Tag Archives: wanstead

Whatever happened to proper summer thunderstorms?

Is anyone else yearning for a good old-fashioned summer thunderstorm? As we move in to what is traditionally the most thunderstorm-prone month – the Met Office average for this area is three days of thunder – you would be forgiven for thinking that we have plenty to look forward to.

Looking north toward Aldersbrook. The Flats can be very exposed during a thunderstorm
Looking north toward Aldersbrook. Wanstead Flats, a 186 hectare open space that is larger than Hyde Park, can be very exposed during a thunderstorm

It was George II who some time during the 1730s apparently characterised the British summer by saying that it was ‘three fine days and a thunderstorm’.

The reality these days, at least in this part of the country, is quite different. Yes, brief fine spells do still break down – but the classic stormy nights I can remember being kept awake by when I was a lad in the Eighties are now a distant memory. A look back through the records shows that our most thundery month happened in June 1982, when thunder was heard on 13 days. On the 2nd a woman was killed after being struck by lightning while walking in a park in Willesden. More storms followed over the next couple of days and there were three more deaths in the UK caused by lightning. One thunderstorm over Loughton flooded 200 houses, some up to the ground-floor ceiling and at least 12 properties were struck by lightning. One observer recorded 79mm of rain, one and a half times the monthly average, in 90 minutes.

Despite a couple of instances of good potential for thunder this past month has been, so far, completely thunder-free, with all the activity passing well to our east. On June 20-21, there were 235,809 lightning strikes in 24hrs over Germany. To put that into perspective the UK, on a typical ‘thunder day’ in summer, receives up to 10,000 ground strikes although the exceptional day of 24 July 1994 produced 85,000 ground strikes.

The meteo is sited on the Aldersbrook Estate and uploads data to the web every 10 minutes, 24 hours a day
The meteo is sited on the Aldersbrook Estate and uploads data to the web every 10 minutes, 24 hours a day

So what is the potential for thunder in July? Looking back at Wanstead and the surrounding area’s local records the average number of days that thunder was recorded works out as 3.5 – though some years thunder occurred considerably more than others. But to get thunderstorms first we need the ingredients. The classic scenario happens at the end of a short heatwave, a cold front advancing from the west undercuts hot and humid air that has been in occupation for two or three days. If there is sufficient moisture in the upper atmosphere, cumulonimbus clouds will bubble upwards to the base of the stratosphere, and thunderstorms will soon follow.

Apart from the first couple of unsettled days at the beginning of July the above scenario looks unlikely to happen at least in the first half of the month. The North Atlantic Oscillation is predicted to stay positive into July – this spells good news for us as it suggests that the Azores high will dominate our weather, bringing lots of fine and dry conditions. With the jet stream and westerlies being kept just north of Scotland, temperatures should be average to slightly above. It is possible that the high could further dominate as the month goes on. But it is also possible that pressure will start to fall after around the middle of the month. Though it is impossible to predict in detail perhaps a date of around 20th would be the most likely for thunder?

It is too soon to say if the recent trend for a paucity of thunderstorms is just a blip. It could just be another typical variation of the British weather and we will shortly see an upturn in summer thunderstorm activity.

Scott Whitehead
@wanstead_meteo
wansteadweather.co.uk

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Wanstead Meteo Bulletin (Jan 17 – 23)

The next seven days look to be remaining cold, with a risk of snow at times. The temperature will struggle to get above freezing most days – maximums are likely to average 0.1c by the end of the week. Minimums are forecast to average -4.6C – so plenty of frost around again and some very low minima possible should any snow settle. Despite warnings to the contrary by the Met Office I am not expecting Friday / Saturday’s snow event to amount to much for our area – 5cm to 8cm at most – with all of the action well to the west of us and over high ground. There’s a chance that the front will fragment before reaching us – or even stalling over southern England before “pivoting” away into France. This scenario has happened many times before when we’ve had a “block” of very cold air to our east and north-east as we do now. Another event looks possible on Tuesday – but don’t be surprised if we see very little snow.

