Rain am, sunny
6th
 14.1 19.4 18.7 63 11.5 4.8 1004.0 F 7.1 4.5 24 SW  Rain showers
7th
 13.9 20.6 20.3 56 11.2 2.7 1002.5 RS 9.7 2.5 16 SW  Thunder, hail
8th
 11.8 20.4 20.1 56 11.1 2.0 1011.2 ST 1.8 1.4 10 WNW  Rain showers
9th
 11.1 19.4 18.3 43 5.5 2.3 1014.3 FS 0.0 2.1 17 N  Cloudy
10th
 9.9 21.1 19.9 39 5.6 5.7 1015.7 ST 0.0 2.6 17 SSW  Sunny am
11th
 14.1 19.2 17.7 78 13.8 0.3 1013.0 FS 2.0 2.5 16 SW  Rain night
12th
 14.2 22.4 22.3 55 12.8 7.8 1006.9 RS 2.0 3.7 22 SW  Rain am
13th
 12.2 22.7 22.2 41 8.3 8.8 1008.6 FS 0.0 2.9 16 SW  Sunny
14th
 14.8 22.8 21.8 44 9.0 5.2 1008.1 ST 1.8 2.9 20 SW  Rain eve.
15th
 14.4 20.5 19.8 63 12.6 4.2 1013.7 R 1.5 4.5 22 SW  Rain, showers am
16th
 12.1 24.0 23.2 47 11.2 5.7 1016.2 F 2.5 1.8 19 SW  Thunder eve.
17th
 15.0 18.4 16.8 77 12.8 2.8 1002.8 FS 6.3 2.5 20 SW  Rain showers
18th
 12.6 20.8 20.7 50 9.9 5.2 1009.6 FS 0.3 3.8 21 SW  Rain shower pm
19th
 11.8 19.1 18.4 58 10.0 2.5 1010.8 FS 1.0 4.9 26 SW  Rain shower am
20th
 12.0 20.8 19.7 54 10.1 4.8 1014.8 ST 0.0 3.2 18 SW  Sunny am
21st
 14.6 24.2 20.7 63 13.4 2.2 1004.9 ST 1.3 2.0 16 SW  Cloudy
22nd
 14.5 21.1 20.2 56 11.2 3.3 1003.2 RS 0.8 4.0 21 SW  Rain shower eve.
23rd
 13.6 21.6 20.7 57 11.8 5.8 1003.8 RS 0.0 3.4 20 SW  Sunny pm
24th
 13.2 20.0 20.0 57 11.2 4.8 1009.8 ST 7.4 3.9 20 SW  Thunder pm
25th
 11.5 22.8 22.1 54 12.4 6.3 1021.8 RS 0.0 2.4 14 SW  Sunny spells
26th
 11.8 21.6 19.6 58 11.1 3.8 1016.3 FS 0.0 2.4 20 SW  Cloudy
27th
 12.5 19.4 19.0 65 12.3 3.0 1011.2 RS 5.1 2.6 20 SW  Rain am
28th
 11.8 21.1 20.5 52 10.3 6.3 1017.3 FS 0.0 2.8 18 SW  Sunny periods
29th
 14.3 21.9 21.1 53 11.2 3.7 1010.9 FS 4.8 2.2 20 SW  Rain Sh eve.
30th
 11.5 19.6 16.4 74 11.7 6.0 1019.6 RS 2.5 0.4 8 SW  Sunny periods
31st
 11.1 22.0 21.3 42 7.9 7.2 1019.0 F 0.0 1.1 14 SW  Sunny
                         
‡ SUN: Sunshine hours are calculated approximately and solely from solar radiation readings, but note that the solar sensor's exposure to sunshine is rather limited. The sensor receives approx 65% of total possible sunshine exposure this month, and there is no allowance for sunshine by visual observation only, so the figures above can be very significantly less than the actual daily sunshine duration.
† Barometer trend (previous 3 hours) : F = falling, ST = steady, R = rising; Q = quickly, S = slowly†
‡ Weather Notes use METAR codes: OVC = overcast; SHRA = rain showers; '+' = heavy; CAVOK = no cloud below 5000 ft & visibility> 10 km & no fog, precipitation or snow; SN = snow; RASN = Rain and snow