Category Archives: UK climatology

Ben Nevis: a serious mountain

Strong winds, hail, sleet and snow were experienced in abundance when I climbed the UK’s highest mountain at the weekend. ben start

To give us a chance of making it to the 1,345m summit and back we left Fort William in darkness. Heavy rain that had greeted our arrival the previous day had abated but the spooky balminess of this early January remained; a local thermometer was reading 11C at 7am!

A gorgeous purple hue tinged the early morning dawn as we began our ascent though it was not long before the rain returned.

 

Proceeding upwards, after about an hour, we passed another climber who was walking down, having abandoned his attempt because of ‘atrocious conditions’. “I’m more of an ice and snow climber,” he explained, telling us how wonderful conditions had been in Zakopane, Poland, just a few days previous.

Unperturbed we pushed on soon making it to the tarn – the Lochan Meall an t’Suiche. We had ideas to climb the Ben via the Carn Mor Dearg arête but a wrong turn and conscious that time was not on our side we turned back and continued on the pony track / tourist route. Just over two hours in we passed the ford, just below which the route begins zig-zagging its way up to the summit.ben tarn

By now the rain started to get heavier. At around 900m it turned to hail. It was at this point that we passed another climber: “It’s snowing on the summit but you don’t need crampons,” he exclaimed before hurrying on down. We passed a further dozen or so walkers on our way to the summit; all of them looked like they couldn’t wait to get off the mountain. The rain was now a wintry mix of hail, sleet, snow and frozen rain – painful to walk into in the strengthening wind.

ben paul bothyAs the peak started to level out around 1,150m snow was now beginning to settle on the rime that had built up on the cairns; we’d got what we’d come for! It was here, however, that I realised my waterproof trousers weren’t so waterproof. First dampness then rivulets of water began flowing into my boots.

The peak was now well fogged in and for the first time I felt a bit uneasy, conscious of the fact that the wind was also still gathering strength. Regardless, my climbing pal continued to press on just ahead of me. Poor visibility concealed the summit which was still another 100m or so higher. Although he’d previously climbed the Ben (in perfect summer conditions) he’d forgotten exactly where the trig point was and was careful to observe the cornices to the side, so lethal to inexperienced walkers who fall through them every season.

We made a beeline for the bothy close to the trig point; my climbing partner, who was also trying to deal with waterlogged boots, was keen to change socks. At that point a gust of wind caught the bothy door – it smashed open leading to the rime that had built up on the hut to fall to the ground. I was starting to feel well out of my comfort zone and I persuaded him against the sock change, saying we needed to turn around and get down as quickly as possible. Despite both having crampons in our rucksacks I decided against spending more precious time trying to wrestle them on to our boots. Although the ground was coated in rime I knew that the warm front that was coming in was already lifting the temperature – and we’d cope without them.

ben paul trig

The route down was easier if unpleasant. Once we’d descended far enough out of the cloud and wind I knew we’d be OK and it was just a case of taking it steady over the uneven cobbles.

Night was fast drawing in by the time we arrived back at the Ben Nevis Visitor Centre. As we called a cab for the short drive back to Fort William all I could think about was a hot bath back at the hotel and a welcome pint by the fireside.

All around Fort William it is frequently mentioned that conditions at the top are totally different and that the Ben should not be under-estimated. As someone with nearly four decades of experience of being in and around mountains I should know better than most. But Ben Nevis is not just any mountain and deserves complete respect.

The meteorology of the climb

aonach
The temperature trace shows that the warm front arrived after 11am
aonach wind
The WSW wind was gusting F6/F7 giving a windchill of -5C and lower

* Despite the awful conditions I did manage to get a few photos, including the observatory where Victorian scientists lived for 20 years, gathering meteorological observations until 1904. Experiencing just a taste of the conditions that they would have had to endure makes their achievement all the more remarkable.
The observations have recently been fully collated and are providing valuable insight into the study of how mountain conditions have changed since that time.

** The following article was printed in the Lochaber News, 9th January, 2013

Stupidity can get you killed

The leader of Lochaber Mountain Rescue Team has issued a strongly-worded warning in the wake of a walker’s “act of sheer stupidity” in trying to tackle Ben Nevis in winter in trainers.

John Stevenson (58), who heads up Britain’s busiest mountain rescue unit, said a man rescued on Monday afternoon was fortunate to be alive after attempting the country’s highest peak without proper equipment for the conditions and time of year.

The 31-year-old walker was airlifted to hospital in Fort William after he fell while descending the 4,409ft, snow-covered Ben. He sustained a leg injury while walking on the main mountain track and managed to alert the police to his situation at about 4pm.

A full search and rescue operation was launched involving police, 18 mountain rescuers and a Royal Navy helicopter from HMS Gannet, Prestwick.

The injured man was located and airlifted from the Red Burn area, above Lochan Meall an t-Suidhe, and was treated at Belford Hospital for his injury and the effects of the cold.

Mr Stevenson said the incident could have turned to tragedy.

He said: “He’s an extremely lucky young man to have survived.”

