weather bomb

2015 – Summary

With El Niño conditions developing very early in the year, it was almost certain that it would influence the weather, but it is never easy to say how or what its influence might be here in the Northern Hemisphere. As most weather models suggest when El Niño conditions exist, 2015 experienced the full range of extreme weather events around the world, most notably it being, globally, the warmest year ever with 2016 forecast to be warmer still! Whether this was entirely due to El Niño or by man-made influences is a continuing debate, but man-made global warming is now being thought of as the prime influence. Whether you are a believer in global warming or not, with these conditions continuing, they are set to influence our weather into next year.

Rising temperatures was a phenomenon that passed us by here in Askernish. For us, 2015 was our windiest, wettest and dullest year. As the year progressed, a full range of monthly records tumbled with the more unwelcome easily outnumbering the more pleasant ones being broken. This contrast was best highlighted by the months of June which was our windiest, wettest, coldest and dullest on record compared with October which was our warmest. August was our driest but perversely had the most rain days to be recorded during that month. New monthly atmospheric pressure records both high and low also occurred throughout the year. These often pass unnoticed and are of little concern to most observers, but they too are an indication of changing weather patterns.

The persistent wind is what most people will remember about 2015. This awareness was heightened with the occurrence of another explosive cyclogenesis or “weather bomb” in December, and then the Met Office personalising the storms by naming them for the first time later in the year. What followed that decision was Abigail, Barney, Clodagh, Desmond, Eva and Frank, all of which occurred during the final two months of the year. All these storms resulted in strong winds and heavy rain ensuring that this was our windiest and wettest year.

Six of the twelve months, January, March, May, June, July and November were our windiest ever with these months experiencing their own record high wind speeds and wind gusts. There were 9 gale days during the year which is yet another record here at Askernish. There were 3 in January, 2 in March, our first ever in November and 3 in December, all of which (apart from December) are records for this station. The average wind speed for 2015 was 11.9 mph which produced a wind run in excess of 100,000 miles for the year for the very first time.

One exceptional respite from the winds occurred in October when the remnants of Hurricane Joaquin passed further south than expected and left us eerily becalmed for three days. During this period, with an average wind speed of 0.6 mph and a wind run of just 14.0 miles, the 16th October became our calmest ever day!

With the winds came the rain with March, June and July being our wettest on record. In total, 1152.2 mm of rain fell during the year on 291 rain days exceeding our previous record by 30.8mm set only last year. Again in complete contrast the months of October and August were the driest ever here in Askernish but there were 28 days in August when rain fell, a record high for that month. Another milestone occurred on the 14th December when no rain fell on that day making it our first dry December day since 26th December 2012!

With wind and rain, there is always the associated cloud which seemed to shroud our islands for long periods during the year. It was therefore no surprise that 2015 was our dullest year with the months of June, July, October and November setting their own records by being our dullest. In February there were 5 consecutive days when NO sunshine was recorded, yetanother station record. One bright spot, literally and contrary to the gloom, May was oursunniest on record.

Globally, 2015 was the warmest year ever but not here. January, May, June and July were our coldest ever and only October and December broke any records, both being our warmest. There
were only 4 days during the year when the temperature reached 20°C and 61 when it exceeded 15°C, the latter being the lowest ever recorded in a year. There were 7 days when snow fell during the year, a record annual high.

A summary of each and every month plus the four seasons precede this post on the blog.

Statistical Summary – 2015

Temperature (°C):
Mean (1 minute)         9.3
Mean (min+max)        9.3
Mean Minimum           6.8
Mean Maximum        11.7
Minimum                     -3.3       18th Jan
Maximum                    24.7      23rd Aug
Highest Minimum       13.5       30th Jun          Lowest recorded in a year
Lowest Maximum        2.8          3rd Feb
Days above  20˚C          4
Days above  15˚C        61                                 Lowest annual total
Days below  0˚C           11
Days below  -5˚C           0
Air frosts                         10

Rainfall (mm):
Total for year           1152.2                              Highest annual rainfall
Wettest day                22.6     5th May
High rain rate              67.0     9th Dec
Rain days                     291                              Highest number recorded in a year
Days >= 2.0mm            167                              Highest number recorded in a year
Days >= 10.0mm            26
Days>= 20.0mm               2
Dry days                         74                              Lowest number recorded in a year

Wind (mph):
Highest Gust                 76.0      8th Jan
Average Speed           11.9                            Highest annual average wind speed
Wind Run             105417.9 miles                   Highest annual wind run
Gale days                  9                                   Highest number recorded in a year

Pressure (mb):
Maximum             1043.65         7th Feb
Minimum                947.68        14th Jan

Days with snow falling                  7               Highest number recorded in a year
Days with snow lying at 0900      4

Total hours of sunshine           1011.0            Lowest annual total
Sunshine days                           265

January 2015 – Summary

The topsy turvy weather continued with this being the windiest and coldest January on record here at Askernish.

