Tag Archives: London

UK rainfall: Seathwaite / Honister v London

February 14, 2024 wansteadmeteo Leave a comment

It’s been a wet winter so far. Some 177mm has fallen in Wanstead – already 122 per cent more what falls in an average winter.

But the amount pales into comparison with the Lake District. Since December 1st 1360mm has fallen at Honister, a station close to Seathwaite which proudly proclaims itself as ‘England’s wettest place’.

Over a calendar year the area usually sees 5.6 times the amount of rainfall of London. However, this winter the total of 1360mm makes it 7.7 times wetter! A testament to just how persistent the SW’ly airstreams have been this season. And a reminder that the Lake District is the called the Lake District for a reason.

Data from the excellent Starlings Roost Weather.

Climate of London, London weather, UK climatology

Rolling 12-month maxima in Wanstead, east London

June 10, 2023 wansteadmeteo Leave a comment

The rolling 12-month average maxima anomaly in Wanstead on June 10th is sitting at 1.6C.

Considering local statistics back to 1959 the figure reached an all-time high of 2.1C last November, a level it stayed until December 11th, when a very remarkable week of snow and frost arrived.

With unremarkable maxima for most of this year the figure has been falling. But with a building El Nino it remains to be seen if the highest anomaly ever of 2.1C will be breached.

Date	12-month rolling anomaly
10/6/2023	1.6
10/6/2022	1.1
10/6/2021	0.4
10/6/2020	1.3
10/6/2019	1.7
10/6/2018	0.5
10/6/2017	1.2
10/6/2016	0.9
10/6/2015	1.0
10/6/2014	1.4
10/6/2013	-1.3

Christmas Day weather

‘White flakes falling on the city brown’

December 3, 2022 wansteadmeteo Leave a comment

Written in 1890 this poem was composed when white Christmases were far more common.

LONDON SNOW by Robert Bridges

When men were all asleep the snow came flying,

In large white flakes falling on the city brown,

Stealthily and perpetually settling and loosely lying,

Hushing the latest traffic of the drowsy town;

Deadening, muffling, stifling its murmurs failing;

Lazily and incessantly floating down and down:

Silently sifting and veiling road, roof and railing;

Hiding difference, making unevenness even,

Into angles and crevices softly drifting and sailing.

All night it fell, and when full inches seven

It lay in the depth of its uncompacted brightness;

The clouds blew off from a high and frosty heaven;

And all woke earlier for the unaccustomed brightness

Of the winter dawning, the strange unheavenly glare:

The eye marveled–marveled at the dazzling whiteness;

The ear hearkened to the stillness of the solemn air;

No sound of wheel rumbling nor of foot falling,

And the busy morning cries came thin and spare.

Then boys I heard, as they went to school, calling,

They gathered up the crystal manna to freeze

Their tongues with tasting, their hands with snowballing;

Or rioted in a drift, plunging up to the knees;

Or peering up from under the white-mossed wonder,

“O look at the trees!” they cried, “O look at the trees!”

With lessened load a few carts creak and blunder,

Following along the white deserted way,

A country company long dispersed asunder:

When now already the sun, in pale display

Standing by Paul’s high dome, spread forth below

His sparkling beams, and awoke the stir of the day.

For now doors open, and war is waged with the snow;

And trains of somber men, past tale of number

Tread long brown paths, as toward their toil they go:

But even for them awhile no cares encumber

Their minds diverted; the daily word is unspoken,

The daily thoughts of labour and sorrow slumber

At the sight of the beauty that greets them, for the charm they have broken.

UK climatology, Weather

A chilly and dry autumn on the way?

August 20, 2022 wansteadmeteo Leave a comment

Anomalies of the past two months throw up some interesting singularities as we head into late summer and autumn – with a hint that we could be heading for a much colder than normal December.

Using stats from the past 60 days revealed the following years. Those most similar to the current ENSO situation are highlighted in bold.

The most negative month on average will be December.

In terms of rainfall those hoping for a deluge look likely to be disappointed, at least in the south-east, with a continuation of synoptic conditions that favour drier than average weather.

The best chance for a wetter than average month appears to be September though, given recent synoptics, this is likely more a result of trough disruption than any sustained period of Atlantic-driven fronts.

Forecast, London weather, UK climatology, Weather, weather pattern, Winter forecast

London Winter Forecast 2021/22

December 3, 2021 wansteadmeteo Leave a comment

This winter is most likely to be on the colder side of average with near normal rainfall.