“His equipment was just rubbish – he had nothing. He was wearing trainers and didn’t have a torch.”

“He did everything we tell people not to do. When we found him he’d lost one trainer, the backside was out of his trousers and he was wet and cold.”

“There’s no doubt in my mind that he would not have survived the night if he hadn’t phoned in on his mobile, and we were lucky enough to find him.”

“He didn’t actually set off on his ascent until 11am, having come straight off the train at Fort William. That’s just a ridiculous time to be starting out when darkness falls at about 4pm. It’s crazy and not on at all.”

“He made it to the summit okay but slipped on the way back down and managed to call the police on his mobile phone.”

Mr Stevenson added: “Initially he was on the so-called tourist path but he lost his way and veered off the path.”

“He slipped and hurt his leg but kept on walking – but realised he was lost and phoned the police.”

“He was talking to the police as he walked and then the phone just went dead. All the officer could hear was running water.”

“We had been alerted by this time and were on standby, so when the line cut out we all feared the worst.”

“I knew the only place on the top half where you can hear water running like that is the Red Burn, so we sent two members of the team up with the helicopter, as well as members on foot. Luckily the first two found the casualty pretty quickly. He had fallen but was okay. He’d lost his phone.”

Mr Stevenson said he found it increasingly frustrating that, despite annual messages from rescue teams, climbing organisations and the police, walkers were still heading to the mountains ill-equipped for the conditions.

“People need to be prepared,” he urged. “They need to heed the advice about having proper equipment and clothing.”

“The thing is, so many people get away with it every year, but unfortunately many don’t and end up injured – or worse.”

“The man on Monday was very lucky indeed and we could see he was extremely relieved to be off that mountain.”

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November 2018: average and rather sunny

November was most notable for the amount of sunshine. Some 79 hours were recorded, that’s 135 per cent of average, the sunniest November for two years.

The mean temperature finished 8.4C, 0.4C above average, the mildest November for three years.

Some 72.5mm of rainfall was recorded, 122 per cent of the 1981-2010 average, the wettest November for two years.

To view full stats follow this link:http://1drv.ms/1kiTuzv

november 2018

London winter forecast 2018-19

Long range modelled forecasts have been all over the place of late and, looking at the underlying signals, it is easy to see why.

When I’ve produced these forecast in the past, in terms of QBO and ENSO data, there’s usually a lot of analogues to compare with. This year, however, seems to be an exception.

Considering QBO first I looked back over data to 1950 and found nothing similar for October. However, looking over the whole series the cyclical nature of this circulation may give some clue.

bestfit

Some 20 months were revealed, ranging from June 1959 to June 2015.  Using NOAA’s  Niño 3.4 region I narrowed this list down to the few that had an ENSO value of around +1 with a rising trend. With NOAA’s forecast of a Modoki El Nino (one that occurs in the central Pacific) this narrowed the list to just 1 period: June 2015. Considering maxima anomalies this would give the following winter.

winter 2018-19 max anomaly.PNG

The above would suggest there being a general cool down through December with a cold spell starting just before Christmas into the new year? And another cold spell end of January into the first week of February?

winter 2018-19 precip anomaly

The above precipitation anomaly chart would suggest a wetter than average December,  January and February, though February by much less so.

It’s been a very busy autumn so I’m keeping this short.

The below figures, particularly January and February, may be different in the event of an SSW occurring. In all then.

The mean:
December: +0.8C
January: -1.2C
February: -1.7C
Overall: -0.3C (broadly average)

Precipitation:
December: 158%
January: 155%
February: 120%
Overall: 134%

 

How cold will November end?

Twitter and other forums have been at fever pitch with excitement for a ‘nailed-on’ cold spell. 

But with many getting carried away over tales of a repeat of March’s ‘Beast from the East’ it is important to remember that snow in November is extremely rare in the south-east; despite predictions of the incoming upper air being very cold the ground is still very warm and will take time to cool.

However, as seen in November 1993, a week of hard frosts were enough to chill the ground enough for a decent week-long cold spell. Similarly, although the snow didn’t arrive in London until December, November 2010 was also cold enough.

The weather of late has been in an ‘average mood’ with the mean temperature in September and October both finishing at 0.2C below. The mean for the this month is currently (on the 15th) running 1.8C above average, therefore for the mean to finish the same as September / October would require a big cool down, as hinted by the models.

Will we see another an average, 1993 or a 2010 end to the month. My hunch is it will be something between the three.

Below is a graph that shows this November so far with average, 1993 and 2010 ends.
2018: 0.4
1993: -0.8
2010: -1.4

East London’s highs and lows of the last 60 years

The chart below shows every maximum and minimum temperature recorded in this area since January 1st 1959, some 21,860 days!

The extremes range from -12.7C recorded on January 31st 1972 to 37.5C on August 10th 2003.

After peaking in 2003, summer maxima seems to be in decline. Winter minima, by comparison, has been increasing since 2012

maxmin

November: an Indian summer before turning cold?

