The morning of December 11, 2022, began cold after an overnight frost that saw temperatures fall to -5.3C. Freezing fog lasted through the day, coating everything in rime to set the stage for what was to be one of the most notable snowfalls in years.
Precipitation started just before 7pm with a mix of rain, ice pellets and wet snow, this soon turning to all snow within 10 minutes and settled fast.
By 9pm there was a good 6cm; Wanstead Park was soon transformed.
By midnight the snow had stopped, leaving a good 13cm out the back
Elsewhere there was a rare sighting of thundersnow in Billericay.
That’s not a statement that applies much, least of all the second week of January. But the current weather pattern has seen this town in the Highlands subject to the warming influence of the Atlantic, to a higher degree than London.
The above 850mb chart, typical of the past week, shows the warmer air aloft and the south of the UK seemingly cut off from outside influence.
Indeed, lack of solar heating at this time of year ensures that any thermal activity is minimal – with very little mixing of the boundary layers by day.
Wanstead Park, being a frost hollow, has seen this phenomena most days during the past week with this part of London markedly colder than elsewhere in the capital.
By the 16th the 7-day running mean at Aviemore was 2.4C higher than Wanstead!
The crux of the article is that certain weather types can repeat at the same time of year with one having a 100 per cent probability!
The Christmas storm singularity occurs in 84 per cent of years.
While 84 per cent certainly doesn’t mean ‘nailed on’, in the current set up of models being evenly spread between settled and stormy it can be safely guessed at this range that there will be unsettled weather around on the 25th. Whether it will affect the whole country remains uncertain.
The last big snorter of a Christmas storm I can remember in London was 2013. The entry for the 23rd into the 24th reads.
“Cloudy and breezy start grew steadily duller with rain just before noon. Rain grew heavier with some really strong gusts into evening culminating at 2am. Cloud at one point was 10kms thick. Three deaths related to weather.”
There was chaos nationwide with flooding and power cuts.
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.
Average (5.1C – 5.9C)
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.
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
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.
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.
What’s the most ridiculous omen for an England win in the European Championship final against Italy on Sunday? After hearing this on the radio this week I decided to try to find one.
Readers of this blog will know my theories of how the weather and big events seem to be tied together. So it is no surprise that I’ve indeed found one.
Last month, I wrote about summer washouts. The one last month that began on the 17th saw 28mm fall, possibly contributing to what was a dull spectacle; England’s 0-0 draw with Scotland at a rain-soaked Wembley.
While putting together the July list of washouts one of only six events since 1959 began on July 19th 1966. Over 20mm of rain fell, coinciding with England’s group game with France. The Three Lions won the tie thanks to a brace from Liverpool’s Roger Hunt. Days earlier they had been panned after a dull 0-0 draw with Uruguay. No-one, apart from Alf Ramsey, fancied our chances. Yet by the end of the month they were world champions.
So, in terms of football singularities, England’s is one title every 55 years? We’ll know by 11pm on Sunday.
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.
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.
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.
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.
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