Tag Archives: wanstead

Pressure peaks and troughs

Air pressure is probably the least celebrated meteorological statistic, most probably because unless you’re staring at a barometer all day you can’t ‘see’ it.

High pressure brings mostly fine weather while low pressure usually brings wind and rain – though it is the gradient of the isobars that can measure the impact each system can bring.

Steep falls and rises in pressure bring the most memorable events, in my case the October 1987 storm.

During the next week there will be a notable fall in pressure – but how will it compare with the past recent years? Looking at my own stats, a relatively small but complete set of 9am barometer readings back to May 2013, it does look like it will be notable.

The table below shows the numbers to beat.

As with many of these events the most impactful weather was found in the north of Scotland. The first period coincides with Storm Caroline.
The Met Office blog says Caroline brought a max gust of 93mph at Fair Isle and transport disruption and closed schools across the Western Isles.

Of course what goes down also comes up and pressure rises can be even more notable. In February 2016 the pressure rose 50mb in just three days, a week or so after Storm Imogen.

According to the Met Office FAX charts the 9am pressure in London on March 11th will be around 988mb, which would represent a fall of 48.6mb from 9am on March 6th.

The early March storms singularity

Storms in late February / early March occur in 88 per cent of years, according to Philip Eden’s study on singularities.

This year looks no different although the drop in air pressure looks like it will happen just in the nick of time.

The GFS op for the March 9th compared with the situation on the 2nd

A look at the past eight years shows the effects of the pattern are quite pronounced.

And a look nationwide reveals the following named storms occurred around this period.

Storm Jake, March 2, 2016

Storm Ewan, February 28, 2017

Storm Emma, March 1, 2018

Storm Karine, March 2, 2020

And going back further reveals a notable storm in the 19th century.

Luke Howard’s meteors

Attention on the bright meteor seen over the UK earlier this week got me thinking about the meteors frequently mentioned in Luke Howard’s Climate of London volumes.

Howard had a keen interest in all things atmospheric, not least this celestial phenomena. Many of his personal accounts are mentioned over a period of a decade or so including accounts of meteors overseas.

April 4, 1807

February 1, 1808

July 12, 1808

December 16, 1808

March 22, 1809

May 1, 1809

July 18, 1809

January 26, 1811

April 1, 1811

November 7, 1812

April 23, 1813

July 29,1813

February 2, 1816

December 12, 1816

August 6, 1817

Decenber 8, 1817

January 28, 1818

February 6, 1818

Grimmest winter since 1979

The last three months in east London, considering sunshine, have been the dullest for 10 years. Despite the sunny end to February just 123 hours of sun have been recorded, just under 74 per cent of the seasonal average.

With little sun, rainfall well above average, temperatures best described as average and the endless lockdown it is no wonder things felt so grim.

A couple of years ago, inspired by the blogger XMetman, I devised my own ‘grim index’ to try to rank how each winter ‘felt’.

Using the same criteria, and assuming that most people welcome sunshine, it can be seen that since the least grim winter of 2007-08, the season, after a blip in 2018-19, has been growing steadily worse.

The grimmest winter, considering statistics back to 1881, was, ironically, the 1978-79 ‘Winter of Discontent’ when, again ironically, ‘Sunny Jim’ Callaghan was in Downing Street as widespread strikes coincided with the coldest winter for 16 years.

On looking at the Top 20 of grim winters it is striking how most coincide with depressing world events, the Great War, World War 2 and the Spanish Flu pandemic.

THE STORM OF MARCH 4, 1818

Early March often brings stormy weather, a singularity that has a probability of 88 per cent!

An example of just how long this singularity has been around can be found in the early 19th century

In his book The Climate of London Luke Howard mentions that the air pressure on March 4th was the lowest measured for some 37 years. The lowest point of 28.35 inches (960mb) is remarkable in that the lowest I’ve measured in Wanstead since 2012 was 969.8mb last December!

The storm brought devastation across a wide swath of southern England with loss of life on both land and sea.
Howard’s account of the storm mentions the barometer falling an inch in 15 hours with rain after dark with the wind “raging in violent gusts from SE and SW till past midnight when it abated after much thunder and lightning”.

His friend in Manchester, Dr William Henry, wrote a storm SW caused considerable damage, delaying the London mail in Macclesfield from 8pm until 3am on the 5th, the storm raging until 3am. The barometer fell to 28.2in (955mb) at Manchester.

