Monthly Archives: January 2015

Anemometer

Our anemometer appears to have started to work again. It certainly wasn’t us out there at midnight when it started up again! I believe that we have an intermittent fault in our ISS, the main processor, which will probably need replacing. Fingers crossed that it continues to function in the mean time.

Amemometer Problems -Again!

Unfortunately our anemometer decided to “give up the ghost” at 00.20  last night during a spell of sustained winds peaking at 72mph. While it is still in situ and there is no visible reason why it should have stopped recording, this is the second time this has occured, the last time being December 2011 also during strong winds. The equipment we use, a Davis Vantage Pro2, is a scientific instument and meant to be more robust than it is actually proving to be, this being the third major fault in 4 years, the other being a faulty temperature sensor.

2014 – Weather Summary

2014 was both nationally and globally the warmest year on record! This means that 14 of the 15 warmest years have all occurred in the 21st century! Here in the UK, the Met Office UK data series dates back to 1910, but it was also the warmest on record in the Central England Temperature (CET) series, which goes back to 1659 and is the longest instrumental temperature series in the world.

Record warm years are frequently associated with the temporary warming influence of the climate system known as El Niño. El Niño occurs when warmer than average sea surface temperatures in the eastern tropical Pacific combine, in a self-reinforcing loop, with atmospheric pressure systems. This can affect global weather patterns. Worryingly, the high global temperatures in 2014 occurred in the absence of a full El Niño. During the year, sea surface temperatures rose nearly to El Niño thresholds but this wasn’t accompanied by an atmospheric response.

Rising temperatures do not mean that we will be enjoying a Mediterranean style climate any time soon. Increased winds and rainfall are the more likely consequence, as was experienced here in the UK earlier in the year when 12 major Atlantic storms battered the UK bringing nearly double the usual rainfall.

The weather here at Askernish reflected the national trends with it being our warmest year to date, the average temperature for the year being 10.2°C . This is 0.5°C above the ten year average (2001 – 2010) and above the average for the past 4 years (2011 – 2014) by the same amount. Temperatures remained higher than average throughout the year with the months of May, June, July and September all  being the warmest on record here at Askernish, with July being the warmest month ever with an average temperature of 15.3°C. During July temperatures rose to 27.7°C, on the 24th, a new station record, along with Heat Index (28.7°C) and Apparent Temperature (29.3°C). The 24th also produced the highest daily temperature range, that of 14.3°C and the highest ever minimum temperature of 16.2°C was recorded on the 19th. Monthly record highs also occurred in March (15.5°C), June (22.1°C), September (21.7°C) and October (16.8°C).

These higher temperatures meant that there were only 2 air frosts recorded (when temperatures fall to 0°C or lower) during the year, the minimum temperature being -1.2 °C recorded on the 27th December. This is most unusual as the 10 year average is 18 air frosts per annum.

In character with increased temperatures, it was also our wettest year on record with 1121.4mm of rain falling during the year. As March began, it signalled the end of the metrological winter which is defined as December to February. According to Met Office figures, it was the wettest winter on record (records began in 1910) for England and Wales, and possibly the wettest for over 150 years. During the 3 months defined as winter which consists of 89 days, a total of 493.6mm of rain fell here in Askernish, some 62% above the 10 year average. There were only 2 days when rainfall was NOT recorded when our longest ever spell of wet weather finally came to end.  With no rain falling on the 28th January, it hailed the end of 61 consecutive days with recorded rain during which time 331.4mm fell here in Askernish.

The remainder of the year seemed to fare no better with the months of January (159.4mm), February (151.8mm), March (84.0mm), July (66.8mm), October (154.8mm) and November (123.2mm) experiencing their highest monthly rainfall ever recorded here at Askernish. In complete contrast, June (35.0mm) and September (19.6mm) were the driest, the later being the lowest monthly rainfall to be recorded here.

Winds were slightly above the 4 year average (2011-2014) with an average speed of 10.8mph, a wind run of 94,898.9 miles and 4 gale days occurring during the year. The predominant direction was SSW. Winds varied throughout the year with the months of February,  March, August and November being the windiest on record here at Askernish, while September and November were the calmest. Record high  gusts were recorded for the months of March (56mph), July (40mph) and August (50mph).

