Monthly Summary - December 2014

   After the previous very poor December's of 2012 and 2013, in comparison this December would have to be classed as 'decent', but in reality it was mixed and fairly typical of the month. The first half of the month was colder than average and although insignificant, it was 'wintry' during 7-13th. The period of 16th-23rd was then very mild and responsible for the month finishing warmer than average, the final week of the month returning to 'normal' or indeed just colder than average temperatures.

   Overall it really depended on where you live in Cumbria as to how to judge December as literally a few miles made a big difference in rainfall totals. Seemingly anything east of Penrith had below average rainfall and anything west and north, above average. However, everywhere was warmer than average and the eleventh month of the year to be so.

   MSLP of 1014.4 Mb was +2.3 Mb above average, slightly surprising with a strong south-westerly flow dominating, although that flow veered westerly in the colder interludes and winds of anything remotely easterly were totally absent.

   Overall a mean minimum of 1.19°c and a mean maximum of 7.15°c saw the temperature some 0.8°c above the 1981-2010 average, making it the warmest December since only last year, 2013. The highest maximum temperature recorded was 12.3°c (17th), the lowest minimum -4.9°c (6th).

   At Newton Rigg (Penrith) in a complete series back to 1952, a mean temperature of 4.2°c makes this December the joint 27th warmest, ie: 26 have been warmer, 36 colder and one had the same mean temperature.

   Rainfall of 92.9 mm (Crosby Ravensworth School 112.0 mm) made it the driest December since 2010 and here at Maulds Meaburn was 61.5% of average for 2007-13 and locally it was quite mixed. Below average (80-90%) in our corner of Cumbria, but well above at mountain sites (Seathwaite 197.8%) and further north and west. At Newton Rigg (114.2 mm - Met' Office gauge) in a series back to 1914, thirty December's have been wetter (3 year of incomplete data).

   Figures from the Environment Agency’s rainfall sites were, (figure in brackets being the monthly average for 1961-90)   ‘Data kindly provided by the Hydrometry and Telemetry team of the Environment Agency (Penrith)’:

   Kirkby Thore 60.2 mm (71.7 mm)

   Brothers Water 424.4 mm (304 mm)

   Nunwick Hall 63.6 mm (78.3 mm) and

   670.6 mm at Seathwaite Farm (Borrowdale - 339 mm).

 

  1st - 5th    After sitting within a slack pressure gradient on the 1st that gave a misty and damp day, high pressure (HP) then ridged in from the Atlantic, that ridge becoming stronger (rising to 1029.0 Mb) and consequently the days were dry and settled. It also became calm and cooler both by day and night with the 4th at 4.5°c the first day of the season not to attain 5°.

   We also enjoyed plenty of sunshine during this period and even a cold front passing west-east during the 5th failed to produce any rain.

 

  6th    Still just under the influence of the now weak ridge of HP, the day started with a hard frost and a years low of -4.9°c (23.2°f). But that HP would collapse as a frontal system from the west swept across the UK and which brought some rain from 1600 Hrs and overnight into the 7th.

 

  7th - 11th    During this period and beyond the weather would be influenced by the 'Azores' high sat slightly further north and LP systems near Iceland that maintaining a northerly latitude. This gave a brisk westerly flow that brought cooler air and the days became wintry in nature. Troughs circulating within the flow saw the winds back NW'ly at times and it certainly felt wintry with some hail on the 7th and waking to a light dusting of snow on the 8th. But it remained bright with sunny spells.

   An advancing frontal system associated to a deep area of low pressure (LP) south-west of Iceland brought heavy rain (21.7 mm) and strong winds (gusting to 51 Mph) on the afternoon of the 9th.

   And once those fronts cleared the UK we fell back into a brisk westerly flow that brought showery conditions mainly of a wintry nature. Hail showers persisted throughout the day on the 11th and then a LP system to our south-west, tracking north-east and just skirting the bottom half of Cumbria, brought snow overnight into the 12th that gave a thin cover on the ground.

 

  13th - 15th    A weak ridge of HP turned the 13th cold and calm, dipping down to -4.6°c at the start of the day, but again ahead of a new depression arriving off the Atlantic later in the day. This brought light patchy rain preceded by snow, the rain becoming heavier overnight into the 14th.