Character of the period for the most part tempestuous with frequent rains the barometer running through a series of sharp depressions till near the close when it suddenly assumed the elevation of fair weather Almost all the showers from the first were more or less mingled with hail

Elsewhere in Britain public ledgers also reported the storm.

Yarmouth A most tremendous gale of wind from the S to the SE with rain came on about 8pm which continued with increasing violence all night and has done considerable damage to the shipping on this part of our coast.

Deal Last night it came on to blow a most tremendous gale from the south and continued nearly the whole of the night with unabated violence at midnight it blew a complete hurricane accompanied with thunder and lightning during which several vessels in docks suffered.

Portsmouth It blew a tremendous hurricane last night from S and SSE accompanied with the highest spring rides ever remembered.

Ryde One of the severest gales of wind that has been felt here for the last 37 years was experienced last night. It commenced about 4.30pm and continued with increased violence until past 11pm during which time the greater part of the pier and several houses were demolished. The supposed damage is estimated at between £4,000 and £5,000. No lives were lost nor any damage done to the shipping.

Dartmouth We experienced a perfect hurricane last night at SSE from 6pm to 10pm

Exmouth On the 4th instant between 7pm and 8pm we had a most tremendous gale of wind about SSE with dreadful rain thunder and lightning.

Falmouth At day light this morning the wind was from the WSW moderate. About 11am it strengthened to the S and from that to SSE and since that time until 10pm it has blown a hurricane with a heavy sea.

Penzance We had a very heavy gale here on Wednesday the 4th.

Milford On the 4th it blew a very heavy storm from SW to WNW.

Leicester Wednesday night was one of the most boisterous recollected for years past. Much damage has been sustained in this town and many parts of the county.

Hull At high water about 4.30pm the wind then blowing from the SW with moderate weather the tide flowed at the Old Dock Gates 18ft 6in. After the tide had fallen from 1 to 2in the dock gates closed as usual with the ebbing of the tide which then began again to flow to the height as near as can be calculated of four or five inches thereby opening the gates again and continued flowing. The tempestuous night of Wednesday ensued the wind blew a heavy gale still from the SW and at high water at 5am Thursday morning the tide was 14ft 1in being 4 feet 5 inches less than on the preceding evening although from the spring tides having put in the water ought according to the usual state of things to have flowed higher than on the Wednesday evening

Plymouth At the commencement of the winter a few large stones were placed by themselves on the top or finished part of the Breakwater to see if they would stand the winter gales they stood all but this last and this morning I found them washed from the top and lying on the North Slope There were three of them one of nine tons and the other two of five tons each they will be replaced as soon as possible for further trial Plymouth The effects of the late thunder storm of the 4th March on a fir tree belonging to W Langmead Esq at Elfordleigh in the neighbourhood of Plymouth are too singular to be omitted and perhaps the most extraordinary ones that ever occurred in this county on such an occasion The tree in question has been long admired for its size and noble proportions being more than 100 feet high and nearly 14 feet in girth but it exists no longer having been literally shivered to pieces by the electric fluid Some of the fragments lie 260 feet from the spot and others bestrew the ground in every direction presenting altogether a scene of desolated vegetation easier to be conceived than described.

The cold spell of February 2021

Valentines Day 2021 saw the cold spell come to an end in the London area. Maxima over the past 7 days never exceeded 2.3C on any day, the yardstick I use for a spell of cold weather to qualify.

Though some places did get a decent amount of snow precipitation in this area was very low ; lying snow at 9am at this station never exceeded 3cm. Very cold, dry air however was enough to preserve cover out of the sun.

As cold spells go it was two days longer than the median of 5 days, so slighter colder and drier but with double the amount of sunshine.

A couple of years ago I tried to rank cold spells in this area since 1960, with mixed results. I’ve since revisited the method and have achieved better results using the following algorithm.
(Number of days * total precipitation)*(mean temperature of spell)-(total sun hours). This gave the following list.

And the next 26 cold spells

A comparison of the upper air at the start of two cold spells

There’s been many images that define this spell but this post probably nails it in that I’ve never seen the ice thick enough on the marshes to tempt someone to ice skate.

The GFS Scottish Christmas Day blizzard of 2020

With the midnight run of this model bringing the start of the 25th into range the prognosis for the big day is a rare white one – for those north of the border.

The rest of the country is messy mix of sleet and, in London’s case, cold rain with a high of 7C. It looks fairly average for this locality!