While the modelled prognosis for the first half of December looks unsettled with an Atlantic influence evolving from the current chilly NW’ly to a mild SW’ly, local analogues of the climate of London suggest the season could be a bit of a rollercoaster with spells of wet, windy and mild weather alternating with dry, calm and cold.

A large factor to consider this winter is the presence of a slight La Nina that is forecast to evolve cooler.

Given the uncertainties involved with the influence of ENSO I’ve decided to stick with analogues found in local data that stretches back to 1797.

Overall then the probabilities for the next 90 days are.

Mean	Probability	Rainfall	Probability
Mild (>5.9C)	14%	Wet (>178mm)	19%
Average (5.1C – 5.9C)	38%	Average (107-177mm)	62%
Cold (<5.1C)	48%	Dry (>107mm)	19%

The above table doesn’t reveal a great deal in that extremes can be hidden in a month or season that finishes broadly average. So I decided to look closer at the winters that were revealed in the analogues.

December

The first month, as already mentioned, looks like it will be on the mild side with possibly a notable storm off the Atlantic before things calm down over Christmas – the period between Boxing Day and New Year’s Eve possibly presenting the best chance of any lying snow in this region.

The below graphs are a smoothed representation of the years revealed in the analogues most similar to this autumn.

What is probably most interesting is that the analogues that shared a similar ENSO / La Nina index to this autumn tended to ‘turbo charge’ any yo-yoing in the weather type, be that super-mild or abnormal cold.

December probabilties for maxima:
Mild: 48%
Average: 19%
Cold: 33%

And precipitation.
Wet: 33%
Average: 29%
Dry: 38%

So, the month overall will be mild and slightly dry

January

The first month of 2022 probably represents this region’s best chance of lying snow this winter. A mild start perhaps with a falling off of temperatures in the final third of the month and a cold spell of a week or so. As with December the influence of La Nina could tend to boost the swings in the pattern.

January probabilties for maxima:
Mild: 33%
Average: 10%
Cold: 57%

And precipitation.
Wet: 19%
Average: 43%
Dry: 38%

Greatest chances for January, then, are cold with average precipitation.

February

The second month may see a slight return of the cold spell in January before temperatures recover for a mild and wet spell in the second half.

February probabilities for maxima.
Mild: 33%
Average: 15%
Cold: 52%

And precipitation.
Wet: 38%
Average: 38%
Dry: 24%

The stats suggest on the cold side overall with average to above average rainfall. Perhaps the depth of the cold skewing any very mild second half of the month?

The extremes that no-one can forecast

As well as the very mild winter of 1989/90 the analogues also revealed the very cold winter of 1978/79. There were others but their occurence makes the probability of a repeat at either extreme at less than 10 per cent.

London weather, Rainfall, singularities, UK rainfall, Wanstead Park history, weather pattern

Four June washouts in london

June 23, 2021 wansteadmeteo Leave a comment

Compiling a list of sunless, rainy days revealed some interesting spells of wet weather – the most miserable runs of June days in the capital since 1959.

First up was a three-day spell starting on June 25, 1974. Some 34.3mm of rain was recorded.

Next was a three-day spell starting on June 23, 1991. Some 26.3mm of rain was recorded.

Another three-day spell started on June 25, 1997. Some 36.2mm of rain was recorded.

Finally, and most recently, a two-day spell this month that began on June 17th. Some 28mm of rain was recorded.

The above spells all happened around the date of the ‘June monsoon’ singularity which has a probability of 77 per cent. Though the fact that these occurred 47 years, 30 years and 24 years ago shows that these extreme cases happen a lot less than three years in every four the singularity would suggest.

Comparing the current Northern Hemisphere pattern with 1974 suggests that while there’s just as much heat around at 850mb as there was 47 years ago, including an extreme heatwave over some Nordic countries, the air above Greenland appears colder.

Rainfall, UK climatology, UK rainfall, Weather, weather pattern

Sunless days and washouts

June 21, 2021 wansteadmeteo Leave a comment

The weather of late has been in stark contrast to the mostly dry, sunny (if a bit chilly) spring many enjoyed. Indeed the first half of June saw more of the same and, locally, was the warmest start to the first meteorological summer month since at least 1959.

My memory of summers years ago was that it was often hot and sunny but I also remember countless days of staring out the window for hours waiting for relentless rain to let up.