   A series of rain bearing fronts brought rain during the 14th (Sunday) with the 15th having a mix of a sun and showers.

 

  16th - 27th    It then turned milder with some notably high day-time temperatures and it also remained generally unsettled. For the eight days of 16th-23rd the mean temperature was 8.2°c which is more typical of late April!

   The 16th remained cool and bright in a slack pressure gradient and weak westerly flow before a warm front connected to LP west of Iceland introduced cloudier skies and then rain.

   Milder air was also introduced and the 17th saw the mercury rise to 12.3°c (54.1°f), a new December high for this site. The 18th also topped 12° and whilst the 19-20th saw a dip to 7°c after a pair of cold fronts introduced cooler air and a brighter day on the 20th, the temperature then rose again on the 21st.

   Temperatures were fluctuating both by day and night and some of the days (16th and 20th-22nd) actually saw the days maximum temperature fall after dark. The 20th was the best day in the period, albeit somewhat windy as a strong westerly flow built over the top of HP to our south, but despite the presence of weather fronts on most days rainfall totals remained insignificant.

   This then changed as a long waving front connected to both LP in the low Atlantic, stretching across the UK to Scandinavia and back to LP near Iceland, tracked south east out of Scotland and became semi static over the north of England. The 21st was mainly a damp day of drizzle, becoming windy in the evening with 8.3 mm (10.9 mm at Crosby Ravensworth School) of rain falling overnight into the 22nd. But despite the presence of the frontal system rainfall was light and patchy with the main belts of rain to the north of the county. This is best illustrated at Seathwaite Farm which saw 104 mm fall on the 22nd and the three day period of 21st-23rd recorded an impressive 256.2 mm.

   The frontal system finally cleared south on the 24th bringing cooler air behind and Christmas Day was generally cloudy but bright with a light north-westerly flow. HP centred over Spain slowly began to nudge north, broadening out and extending over the UK and subsequently temperatures started to slip back to normal.

   A LP system to the west filled and tracked over the Midlands on the 26th, giving them several inches of snow, but beyond its northerly edge the 26-27th were fairly grey and murky. The 27th was also quite calm with a slight north-westerly flow, subsequently chilly and the month's coldest day at 2.9°c (37.2°f).

 

  28th - 31st    A large area of HP (1041 Mb) then built from our west and became established over the UK. This brought dry and settled conditions, but also night-time frosts with -4.0°c recorded on the 29th. The days were chilly but calm and both the 28-29th enjoyed plenty of sunshine and were really quite agreeable days.

   The HP began to slip east on the 31st allowing a cold front in the Atlantic, followed by an occlusion to progress east. The temperature slowly rose during the day and a dull day slowly became wetter, although the majority of the 10.7 mm of rain fell in the evening.

 

   Rainfall totalled 92.9 mm for the month, with rain recorded on 22 days of which 16 were 'Wet days' (1.0mm +).

   The Mean Temperature for the month was 4.17°c      --      The Mean Max' was   7.15°c     --      The Mean Min'   1.19°c.

   We had 10 Air Frosts in the month (year 26)                  --      Grass frosts totalled 20 (year 89).

   The 1 foot soil temp ranged from a low of 4.0°c on the 31st        to      a high of 8.0°c on the 2nd     --      with a monthly mean of 5.9°c

   The 1 meter soil temp ranged from a low of 7.2°c on the 16-18th     to      a high of 9.2°c on the 2nd - 3rd     --     with a monthly mean of 7.9°c

 

COMPARISONS:-

   * December 2014 rainfall was 61.5% of the December average for 2007 - 2013

   * December 2014 was 1.51°c warmer than the December average for 2009 - 2013 and 0.8°c warmer than the local long term average 1981-2010



* 2014 TEMP     9.58°c -- RAIN   1343.8 mm

* 2013 TEMP'     8.49°c -- RAIN   1232.1 mm

* 2012 TEMP'     8.26°c -- RAIN   1415.9 mm

* 2011 TEMP'     9.17°c -- RAIN   1305.4 mm

* 2010 TEMP'     7.42°c -- RAIN    702.9 mm

* 2009 TEMP'     8.86°c -- RAIN   1264.5 mm

* 2008 TEMP'     -- RAIN   1381.3 mm

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   © Darren Rogers 2014

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