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Optimus Prime

December 2009 Statistics

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A fairly straightforward month in terms of weather. A fairly cold first day or so then mild and fairly unsettled spell until the 11st when it become cooler. Then progressively much colder and snowy until the 26th when temperatures returned to more normal levels at night although daytime temperatures remained on the low side.

It was coldest December since 1996. Although fairly close in proximity to 2008 and 2001. 2008 being marginally the 2nd coldest.

Mean Maxima 5.5c - 2.0c below normal

Mean Minima 1.0c - 1.6c below normal

Mean 3.2c - -1.8c

Rainfall total 100.3

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Firstly, no I'm not December Statisticslaugh.gif

Secondly, does anyone have the stats for Scotland? I'd imagine eastern Scotland in particular might've seen one of the coldest Decembers in a pretty long time.

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Sorry about the title error I did try and fix it but it won't let you edit the title. From climate-uk;

NScotland; 1.0-c

EScotland; 2.8-c

WScotland; 2.4-c

CScotland; 2.7-c

Overall about 2.2c below normal.

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Here, in snowy Great Asby, it's been a remarkable month for several reasons. The length of lying snow; from 17th through to the end of the month with three inches still in the garden as I type, and snow falling on eleven separate days. There were twenty separate air frosts (including the lowest temperature for 4 years), and two true ice days. The monthly mean temperature is also the lowest I have recorded in my twelve years of record keeping, and below the average December mean by a massive 1.6C.

The raw statistics are:-

Average daily maximum; 4.0C

Highest daily maximum; 10.5C (6th)

Lowest daily maximum; -0.1C (18th & 28th)

Average daily minimum; -1.4C

Highest daily minimum; 5.6C (6th)

Lowest daily minimum; -10.4C (20th)

MEAN TEMPERATURE; 1.3C (12yr average 2.9C)

Total rainfall; 92mm

Wettest day; 16.2mm (5th & 6th)

Highest wind gust; 36mph (7th)

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thats pretty impressive OON-mine show it the coldest since i started reporting the weather as an amateur (January 1997) and the 13 th coldest, using my stats and those of RAF Finningley in almost 70 years.

details later when I'm sober!

Happy New Year everyone

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Well the snow statistics for Shrewsbury are interesting because as:

Snow falling 7

Snow Lying 1

Max depth 1cm on day 24

They are EXACTLY the same as that other great letdown of a month, February 2005 :bomb:

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dec 2009

warmest day 11.8C on the 5th

highest min 6.5C on the 9th

coldest day 0.9C on the 23rd

coldest night -6.3C on the 19th

had some snow, 30 minute blizzard on 17th gave a covering

around 2 cm's on 23rd

snow on ground xmas eve and xmas day

3 hours of snow on the evening of 29th, all gone by 30th

not bad for nowadays

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Average Maximum Temperature : 4.9ºC (40.8ºF)

Average Minimum Temperature : 0.3ºC (32.5ºF)

Mean Temperature (Max+Min/2): 2.6ºC (36.7ºF)

High Temperature : 11.1ºC (52.0ºF) 6th

Low Temperature : -6.8ºC (19.8ºF) 22nd

Days above 20ºC : 0 Days

Days below 0ºC : 14 Days

Monthly Rainfall : 56 mm

Rain Days >1mm : 17 Days

Snow cover at 9am : 15 Days

Maximum snow depth 9am : 10.5cm 24th

Maximum Wind Gust : 38 mph 30th

Monthly Summary

A very cold month by the standards of this decade. Well below average, the mean temperature of 2.6ºC being a hefty 1.6ºC colder than the 71-00 Durham mean of 4.2ºC, and 2.1ºC colder than the Newton Aycliffe 5 year rolling average of 4.7ºC – obviously this month will bring the 6 year rolling average down! The warmest day of 11.1ºC was the only day to reach double figures and it is also the coldest maximum temperature recorded in any December at this station. The coldest minimum of -6.8ºC was also a cold record for this station. The rainfall total of 56mm was around average compared to the 71-00 Durham mean, but slightly more than the Newton Aycliffe 5 year rolling average of 42.2mm. Another record to fall was air frosts – this is when the temperature falls below 0ºC – this happened on 14 days.