With the mean temperature of both October and September finishing 0.2C below average it is probably safe to say that the weather is in an average kind of mood.

Conditions during the first part of November look changeable, according to the Met Office’s 30-day forecast . After mid month, however, the agency says the forecast is uncertain.

Now that much of the UK has had its first frost any warm spell in November will, correctly, be called an Indian summer. A singularity called the St Martin’s Summer occurs in 66 per cent of years, occurring between 15th and 21st and peaking on the 18th.

And, as if by magic, the GFS model today has this chart for the 16th, an Atlantic ridge of high pressure with daytime temperatures about 6C to 8C above average. Though warm during the day I would imagine there being a risk of fog forming at night

16th

Beyond that there could be a tendency for much more unsettled weather at the end of the month. The early December storms singularity occurs in 98 per cent of years, starting between November 24th and December 14th, often peaking on December 9th.

November, the last autumn month, can often surprise with its extremes, though it can also often be characterised by days of anticyclonic gloom. The warmest, coldest and wettest November conditions in London back to 1959 can be found here.

 

 

Perfectly average months are extremely rare

Readers of this blog know that I often described a month as fairly average – a look at local statistics shows that many months come in very close to the monthly mean.

But when you combine mean temperature with rainfall that is 100 per cent average it becomes very rare and non-existent with 100 per cent sunshine hours considered.

Of the 2650 months since 1797 just one, February 1972, saw a mean temperature and rainfall precisely average. However, sunshine hours were just 40 per cent of the 1981-2010 average.

To extend the data I included monthly rainfall totals that were between 90 per cent and 110 per cent of average. Even then just five more months were revealed: September 1806, February 1876, January 1883, October 1886 and March 1972.

Although on paper February 1972 was perfectly average a look at the weather for the month reveals typically variable weather. The website London Weather explains:

The maximum temperature was only 3C on the 1st as mild Atlantic air slowly displaced the very cold continental air eastwards. There were outbreaks of rain, and during the remainder of the first week, although mild, it was often dull and wet. During the second week, active frontal systems crossed the country bringing strong winds but with sunshine between the rain bands. After mid month, east winds returned, and although not cold, it was frequently dull.

Considering the Met Office forecast the mean for this month, October 2018, is set to finish precisely average. However, rainfall looks set to finish well under the average for the time of year.

London’s October extremes since 1959

October is one of those months that can see both ends of the spectrum; from calm ‘mists and mellow fruitfulness’ and, rarely, frost, to wet and wild systems whistling in off the Atlantic, best known being the 1987 Great Storm and, more recently, the St Jude storm.

I’ve put together a few top 10s of stats for Wanstead, St James’s Park and Heathrow for the month of October.

october extremes

October SJP

Heathrow oct

Some national UK October values according to TORRO

Hottest: 29.4C March, Cambs – 1st 1985
Coldest: -11C Dalwhinnie 28th 1948
Wettest: 208.3mm Loch Avoich 11th 1916

In terms of climatology October maxima, considering the 1981-2010 average, shows a decline through the month, though around the 8th and 20th there is often a spike. This would reflect the October singularities; early October storms, between 5th and 12th, peaking on the 9th, occur in 67 per cent of years. St Luke’s summer, between 16th and 20th, peaking on 19th, also has a 67 per cent probability.
Mid-autumn storms occur between 24th and 29th October, with a 100% probability.

october average graph

The average rainfall graphic shows that downpour amounts are variable through the month. A tendency for dry weather around the 17th and 18th before the wettest days on the 20th and 21st.

October rainfall

 

 

 

Wild equinox brings memories of childhood

Wild weather in the run up to the autumnal equinox was frequently a staple of the Septembers of my childhood but it has been absent in recent years.

Since 2013 I have been recording the ‘wind run’ data on my AWS, a stat generated by the amount of times the anemometer spins.

wind run

The results show there has been nearly two-and-a-half times more wind than the 5-year average.

Stormy weather over the equinox is one of the less frequent recurring singularities. The meteorologist Philip Eden a few years ago noted that ‘Mid-September storms’ during the period of 17th to 24th September had a frequency of 60 per cent.

20th
The wind run was the highest on 20th

When did September become a summer month?

The answer is around 1993. A look back at mean temperature and rainfall statistics for east London over the past hundred years reveals that the ninth month has, since that date, slowly become warmer and drier.

Putting all the arguments of meteorological and astronomical summer aside, many people of a certain age regard September as an autumnal month, but as recent years have shown it can very often be an extension of summer; September 2016 was the second warmest on record in the local area, warmer than many previous summer months!

Looking back even further, over the past 100 years, the September mean has trended upward, though many peaks and troughs reveal how the month has ebbed and flowed from being summery to autumnal.

The prognosis to the end of this month suggests that air pressure will be anomalously high – so the pattern in the south-east for settled, summery weather in September doesn’t look like ending any time soon.

sept means
The September mean trend has crept generally upward.

sept rainfall
A look at rainfall back over the last 100 years shows that wet Septembers have been on a general decline since 1994.

sept chart.gif