The GFS operational chart for 0000 on the 25th

But followers of this blog and elsewhere will know that any model output beyond 72 hours should be taken with a very large pinch of salt.

But while conditions out to 15 days are often very different they can give a general guide to how the atmosphere is evolving in the medium range. The last few winters I’ve been doing this Christmas day model blog have revealed that conditions are sometimes not wildly different from what was hinted at 372 hours before.

Over the last few days the GFS, and other models, has been flip-flopping between cold and mild, a symptom of the current atmospheric situation which suggests that the polar vortex may undergo displacement as we progress further into winter. This could signal colder weather for NW Europe – but exactly where this colder weather will be as we progress to the end of the month is very uncertain – any colder than average weather could remain closer toward Central Europe, as happened in 2008.

Below are charts for each day from the midnight operational run of the GFS model.

London winter forecast 2020/21

The best chance for lying snow this winter looks like being at the end of the second week of January.

A combination of local analogues and global atmospheric factors including the El Niño-Southern Oscillation suggest that the coming season will be colder than recent years. Though that’s not saying much considering just how mild winters of the past decade have been.

Meteorological autumn was the warmest for 5 years and slightly drier than last year’s wet autumn. Though it shares some similarities with 2015 the external influences are thankfully different to that season which produced the warmest December on record. Considering data back to 1797 I was able to make the following suggestions on how the next 90 days may unfold.

December is most likely to be around average temperature-wise with rainfall also about average. Possibly stormy at the end of the first week. Any snowfall events are likely to be marginal – bad news for anywhere below 70m above sea level. In terms of Christmas a white one in London looks unlikely. There may be interest in the week running up to the big day but I wouldn’t be surprised to see that inexplicable warm up that often happens just as the 25th arrives.
Mean: 5.8°C (5.6°C 1981-2010 average)
Rainfall: 57.1mm (53.2mm 1981-2010 average)

January is the month most likely to see any lying snowfall, particularly during the first half of the month, with the mean temperature about 1C colder than average. Rainfall is likely to be above average.
Mean: 4.1°C (5.2°C 1981-2010 average)
Rainfall: 63.8mm (53.2mm 1981-2010 average)

February looks wet and mild overall.
Mean: 6°C (5.3°C 1981-2010 average)
Rainfall: 55.6mm (39.2mm 1981-2010 average)

Overall the mean for winter: 5.3°C, a little below average.
And rainfall about 120 per cent higher than average.

Looking in closer detail reveals that the coldest period is most likely to be between 13th and 19th January, with anomalies sufficiently low enough for lasting lying snow.

The extremes that no-one can forecast

As well as the extreme December 2015 the analogues also revealed the severe season of 1822-23 which saw ice on the Thames by late December. February 8th saw a great snowstorm in northern England where people had to tunnel through the snow.

Another was 1950-51 which was very snowy at high levels. There were 102 days of lying snow at Dalwhinnie (1000ft), exceeding the 83 days set in 1946-47. December 15th saw 15in of snow in Shanklin, Isle of Wight in 3.5 hours.

Hours of frost

Frost is a rare beast this year, even in the Wanstead Park frost hollow.

So far this year I’ve recorded just 82.5 hours where temperatures at 4ft (1.2m) were -0.1C or below. That’s just 37 per cent of what is recorded in an average year. And would suggest that frosts in December will be above average.

The lack of frost this year is even more remarkable given that the past seven years, especially the winters, have been so mild.

A closer look at the data shows that winter months are no guarantee of seeing temperatures fall below freezing. The record mild December 2015 and February 2014 are testament to that.

The fact that January 2017 looks the most remarkable month for frost reveals just how mild recent years have been.

Two warm April days 128 years apart

The synoptic pattern on Sunday, April 5th, was very similar to the pattern on Tuesday, April 5th 1892.

With so few planes in the sky because of the coronavirus lockdown it offered an ideal opportunity to compare temperatures and sunshine totals between now and then.

Sunday dawned sunny and clear and stayed that way until dusk, some 11 hours of sunshine recorded, exactly the same as 1892!

The temperature in Wanstead reached 22.3C, 0.9C cooler than what was recorded at the Royal Observatory, Greenwich, in 1892. This maximum was reached after an overnight minima of 5.3C, the same as the 41.5F recorded at Greenwich all those years ago.

Looking further afield, and at the spell over 3 days… markmpcc

4th

5thww

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