January will be yet another month remembered for the wind. The month started with fresh to strong winds but then a series of 3 deep depressions triggered by yet another explosive cyclogenesis (weather bomb), coupled with an exceptionally strong jet stream, influenced our weather from the 8th onwards. While we escaped the more severe winds that were experienced only a few miles further north, they peaked here at 76 mph early on the 9th, a record high for January, and continued until the 15th , during which time gusts of 50 – 62 mph occurred regularly. During this period, there were 3 gale days, another record for January. Winds eased from the 16th onwards but were still fresh to strong, gusting to 51 mph on the 27th and 28th . The total wind run for the month was 12,712 miles with an average speed of 17.1 mph, both record highs for the month of January.

Temperatures struggled during the month, especially with the strong winds drawing cold air down from the north throughout the month, resulting in the coldest January to be recorded here with a mean (1 minute) temperature of 5.5°C . A record low temperature for January of -3.3°C occurred on the 18th while there were also record lows for Wind Chill (-7.4°C) on the 16th, Apparent Temperature (-11.3°C) on 15th and Dew Point (-5.1°C) on 19th. Contrary to this, a record high temperature for January of 10.8°C occurred on the 9th during a relatively calm period when record high Heat index (10.8°C), Apparent Temperature (10.9°C) and Dew Point (10.3°C) also occurred.

Rainfall during the month was above average at 157.4 mm which is 39.0 mm above the 10 year average 2001-10 and 26.6 mm above the 5 year average 2011-15. There were 30 rain days during the month, another record for the month of January. Because of the low temperatures there was 1 day with snow lying and 5 days with snow falling, the latter being yet another record for the month of January.

Other measurements of note were the highest hourly rain rate of 6.6 mm during the height of the storms on the 9th, a low humidity of 50% on the 13th and a low pressure of 947.68 mb on the 15th, all records for the month of January.

Statistical Summary

Temperature (°C):
Mean (1 minute)              5.5                       – record low for the month of January
Mean (min+max)             5.2                       – record low for the month of January
Mean Minimum                2.7                        – record low for the month of January
Mean Maximum               7.7
Minimum                          -3.3       18th         – record low for the month of January
Maximum                        10.8         9th         – record high for the month of January
Highest Minimum            7.2        4th
Lowest Maximum            4.2       18th
Air frosts      3

Rainfall (mm):
Total for month      157.4
Wettest day               18.0         20th
High rain rate          62.2            8th
Rain days                  30                      –  highest number recorded in January
Dry days 1
Days >= 0.2mm  –   30         – highest number recorded in January
Days >= 2.0mm  –   23         – highest number recorded in January
Days>= 20.0mm –    0

Wind (mph):
Highest Gust      76.0     8th      – record high for the month of January
Average Speed    17.1                 – record high for the month of January
Wind Run     12712.0 miles      – record high for the month of January
Gale days        3                          – highest number recorded in January

Pressure (mb):
Maximum  1027.26    3rd
Minimum    947.68   14th    – record low for the month of January

Days with snow falling  5    – highest number recorded in January
Days with snow lying at 0900 1

Total hours of sunshine 31.7

Number of sunshine days 20

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

A short-lived record…

The “weather bomb” continued to exert its influence on our weather throughout yesterday resulting in another record breaking day! As forecast, the record high wind run of yesterday lasted just a day.

During the day (10th December), although winds only gusted to 65 mph, the average wind speed for the 24 hour period was 33.2 mph resulting in a wind run of 795.0 miles, both new record highs!

Winds are expected to ease slowly returning to what is considered “normal” for here by Saturday.

Our windiest day!

9th December 2014

With the arrival of the phenomenon known as a “Weather Bomb”, the 9th December 2014 proved to be our windiest day ever here at Askernish. The winds, although not as strong as sometimes experienced, they were of a consistent strength to produce a daily wind run of 740.6 miles.  Winds peaked at 69 mph during the night when wind speeds touched 45 mph but were not sustained long enough for it to register as a “Gale Day”.

With this weather bomb due to influence our weather for several more days yet and with increasing winds forecast for today, this record is likely to be short lived.

To learn more about weather bombs, visit the Met office website at: www.metoffice.gov.uk/learning/learn-about-the-weather/weather-phenomena/weather-bomb