The arrival of a “weather bomb” in December meant that we experienced some extreme wind conditions with several days of consistently strong winds. These winds peaked on the 9th and 10th of December with a station record wind run of 740.6 miles on the 9th only for it to be exceeded on the 10th. On this day the average wind speed was 33.7mph which resulted in a wind run of 790.0 miles.

Statistical summary for 2014

Temperature (°C):
Mean (1 minute) 10.2                                                     –           highest annual Mean (1 min)
Mean (min+max) 10.3                                                    –           highest annual Mean (min+max)
Mean Minimum 7.7                                                         –           highest annual Mean Minimum
Mean Maximum 12.8                                                      –           highest annual Mean maximum
Minimum -1.2                           27th December           –           highest annual Minimum
Maximum 27.7                          24th July                       –           Station Record High Temperature
Highest Minimum 16.2           18th July
Lowest Maximum 2.7              27th December
Air frosts 2                                                                         –           Least air frosts to occur in a year
Days above 20˚C 15
Days above 15˚C 119                                                      –           highest number recorded in a year
Days below 0˚C 2                                                            –           lowest number recorded in a year
Days below -5˚C 0

Rainfall (mm):
Total for year 1121.4                                                       –           Station Record Annual Rainfall
Wettest day 26.8                       5th October
High rain rate 91.4                 18th October
Rain days 272
Dry days 93
Days >= 0.2mm – 272
Days >= 2.0mm – 164
Days>= 20.0mm – 2

Wind (mph):
Highest Gust 69.0                26th January
Average Speed 10.8
Wind Run 94898.9 miles
Gale days 4
Predominant Direction SSW

Pressure (mb):
Maximum 1037.22           28th December
Minimum 950.53                8th February

Days with snow falling 1
Days with snow lying at 0900 0

Total hours of sunshine 1077.0
Number of sunshine days 272

December 2014 – Summary

The weather throughout December was much as we have come to expect, wet and windy, although the weather bomb will be the enduring memory.

“Weather bomb” is an American term which seems to have been adopted here for a meteorological phenomena known as a rapid or explosive cyclogenesis . This is where dry air from the stratosphere flows into an area of low pressure. This causes air within the depression to rise very quickly and increases its rotation, which in turn deepens the pressure and creates a more vigorous storm. The definition of a weather bomb is an intense low pressure system with a central pressure that falls 24 millibars in a 24-hour period. The one that influenced our weather fell a staggering 50 millibars during that period!

The resultant winds that hit our shores on the 9th and 10th were impressive, not because of their peak gusts, but because of their consistency. Winds peaked at 69mph on the 9th and the wind run for that day was 720.6 miles, a station record which stood for only one day. On the 10th, winds averaged 33.7mph which produced a daily wind run of 795.0 miles, both new station records despite the peak gust only being 65mph.

Some brighter and calmer weather occurred during the festive season which resulted in the first air frost of the year (when the air temperature falls below 0°C) when temperatures fell to -1.2°C overnight on the 27th.

Despite the bright calm weather towards the end of the month, rain was recorded on every day of the month, something that has occurred 3 times in December in the past 4 years.

Statistical Summary for December 2014

Temperature (°C):
Mean (1 minute) 6.5
Mean (min+max) 6.1
Mean Minimum 3.9
Mean Maximum 8.4
Minimum -1.2        –        27th
Maximum 11 – 6th
Highest Minimum 8.3       –        31st
Lowest Maximum 2.7        –        27th
Air frosts 2

Rainfall (mm):
Total for month 132.4
Wettest day 9.8        –       9th
High rain rate 40.6        –        6th
Rain days 31
Dry days 0
Days >= 0.2mm     31
Days >= 2.0mm     26
Days >= 20.0mm     0

Wind (mph):
Highest Gust 69.0        –        9th
Average Speed 15.5
Wind Run 11491.0 miles
Gale days 1

Pressure (mb):
Maximum 1037.22        –        28th
Minimum 986.83        –        11th

Days with snow falling 0
Days with snow lying at 0900 0

Total hours of sunshine 34.2
Number of Sunshine days 19