The mean temperature for winter 2017/18 is looking average overall with average precipitation. While that doesn’t sound exciting for anyone looking for colder weather and snow I think the figures mask frequent 3 or 4 day-long cold snaps from the Arctic interspersed with milder interludes from Atlantic incursions; typical characteristics of a pattern driven by the troposphere. For anything longer term we have to hope for a warming of the stratosphere, a sudden stratospheric warming over the Arctic, that downwells into the troposphere, reversing the general westerly circulation. We are overdue an ‘SSW’ event but, even if one were to happen, its effects wouldn’t be felt until much later in the winter.
Figures generated using QBO statistics in the run up to December were identical to the outcome of 5C. It is figures generated using ENSO statistics, however, that produced the best results considering December, January and February alone.
It would seem that the winter was most influenced by the ENSO variable up until February when the effects of the SSW were enough to overcome it?
A few years ago I devised a winter index to try to decipher how modern winters ranked against legendary seasons, such as 1947 and 1963.
With the media hyping conditions last week, which were severe in many parts of the country, it is very difficult for many to gauge just how conditions compare with previous winters.
My findings show that this winter so far stands 27th. It is possible that further snowfall that results in lying snow at 9am between now and April will boost the position higher though, given recent years, this would seem unlikely.
Last week’s cold spell, while containing some impressive statistics, is put into perspective when it is compared with other severe spells since 1960. A decent cold spell but no record breaker in the form of a 1962/63.
Perhaps it is the advent of social media, the plethora of constant updates of the latest feet-deep snowdrifts and instant tales of heroism in the face of icy adversity, that has made this cold spell seem far more severe than it actually was in the minds of many; February / March 2018 was the first truly social media-driven cold spell.
The winter of 2017/18 will probably be remembered as much colder that it actually was – the exceptionally severe spell right at the end was only at its halfway point by the time the meteorological winter was over.
The mean temperature for the season finished 5C, that’s 0.5C below average and the coldest for five years.
Rainfall was above average: 180.8mm fell, that’s 124 per cent of average and the wettest for four years.
Sunshine was just over average: 174.4 hrs is 104 per cent over average and the sunniest for tree years.
As so often with winters at this latitude the average for three months makes it look a non-descript season – it is only when you look at the detail that compelling facts emerge.
The coldest day of the season occurred on the last day of February when the maximum failed to rise above -1C, the first ‘ice day’ for five years and the coldest day since 2010. It was also the seventh equal coldest February day in a local record going back to 1959.
The coldest night of the winter was in the early hours of the 28th when a low of -6.9C was recorded. The temperature would have been far lower were it not for a shower that moved in at 3am.
The warmest day of the winter occurred on December 30th with 14.2C recorded. The warmest night was on January 28th when the temperature fell to just 10.8C.
The wettest day of the winter occurred on January 2nd when 15.3mm was recorded.
Snow arrived at the start of winter and at the very end: seven days of snow falling and four days of snow lying over the three months is below average.
There were 30 air frosts during the three months, eight above the 1981-2010 average.
There were 11,680 minutes of frost over the winter, less than last year, though 66 per cent of those were recorded in February. Considering the past 6 Februaries this year’s frost hours were 170 per cent greater than the next highest, February 2016!.
Mean (1 minute) 5.2
Mean (min+max) 5.0
Mean Minimum 2.0
Mean Maximum 8.0
Minimum -6.9 on 27/02/2018
Maximum 14.2 on 30/12/2017
Highest Minimum 10.8 on 28/01/2018
Lowest Maximum -1.0 on 28/02/2018
Air frosts 30
Total for period 182.2
Wettest day 15.3 on 02/01/2018
High rain rate 28.2 day 02/01/2018
Rain days 52
Dry days 38
Highest Gust 45.0 on 02/01/2018
Average Speed 3.7
Wind Run 8059.5 miles
Gale days 0
Maximum 1036.4 on 22/12/2017
Minimum 970.3 on 10/12/2017
Days with snow falling 7
Days with snow lying at 0900 4
I’ve put together a few top 10s of stats for Wanstead, St James’s Park and Heathrow for the month of March.
The month, the first of the meteorological spring can offer really contrasting weather; perishing cold and very pleasant warmth are both very possible, as the values show.
Probably most notable in the list is the cold March of 1962 which was the coldest of the 20th century and 11th coldest in a local list going back to 1797. March 2013 was also very cold. Strong winds from deep depressions often feature as does the odd blizzard.
Marches in the 1960s also appear to often start very cold and end very warm; the term ‘In like a lion, out like a lamb’ being very appropriate.
•Though this blog only covers extremes back to 1959, thanks to Met Office digitised data, I’ve unearthed records prior to this. Both W.A.L Marshall’s A Century of London Weather (covering 1841 to 1941) and J. H. Brazell’s London Weather (covering 1841 to 1964) confirm the coldest March day as the 13th in 1845 when 25F (-3.9C) was recorded at Greenwich.
The coldest March minimum was 4/5 in 1909 with 9F (-12.8C) at Epsom. Greenwich and Hampstead recorded 14F (-10C)
January 2017 was a wet month. Just over 64mm of rain was recorded, 121 per cent of average, slightly less than last January.
The monthly mean finished 6.4C, 1.2C above average and the mildest January for four years.
Some 44 hours of sunshine were recorded, 88 per cent of average, the dullest January for six years.
The most notable event was during the early hours of the 18th when the ‘storm with no name’ felled many mature trees across a swathe of England, including a large beech on Blake Hall Road that led to the closure of the road during morning rush hour.
I’ve put together a few top 10s of stats for Wanstead, St James’s Park and Heathrow for the month of February.
Probably most notable is the cold February of 1991 which saw the deepest snowfall I can remember – days of snow saw the level depth past my knee in suburban London. February 1986 was also very cold but also very dry with little snow.
Februaries in the 1990s were also often warm with 19.7C being reached in Wanstead on 13th in 1998.
It is a shame that the Met Office only publishes easy to access daily data in Excel format back to 1959 as this obviously omits the classic snowy February of 1947 which is worth a blog on its own.
My winter forecast for the London area can be found here.
Some national UK February values according to TORRO
I’ve put together a few top 10s of stats for Wanstead, St James’s Park and Heathrow for the month of January.
Probably most notable is just how impressive the depth of cold was during the cold spell of 1987. When considering St James’s Park the temperature on the 12th never rose above -6C: nearly 4C colder than any January day in 1963, the coldest winter in modern times.
My winter forecast for the London area can be found here.
Some national UK January values according to TORRO
I’ve seen this phrase uttered more than once over the past couple of days thanks to high temperatures and humidity. But ask anyone to define a hot day and you’ll get a different answer every time.
Growing up in the 1970s / 80s redtop newspapers would use the phrase once the mercury was nudging 80F (26.7C). But to ‘scorch’ you need sunshine, preferably at least 10 hours of it. Considering statistics from the Heathrow airport climate station in west London there have been 463 scorchers since 1959, the most recent happening on July 5th with 29.5C recorded and 13.9 hours of sunshine. There have now been 9 scorchers this year, already matching the number that were recorded in 2014 and only 3 short of last year.
But even with last month’s heatwave this year has some way to go, however, to match the amount measured in 1976 and 1995: 31 days!