Archives for November 2012

Cold to follow latest deluge

Paul Hudson | 16:11 UK time, Monday, 26 November 2012

A welcome change to drier but colder weather is likely as we head through this week following heavy rainfall since Saturday night which is once again testing flood defences across the county.

November is continuing a remarkable run of wet weather, becoming the 8th successive month where rainfall has been above average, a sequence which began in April.

Rainfall has not yet been of the same magnitude as that which caused the River Ouse to rise just short of record levels in September, when 100mm fell in 50 hours at Leeming, 76mm of that in just 24 hours.

So far at the same station 52mm had been recorded in the 40 hours to 1200 today - still a lot of rain though - equating to a month's worth in less than 2 days.

Normally, this wouldn't cause problems with river flooding, but because the land is so saturated in what is already one of the wettest years on record, rivers have risen faster and higher than would normally have been the case.

Another 10-20 mm of rain is expected generally in the next 18 hours across Yorkshire, with additional totals as high as 50mm across some higher Pennine and North York moor river catchments.

Through this week somewhat colder air is expected to spread southwards as pressure starts to rise.

This will result in weather systems being 'blocked' from moving eastwards across the country, at least in the short term.

The good news is that this means weather conditions will become much drier generally, although showers are still expected more especially in eastern areas exposed to the northerly breeze.

Frosts will develop inland from mid-week and some of the showers will become wintry, more especially over the hills, although they are not expected to cause a problem.

Looking further ahead into early December, there is a split between computer models.

Some want to see a return of the less cold and wetter westerlies (like for example arguably the most reliable ECMWF model), with others keeping colder, drier conditions especially across the North and East of the UK.

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What's behind the 'coldest winter for 100 years' headline?

Paul Hudson | 15:16 UK time, Monday, 19 November 2012

Those of us with a keen interest in the weather can't fail to have noticed yet another headline in the Express this weekend, claiming this winter would be the coldest in 100 years, which you can see here.

Wherever I went this weekend, I've been stopped in the street by people asking me when the awful weather is likely to hit, whether they should buy winter tyres for the car, or go ahead with a planned visit to relatives at Christmas.

The headline in the Express came courtesy of little known 'Exacta Weather', a tiny private weather company, which bases its forecasts on, amongst other things, variations in solar output.

But the headline this weekend is almost identical to the one from this time last year, in which the same 'Exacta Weather' forecasted severe wintry conditions throughout last winter, leading to yet another front page headline in the Express.



In the end, last winter was milder than average.

Exacta Weather is by no means the only company to issue such forecasts.

The headline in the Express is one of over twenty in the newspaper in recent times, all claiming severe or extreme conditions were about to befall us, each one of them the result of press releases from small, private weather companies, and most of which turned out to be wrong or exaggerated.

So what's going on?

When I worked at the Met Office some years ago, I remember the press office contacted a tabloid newspaper to ask why they continued to print such weather stories which invariably turned out to be wrong.

Their answer was very honest, straightforward and unapologetic.

Weather sells newspapers they said; admitting that each and every time they had a front page story on extreme weather, their circulation went up by around 10%.

Whether the forecast was right or wrong didn't seem a concern, after all, the newspaper was only reporting on what was being forecast by the weather company in question. How did they know whether it would turn out to be right or wrong?

And one would assume that any small private weather company, in a difficult completely un-regulated sector which is dominated by the state-funded Met Office, is happy to get some free, valuable publicity.

So it's a mutually beneficial process.

The losers, of course, are the readers, and more importantly the whole weather industry itself, which gets tarred with the same brush as those who issue extreme, sensationalist forecasts, which rarely bare any resemblance to reality.

So will it be the coldest winter in 100 Years?

It's extremely unlikely and if it were to happen it would be a huge turn up for the books.

Of course, if it were to happen, the many, many misleading headlines based on questionable forecasts that have appeared in recent years would quickly be forgotten.

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Antarctica sea ice & latest global temperatures

Paul Hudson | 16:05 UK time, Monday, 12 November 2012

ANTARCTICA

The record breaking Arctic sea ice minimum recorded this summer (based on satellite data) was well documented in the media and on this blog.

Conversely, at the other end of the world, little mention was made of the Antarctica ice extent which approached a record high in September, according to the US National Snow and Ice Data Centre (NSIDC).

According to new research conducted by the British Antarctic Survey, published in Nature Geoscience, changing wind patterns around Antarctica are thought to have caused the increase in ice, with wind flows pushing sea ice outwards helping to increase its extent.

Climate models have failed to reproduce this overall increase in sea ice.

The new research says that sea ice is not able to expand by the same mechanism in the Arctic because if winds push the ice away from the pole it quickly hits land, as the Arctic is an ocean surrounded by a continent - whereas because Antarctica is a continent surrounded by water, ice can expand.

But according to the British Antarctic survey, the Arctic is losing sea ice five times faster than the Antarctic is gaining it.


Latest Global temperatures

Global temperatures in October remained at elevated levels.

According to the UAH satellite measure the global temperature was 0.331C above the 30 year running average in October.

Adjusted to the standard 1961-1990 measure, global temperatures were 0.584C above average, making it the 2nd warmest October globally since the start of satellite data in 1979.

These warm global conditions are despite temperatures in equatorial Pacific areas remaining neutral.

In fact, a continuation of neutral temperature conditions (neither colder La Nina nor warmer El Nino) are now favoured during the Northern Hemisphere winter, and the El Nino watch has been cancelled.

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'High risk' of further flooding this winter

Paul Hudson | 17:04 UK time, Monday, 5 November 2012

Ground water levels remain unseasonably high across parts of Yorkshire following the very wet conditions this summer, according to the Environment Agency.

Although autumn is traditionally the wettest season of the year, the land is more saturated than normal because of excessive rainfall since the end of March, leading to an increased risk of further river flooding throughout the remainder of the year.

In fact with little if any evaporation during the winter months, rivers are likely to remain susceptible to further flooding until spring next year, when evaporation rates increase once more and the land is given a chance to dry out.

October continued the wet theme, turning out to be another disappointing month.

Rainfall averaged across England and Wales was 120 per cent of the 1981-2010 average. This means that only 22 Octobers were wetter in the last 100 years.

It was colder than average too, with a Central England Temperature of 9.7C, making it the coldest October since 2003. This is 1C below the 1981-2010 average, and in the last 100 years only 27 were colder.

The first half of November is likely to remain unsettled, with further rain expected at times.

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