The past week, as discussed in the last bulletin, saw a change to progressively colder weather, the change being very marked last Wednesday with the appearance of the sun after days of cloud and gloom. The murk and cloud returned though it stayed cold, by Saturday with a chill east wind. Sunday failed to bring the predicted snow – the front just wasn’t powerful enough against the cold block to our east. However, Monday was different and snow began to fall around 5am on Monday, giving a 1cm covering. The track of the low saw a warm sector pass over up, raising the dew point and turning the snow to rain at low levels. Epping and areas of a similar height managed to remain snowy.

Mean temp: 1.2C; Mean min -0.8C (0.2c warmer than forecast), Mean max 3.1C (1.1c warmer than forecast),

lowest min -3.5C(15th), highest max 4.7C (3rd), total rain 3.9mm

4 air frosts

Wanstead Meteo Bulletin (Jan 10 – 16)

“The River Lea is now firmly frozen, and the Thames so much encumbered with ice that navigation is scarcely practible.”

Saturday (January 12) represents the 199th anniversary of this event noted by Luke Howard in “The Climate of London” – a pioneering book on the study of urban climate, which contained continuous daily observations on temperature, rainfall and wind direction. Temperatures the following week of the severe winter of 1813/14 at his laboratory in Plaistow, just a few miles from here, are hard to imagine by today’s standards in the capital – the average maximum being -2.2C, with night temperatures falling to an average -7.8C.

There has been much talk of severe weather arriving from this weekend onwards, with some chatrooms on the web ramping up rumours of a repeat of the severe winter of 1947. Whilst it is going to turn cold, with the possibility of snow increasing from early Sunday onwards, it is far too early to make predictions of a repeat of the famous ’47 winter which did not really get going until well into the second half of January. Indeed, records from Camden Square show that this week in 1947 would be remarkably mild – with a mean maximum of 10C while nights were a mild average of 5C.

So what has the next seven days got in store? With confidence in weather forecasting models at an unprecedentedly low level it is hard to pin down exact values on temperatures and weather much beyond Sunday. At the time of writing we can expect maximums to gradually creep downwards through the period – giving an average of 2C by the week’s end. Minimums are forecast to average -1C – so plenty of frost around. It currently looks like any precipitation on Saturday will start as rain before turning wintry. There is the chance this will turn to snow by Sunday morning to give a covering. Far more snow looks likely from Monday onwards. As said there is much uncertainty so keep a very close eye on output from the Met Office if you are planning on travelling.

The past week has seen much dull, cloudy and quiet weather, influenced by high pressure on the near continent. I often find this to be the worst possible winter weather as nothing much seems to happen. A bonus it did bring, however, was a break at last from all the rain.

Mean temp: 9.1C; Mean min 7.8C, Mean max 10.5C,

lowest min 5.9C(5th), highest max 11.7C (3rd), total rain 2.7mm

Pre-Christmas weather pattern

While things were wet in Wanstead the past couple of days the rainfall in our part of the UK was not really anything remarkable for December. Anyone who’s watched news reports the past couple of days would realise that it is the South West that has been taking a real hammering from incessant rainfall. One observer in Wembury, Devon, recorded a new high 24-hour rain total of 60.5 mm to 6pm, breaking a previous record set in August 1986.

The most notable thing in Wanstead on Saturday was the balmy ‘feel’ of the air which originated from the Caribbean at the beginning of the week. At 9pm the 13C ‘dew point’ made our part of the world the warmest anywhere at 50N or 50S. Almost summer-like and it seems the world has turned upside down. Weather stats for the Falkland Islands show that it is more like winter there than high summer.

I have been checking past years’ pre-Christmas rainfall, for the purpose of this study the 7-day period from 16th to 22nd inclusive.
This year is third wettest, beaten only by 1995 and 1989. So what does this mean for weather in the new year? Not much, probably, for anyone not a fan of weather forecasting by pattern matching. However, it is interesting to note the weather that followed these two wet Christmas periods… Both were very different.

Things turned very cold at the end of January / beginning of February 1996 – with an ‘ice day’ being recorded on January 26. Snowfall during the cold spell wasn’t really anything to write home about.

Anyone who follows the weather will remember that in January 1990 occured the devastating Burns’ Day storm that was responsible for the death of 97 people across the UK. The month as a whole, and February, was virtually frost free, stormy and very mild – positively balmy at times.

These two polar opposites just go to show that you forecast by pattern matching at your peril – though 1996 gives any coldies reading this hope for the new year.