Archives for June 2010

Today marks the 3rd anniversary of the worst summer floods ever to hit Yorkshire.

Averaged over England and Wales, June 2007 turned out to be the wettest since 1860.

The period in June 2007 that brought severe flooding to large parts of Yorkshire was the wettest 12 day summer period ever recorded in the county.

Interestingly June 1982 was even wetter than June 2007. But in 1982, heavy downpours were more evenly spread throughout the month whereas in 2007 the rain was concentrated in a much shorter time period, resulting in flooding that was far worse and more widespread than anything experienced in 1982.

I visited Filey earlier this week. The Muston road area has suffered flooding 3 times in 8 years: In 2000, 2002 and 2007 localised torrential rainfall left sewers unable to cope, leading to flash flooding of local properties.

It's becoming a common problem. This part of Filey used to be agricultural land. But the need for new housing has lead to extensive development. So when torrential downpours occur, the rainwater runs off much more quickly than it used to do, leaving local sewers overwhelmed.

Up and down the country, urbanisation is leading to more and more incidents of flash flooding, and it's often too easy for the media to blame it on climate change. It's true to say that if climate projections are correct for the UK, a warmer climate will lead to heavier rainfall. But urbanisation is a significant factor in the increased incidents of localised flash flooding.

Yorkshire Water, who are ultimately responsible for surface water drainage think they have come up with a solution - in Filey at least.

They've spent over £2 million pounds building a flood water storage tank that holds 1.1 million litres of water - by volume its half the size of an Olympic swimming pool and is designed to hold excess water that the sewers can't cope with until the storm abates, slowly releasing the water back into the sewer system when the rain stops falling.

It's a fear that many people who have been flooded have; every time it rains, will it happen again? After 3 floods in 8 years, the residents will be hoping that the next time a downpour affects Filey, they can be a little more relaxed about the risks of 4th flash flood hitting Muston Road.

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UPDATED at 1pm Wed 7th July

Thanks to Quaesoveritas for highlighting the error in rainfall statistics. It has indeed been the driest start since 1953, not 1929.

ENDS

People in North West England are facing a hosepipe ban unless there's significant rainfall very soon, following the driest start to a year there since 1929.

But despite the geographical proximity to Yorkshire, according to Yorkshire Water, the situation here is much healthier. At the end of last week, water stocks were running at around 75%. So why, when we have had similar weather to Northwest England, are we not facing imminent drought orders here too?

This is because reservoirs aren't our only source of water - in fact this is where about ¾ of our drinking water comes from. The rest comes from bore holes in the East.

And the reservoirs in the West of our region are connected to the bore holes further East by an underground pipe network capable of pumping water from one part of Yorkshire to another.

And, if necessary, water can be pumped from some of the county's rivers, like the Ouse outside York, which are also connected to this underground pipe network.

This pipe network was laid as a direct result of the disastrous water shortage of 1995, which is still fresh in peoples' minds. Reservoirs were at healthy levels at the end of winter 1995, but a combination of a very dry Spring and Summer, coupled with a water pipe network that was in dire need of repair, meant that by the end of Summer the Nidderdale reservoirs, which supply water to Bradford, were within 10 days of running completely dry. Convoys of tankers brought millions of gallons water by road all the way from Northumberland to Scammonden reservoir in Calderdale in a desperate attempt to prevent stand pipes on the streets. It was a pr disaster for Yorkshire Water.

But it's thanks to the lessons learned by Yorkshire Water in 1995 that the county now has arguably the most reliable and robust water supply in the country. That said, if the dry weather continued into July and August, the authorities may come under pressure to follow the Northwest region in looking more closely at seeking a drought order.

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Rainfall across the UK has been well below average so far this year. In fact across the UK it's been the driest January to May since 1964. This is due to the almost complete absence of our usual rain bearing weather systems, which normally bring unsettled weather from the West.

Since December of last year, the atmosphere has been 'blocked', preventing the normal sequence of weather fronts moving across the UK. Instead, high pressure has been dominant, leading to a distinct lask of rainfall.

Although there is no sign that we are about to see a resumption of our more normal mobile pattern of weather anytime soon, it does look as though conditions could become much more unsettled towards the end of next week, meaning potentially much wetter conditions for parts of the UK.

The ECMWF (European Centre for Medium Range Forecasting) chart shown below for next saturday indicates low pressure in charge by that time.

Looking even further ahead, I thought the latest forecast temperature charts from NOAA (National Oceanic and Atmospheric Administration) were very interesting.

Note how virtually the whole of Europe through Autumn and next Winter is once more colder than average.

It's a long way off, but it suggests that weather patterns are likely to remain more blocked than normal across Europe. With average solar activity continuing to be weak, coupled with the likelihood of developing La Nina conditions (cooling of surface waters in the tropical eastern Pacific Ocean) later this year, the odds on a cold winter across Europe must once again be higher than normal.

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The idea that changes in solar activity can affect our weather and climate has very much fallen out of fashion in recent times. Most climate scientists' efforts have been directed towards the impact of greenhouse gases on global temperatures, and what a warmer planet could mean to weather and climate.

Most, but not all, meteorologists dismiss the idea that the sun could play an important role in determining our weather, and hence climate.

This may, at least in part, be down to the fact that forecasts these days are heavily reliant on powerful supercomputers that can't incorporate the influence of the sun, simply because the precise mechanism of how the sun impacts our weather is either not understood, or impossible to model.

But it wasn't that long ago that eminent climatologists such as Professor Lamb at the University of East Anglia conducted research which showed, amongst other things, a link between low solar activity and pressure patterns over Greenland.

In his day forensic analysis of weather data was the only way to forecast the weather, but sadly much of his work, and work like it, has been mostly forgotton, as the weather industry becomes more and more reliant on computer simulations of the atmosphere.

But it seems that it may becoming a fashionable area of research once more.

In my article 'Could the sun cast a shadow on global temperatures' I featured research by Australian scientist David Archibald, who concluded that the prolonged solar minimum that we have just witnessed would lead to, amongst other things, colder European winters in the next decade.

Interestingly his research was published in 2008 long before the coldest winter in the UK since 1978/79 struck.

So it was with interest in April when I read that Professor Lockwood at Reading University conducted a similar analysis, and came to the same conclusion as Mr Archibald - that colder European winters in the next few years were possible because of the behaviour of the sun. You can see an article based on his research by clicking here.

But I wanted to highlight a fascinating piece of research that has been published in the Journal of Atmospheric and Solar-Terrestrial Physics. It again shows quite clearly a link between solar activity and temperature and pressure variability across Europe. You can read the research paper by clicking here, but here are some intriguing highlights:

1) A strong correlation is found between wintertime temperatures and pressure disturbances in Europe - which applies up to the most recent past and which, according to the authors, had not been previously reported.

2) The relationship between solar forcing and European climate is not stationary over a year, but strongly depends on the season, so simple averaging over the whole year may obscure the underlying forcing. The solar signature is present all over the 20th century in wintertime European temperature.

3) Solar modulation of temperature disturbances 'are by no means small'.

4) The authors believe they have uncovered a regional (European) expression of a global phenomena.

5) The study shows that the evolution of temperature disturbances remains linked with solar activity up to present.

6) Physical processes and feedbacks possibly linking climate variations to solar variations are not fully understood.

The authors conclude that 'the role of the sun in global and regional climatic change should be re-assessed'.

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