But perhaps the most remarkable or memorable event of December 2009 as well as the persistant cold, was snow. The Met Office definition of a lying snow day is a day where snow covers more than 50% of the ground at 9am in the morning. For record keeping purposes I use the same standard and starting on the 17th with a dusting of snow until the 31st when there was still frozen snow on the ground, albeit broken cover at 9am, December had 15 consecutive days of lying snow on the ground. This is also a record and it is unusual to say the least for snow cover to last so long, especially considering the maximum recorded average depth was an unremarkable 10.5cm. A combination of persistant cold near or below 0ºC, and also the low strength of the December sun helped the snow stay around so long. I am convinced that had this snow fallen in February, even if the temperature was as low, that the snow would have melted fully on 2 or 3 occasions during the spell, because of the stronger sun. Certainly for longevity, the snow picked the best time to arrive, around the winter equinox.

And let us not forget we had a proper white Christmas with good snow cover lying. Not only that but it managed to snow on Christmas Eve and also on Christmas Day evening!

Certainly in 6 years of recording (72 full months) this month was a bit special and memorable, easily the harshest winter month. I would personally put it near but not quite alongside the truly exceptional July 2006 which was memorable for different reasons, heat, drought and sunshine.

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December for Cantley

The coldest December since I started my own statistics in January 1997. Only 2001 at 3.8C mean is close.

I had snow falling on 6 days and lying at 0900 (by Met O definition=covering more than half the ground) on 8 occasions.

Mean temp=3.5C (4.6)

Avge Max=5.8C (6.9)

Avge Min=1.2C (2.3)

Days with rain=13, but amounts at 0.2mm are uncertain due snow/frost

1.0mm or more is more certain at 10

Total rainfall=31.4mm

Days with snow=6 and lying snow=8 (partial cover on 5 other days-for Doncaster, although never more than 2cm and often < 1cm these figures are quite rare in ANY winter month)

Air frost=12 (10)

Ground frost=16 (15)

Fog 3 mornings and no thunder

I checked the RAF Finningley data as I have the full data sheets and this December is the coldest since 1992 (3.3C) although 1995, the airfield had closed by then MAY have been as cold possibly colder.

Using the Finningley data and my own gives a cover over almost 70 years and this is the 13th coldest recorded. Only 3 others in the past 30 years were colder with 1981 topping it with a mean of -0.5C

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2nd coldest month since I started recording in Dec 2004, beaten only by Jan 2009.

Max temp...11.6c

Min temp...-7.0c

Mean temp...2.5c

Lowest max...0.3c

Highest min...6.1c

Frosts...17 (most frosts in a month I have ever recorded)


Days of snow falling...4

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Hedon, East Yorkshire.

December 2009

Warmest Max: 10.5°C (on 06/12/09) - Lowest since 1995

Coldest Max: -0.1°C (on 20/12/09)

Warmest Min: 5.8°C (on 09/12/09) - Lowest on record

Coldest Min: -5.9°C (on 20/12/09) - Lowest since 1995

Average Max: 4.8°C (-2.8°C Below 1971-2000 Average)

Average Min: 0.8°C (-1.7°C Below 1971-2000 Average) - Lowest on record

Overall Average: 2.8°C (-2.3°C Below 1971-2000 Average)

Rain: 93.7mm (180% Of Normal)

Wettest Day: 14th (17.0mm)

Air Frosts: 10

Days with Snow: 6

Snow lying at 0900: 8 days

Dry Days: 5

Wet Days: 26

Days With Rain >1.0mm: 18

Thunderstorms: 0

A remarkable month. The mean temperature was the lowest of any month since February 1996 and the coldest in December since 1995. The month also had the lowest high maximum on record, the lowest high minimum on record and lowest average min on record (all back to 1982). The month alone was snowier than any single whole winter since 1995/96 (2000/01 was closest with 7 days).

It was also a month of two halves. The first 15 days were changeable and close to average with a mean of 5.0°C. Rainfall was common and only the 1st recorded an air frost. Despite this, temperatures were never very mild. Only the 6th recorded a double figure maxima and only two days recorded minima above 5°C.

