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JANUARY 2010 daily and monthly summary

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JANUARY 2010
February 2010

1st - 7th
1st, LP 1003 hPa centres E of Shetland and in southern North Sea, LP 989 hPa Gulf of Genoa, HP over Iceland and S Greenland. 3rd, LP 1017 hPa Denmark, LP 989 hPa WSW of Cornwall 18°W, HP 1025 hPa Switzerland, light snow shower am giving slight dusting, more light snow showers pm and evening tracking in from NE. 5th, LP SW England with occlusion brings some heavy snow after 21.00h for around two hours giving 5cm snow cover. 6th, LP 997 hPa Channel Islands, further intermittent snowfall from early morning through the day, more persistent from 11.00 to 15.30 and from 17.00 to 20.00 adding 2cm snow depth. 7th, filling LP moves SSE from E Anglia, bringing morning and evening snow showers separated by a long sunny spell.
8th - 13th
8th, HP 1036 hPa southern Norway, LP 990 hPa near Majorca, with light snow showers through the morning and evening. 9th, HP 1044 hPa Southern Norway & 1033 hPa NW Ireland, further heavy snow showers early am adding several cm to snow cover to a max depth of 13cm in undisturbed area, further outbreaks of snow pm and evening. 10th, warm front brings very slow thaw but accompanied by light snow showers through am and pm, snow depth down to max of 9cm. 11th, rather dull but dry, old snow depth down to 6cm by late pm. 12th, slight thaw continues, snow cover at 5.5cm. 13th, HP 1027 hPa S Norway/Sweden, LP 986 hPa NE of Azores at 20°W , LP 968 hPa S of Iceland, occlusion brings moderate snow from early morning to midday and extra accumulation of 4.5cm, total snow depth old and new = 10cm over grass, slight thaw later.
14th - 16th
14th, occlusion from south brings light rain through the morning from 3am to midday, hastening the thaw. 15th, mist and fog am, mainly dull, remaining snow cover now slushy and patchy, 1-2cm only. 16th, prolonged moderate rain am clears away last of the lying snow and ice. No visual observations from 17th to 23rd.
24th - 31st
24th, light rain after 10pm from occlusion with drizzle lasting into early morning of 25th, LP 1025 hPa Brittany, LP 986 hPa W of Iceland, HP 1031 hPa W of Spain, HP 1043 hPa Latvia, very dull sky. 26th, periods of hazy sunshine. 27th, LP 988 hPa S Sweden, HP 1043 hPa 50N 20W, light rain showers pm. 28th, light rain late evening onwards, through to morning of 29th, LP 990 hPa London area, LP 987 hPa North Sea with series of cold/warm/occluded fronts, LP 975 hPa Norwegian Sea, HP 1032 hPa slipping W 30W/50N. 30th, mainly sunny. 31st, precipitation from frost melt.


JANUARY 2010 MONTHLY SUMMARY
ACTUAL TEMPERATURE
 AVERAGE
 Daily Maximum
3.5
 ºC ( -3.7C )*
 Daily Minimum
0.0
 ºC ( -2.8C )*
 Daily Mean
1.64
 ºC ( c. -3.3C )
 EXTREMES
 High Maximum
8.3
 ºC ( 17th  )
 Low Minimum
-5.7
 ºC (   7th )
 Low Maximum
-0.3
 ºC (   8th )
 High Minimum
5.8
 ºC ( 22nd )
 
   
 Days with max => 10 °C
0
  ( -7 )*
 Days with max <0 °C (ice days)
1
  ( ±0 )*
 Days with air frost
17
  ( +7 )*
 
PRECIPITATION
 Monthly Total
43.3
 mm ( 57%)*
 Days with measurable precip
20
 Days ( +2 )*
   ...of which, days with >= 1.0 mm
12
 Days ( +2 )*
   ...and days with snowfall observed
9
 Days  
 Days with Snow Cover
10
 Days  
 Days with Thunder
0
 Days  
 RAIN RATE & EXTREMES
 High Rain Rate
7.4
 mm/hr ( 16th )
 High Rain Total in 1 day
8.4
 mm ( 16th )
 High Rain Total in 1 hour
2.5
 mm ( 16th, 10.30)
 EVAPO-TRANSPIRATION
 Total for month
8.2
 mm  
 High Total for 1 day
0.6
 mm ( 30th )
APPARENT TEMPERATURE
 Low Wind Chill
-7.0
 ºC ( 9th )
 DAVIS HEAT INDICES THW & THSW
 Low Temp/Hum/Wind Index
-5.8
 ºC ( 7th & 8th )
 High Temp/Hum/Wind Index
8.1
 ºC ( 17th )
 High Temp/Hum/Sun/Wind Index
11.6
 ºC ( 17th )
 
DEWPOINT & HUMIDITY
 High Dewpoint
6.3
 ºC ( 16th )
 Low Dewpoint
-7.8
 ºC (   7th )
 Average Dewpoint at 14h
0.1
 ºC  
 Low Relative Humidity
50
 % ( 27th )
 Average RH at 14h
82
 %  
WIND SPEED & DIRECTION
 Monthly Average
1.1
 mph  
 Windiest day (Average)
3.9
 mph (   9th )
 Highest Gust
24
 mph ( 16th )
 Dominant Direction
N
 ( 27% )
 