Looking back at sunshine stats to 1959 there has been over 4,400 days where no sun was recorded, roughly a one in five chance of a totally cloudy day.

Considering the months where the absence of sun is most noticed, May to October inclusive, the probability decreases to just under one in ten.

To decant these to ‘washout days’ I’ve only included those sunless days that were also ‘wet days’ where 1mm or more of rain was recorded. The probability further decreases to just under one in twenty.

All very interesting but were there more washout days decades ago or is the memory playing tricks?

Looking overall shows an increase since 2013. Out of all the months the most notable change has been August.

London weather, Monthly Review, monthly summary, Wanstead Park history, Weather

Spring in Wanstead Park

June 6, 2021 wansteadmeteo Leave a comment

Spring in this neck of the woods was really mixed.

A chilly start to March became fairly benign before ending with the warmest March day locally since at least 1959.

April then turned much colder and drier; just 2.4mm of rain fell during the month – the driest April since 2007 and fourth driest in a local rainfall series back to 1797! Sunshine was abundant with over 200 hours. But clear skies at that time of year, with a polar continental airmass, often means air frost. And the ten recorded overnight was far higher than normal.

May saw things warm up slightly but the month still finished a degree colder than average. Some 80mm of rain fell which is over one and a half times what we’d normally expect. The wettest May since 2007 – the month playing catch up on the total absence of April showers that bring the spring flowers! It was a dull month with only 126 hours of sunshine, 69 per cent of average – the dullest since 1990 was third dullest back to 1881.

In terms of flora and fauna the colder weather played havoc with the trees, bud burst coming much later than recent years. As I write this on June 6th some of the later budders like false acacia have only just come into full leaf. The birds, as they normally do, just seem to get on with it raising their young. I’m not sure what the food supply has been like but judging by the amount of healthy juvenile fledglings I’ve seen I would guess that it has been a good season so far?

Here’s the stats.
March 8C (+0.3) 30.9mm (76%) 90.9 hours (84%)24.1C on 30th (a record that had stood since 1965)
April 7.2C (-2.6) 2.4mm (5.5%) 202.6 hours (127%)
10 air frosts in April, much higher than normal
May 12.1 (-1) 80mm (156%) 125.6hours (69%)
Spring 2021: Mean : 9.1C (1.1C below average, coldest since 2013, 111th coldest) Rain : 113mm (84% of average, wettest since 2018, 150th wettest ) Sun : 425.4 hrs (94% of average, dullest for three years. 51st dullest) The average masked extremes.

London weather, Seasonal summary, Weather, Winter forecast

Winter 2017/18 forecast review

March 5, 2018 wansteadmeteo Leave a comment

At the beginning of December the opening par for my forecast for winter read:

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?

Rainfall, Weather, weather pattern, weatherlore

The same old weather every year?

January 22, 2018 wansteadmeteo 2 Comments

Recurring weather patterns at certain times of the year are well known. The ‘Buchan Cold Spell’, ‘European Monsoon’ and Indian / St Martin’s Summer are all phenomena that have been studied extensively.

An article by the late meteorologist and broadcaster Philip Eden a number of years ago considered many of these patterns and found that, to varying degrees of reliability, they provided a guide to what the weather would be like at any given time of the year.

Considering climate change I wondered how much these patterns could still be relied on. Using my own pressure, rainfall and ‘wind run’ data (the total amount of daily wind) going back to the start of 2013 I had a look at the singularities for January and February

January patterns at the beginning, middle and end of the month appear to be the most reliable. However, it is only the ‘mid-Jan settled’ period that is most reliable.

Though this year’s ‘settled’ January spell saw rain the past 5 years have seen mostly dry weather.

windrun — Very little wind has been recorded around January 20th for the past 5 years

The early Feb settled spell occurs with very low probability: just 56 per cent. And this year the pressure, according to the GFS model, plotted below by WXCharts.eu, is predicted to be around 1040mb by February 2!

new gif — This animation of the GFS model shows the idea of the Iceland low, which drives our SW’ly type weather, ‘taking a holiday’ to southern Iberia, possibly advecting any cold weather in the east to flood the UK

Looking at the results of the past 5 years it could be concluded that the patterns do still occur but because of the nature of the jet stream, which seems to meander far more readily than in the past, these stormy / quiet episodes are becoming shorter than they were in previous studies.