It then turned much colder in the second half. The mean temperature was just 0.7°C. After the 14th the temperature failed to reach 5°C for the remainder of the month and only on two days was the minima above 1°C. There was a heavy snowfall on the 19th which remained on the ground for a week and nine air frosts were recorded. Perhaps the most notable day was the 20th which was an ice day, the first since 2005. The minimum on the morning was -5.9°C, making it the coldest since 27th December 1995.

Certainly a very special month.

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Monthly Weather Report for Garioch Weather Station, Inverurie, December 2009

Very cold and wintry, weeks 3 and 4, but drier overall.

Mean Temperature: 1.4°C, 2.3°C lower than the Long Term Average (LTA) of 3.7°C

Minimum Temperature: -10.0°C, on the 22nd.

Mean Minimum Temperature: -1.5°C, 3.2°C lower than the 1.7°C LTA.

Maximum Temperature: 9.4°C, on the 6th.

Mean Maximum Temperature: 3.9°C, 2.8°C lower than the 6.7°C LTA.

Maximum High Wind Speed: 31.0mph, on the 1st.

Total Rainfall: 48.8mm, 24.6mm lower than the 73.4mm LTA (66.5%).

Average Bright Sunshine Hours: 0.5hrs per day, 1.0hrs lower than the 1.5hrs per day LTA (32.0%).

For more detail, click here.

For 5 year comparison of key data, click here.

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For Warminster, Wiltshire ...

Average max = 5.29c (highest 11.6c on 6 Dec)

Average min = 1.46c (lowest -6.2c on 23 Dec)

Mean = 3.37c (not quite the coldest month of 2009 as Jan was 3.19c - that was in Westbury though)

Dry days = 9

Precip days = 22 of which wintry = 7

Rainfall = 87mm

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Not all that special here but still noteable compared to some decembers

Days of Lying snow - 6

Days of Snow falling - 8

Days of Sleet Falling - 8

Days of Ground frost - 4

Days of an air frost - 10

Last december was frostier however this december saw more snow here.

Was a very sunny month also and average to just below rainfall.

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Could not see one of these what with all the excitement with the cold and snow ongoing!

Llanwnnen December 2009 Summary and statistics


A rather cold start to Winter: unsettled with average rainfall. Sub zero mean minima; snow or sleet on 8 days; 13 air frosts.

1st: A brief cold and frosty start to the month, but the milder wet weather arrived later in the day.

2nd - 9th: Mostly mild and very unsettled and often wet (much like November really).

10th: A transitional day with high pressure on the scene at long last! Still mild but at least dry and sunny.

11th-16th: Mostly dry and settled but on the cold side with some frosty nights.

17th-24th: Winter arrived! A very cold and frosty spell leading up to Christmas with penetrating frosts. Down to -8c on both the 19th and 23rd. Sunny spells and some wintry showers and very icy, a thin covering of snow on the 21st and 22nd.

25th-27th: Less cold and unsettled with rain or showers, heavy at times.

29th-31st: Cold again, still unsettled with a wintry mix of rain, sleet and some snow at times. Biting easterly wind.


Total rainfall: 145mm= about average

Wettest day: 17.3mm 5th

Rain days >0.2mm: 22

Wet days >1.0mm: 19

Days of heavy rain >10mm: 6

Mean temperature: 2.8c

Mean Max: 5.9c

Mean Min: -0.3c

High max: 11.2c 5th

Low max: 1.1c 18th

High min: 7.0c 9th

Low min: -8.0c 19th

Air frost: 13

Ground frost: 22

Mean pressure: 1005mbar

Max pressure: 1032mbar 12th

Min pressure: 982mbar 22nd

Mean RH: 94%

High RH: 98% various

Low RH: 75% 18th

Predominant wind directions SSE

Mean windspeed: 1.1mph

Days with:

Hail: 4 or more (likely a day or 2 more while we were away Christmas - New Year)

Sleet or snow: 8

Snow lying 0900: 2

Gale: 0

Thunder: 0/1 (I think thunder was reported locally just after Christmas one day we were away)

Fog: 0

Fog at 0900: 0

post-2595-12630593308942_thumb.jpg post-2595-12630593601742_thumb.jpg

Note: Add 18 mbar to pressure figures on the graph

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