BAROMETER
 Monthly Mean
1013.9
 hPa  
 High Barometer
1040.5
 hPa ( 26th )
 Low Barometer
987.8
 hPa ( 29th )
SUNSHINE
 Max Sensor Exposure to direct sun
4
 hours/day (8 - 9 possible)
 Calculated Monthly Sunshine Hours
23.1
 hours  
 Estimated Actual Hours (approx)
54.0
 hours  
 Sunniest Day Measured
3.7
 hours ( 30th )
 Days with no sunshine
11
 Days  
 
FOG
 Number of Days with Fog
0
 Days  
NEW RECORDS SET THIS MONTH
 
* Comparisons to site averages since 1984.
‡ SUN:
Sunshine hours are calculated approximately and solely from solar radiation readings, but note that the solar sensor's exposure to sunshine in Midwinter is very limited. The sensor receives only up to 25 to 40% 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 JANUARY 2010
 
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
-0.5 2.4 2.4 71 -2.3 1.3 1004.6 RS 0.0 2.1 14 N  Sunny
2nd
-2.3 3.6 3.4 71 -1.4 1.2 1015.9 RS 0.0 1.3 12 SSW  Sunny
3rd
-1.6 1.6 1.1 84 -1.3 0.5 1021.6 FS 0.3 0.2 7 N  Snow showers
4th
-4.2 0.4 0.2 81 -2.7 1.5 1016.1 F 0.0 0.5 6 SSW  Sunny
5th
-5.2 0.4 0.4 84 -1.9 0.8 1001.7 F 2.8 0.0 6 SW  Snow night
6th
-1.4 0.3 0.2 90 -1.3 0.0 1001.8 RS 2.0 0.5 10 N  Snow
7th
-5.7 0.3 -0.9 81 -3.8 1.8 1008.7 ST 0.5 1.7 16 N  Snow showers
8th
-2.7 -0.3 -0.4 87 -2.3 1.0 1020.6 ST 0.5 1.5 12 N  Snow showers
9th
-3.2 0.4 -0.4 76 -4.2 0.5 1019.6 F 1.5 3.9 19 N  Snow showers
10th
-1.2 1.1 0.9 89 -0.7 0.0 1015.1 FS 0.3 1.4 17 N  Snow showers
11th
-0.7 0.8 0.7 84 -1.7 0.0 1017.9 FS 0.0 0.0 2 NE  Dull
12th
-0.5 1.2 0.9 81 -2.0 0.0 1004.8 F 0.0 0.9 19 SE  Dull
13th
-0.7 0.9 0.8 88 -1.0 0.2 999.2 FS 3.0 0.2 10 SE  Snow am
14th
-0.3 3.3 3.1 92 1.9 0.0 1003.3 RS 5.3 0.0 3 SE  Rain am
15th
0.4 4.9 4.8 93 3.8 0.2 1018.0 ST 0.0 0.9 12 SE  Dull
16th
3.8 7.6 5.8 91 4.5 0.0 1002.8 F 8.4 1.7 24 SE  Rain am
17th
0.2 8.3 8.2 75 4.0 2.3 1017.8 RS 2.8 1.6 12 SW  Sunny
18th
4.1 5.8 5.4 92 4.2 0.0 1023.7 FS 0.0 0.3 6 SW  Dull
19th
2.6 6.7 6.5 93 5.4 0.0 1019.5 F 0.0 0.4 16 SE  Dull
20th
2.3 2.8 2.2 87 0.2 0.0 1008.4 FS 2.5 1.2 14 SE  Snow/Rain pm
21st
1.4 4.6 4.3 78 0.8 1.7 1018.8 FS 0.0 0.0 10 NW  Sunny spells
22nd
5.8 7.2 7.1 91 5.7 0.0 1016.1 FS 3.6 1.8 16 SE  Rain
23rd
4.4 6.4 6.2 88 4.4 0.0 1018.5 FS 0.5 1.0 12 N  Rain am
24th
3.6 6.6 6.3 71 1.5 1.0 1022.7 FS 0.8 0.5 8 N  Rain night
25th
3.3 4.3 3.4 86 1.3 0.1 1030.4 RS 1.3 0.8 12 N  Rain am
26th
0.6 2.3 1.9 68 -3.4 2.0 1038.5 FS 0.0 1.3 13 N  Sunny pm
27th
-3.1 5.2 1.3 77 -2.3 0.5 1026.2 F 0.3 1.6 16 SW  Rain shower pm
28th
3.4 7.1 6.6 70 1.5 0.7 1010.1 F 2.0 1.5 11 WNW  Rain evening
29th
3.7 4.7 3.7 82 0.9 0.1 989.3 RS 4.6 2.8 21 N  Rain am
30th
-1.7 3.1 2.7 65 -3.2 3.7 999.9 RS 0.0 1.5 13 N  Sunny
31st
-3.3 3.2 3.1 68 -2.2 2.0 1003.9 FS 0.3 0.8 7 SSW  Sunny spells
                         
‡ 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 25% of total possible sunshine exposure for virtually all of 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