Wettest Summer Since Records Began - Can It Get Worse?

[Robbie Garrett]

It only seems like 5 minutes since we were suffering from months of prolonged dry weather with drought warnings, strange indeed.

This is certainly the wettest few months i can remember in London & i've lived here 15 years.

The next week looks very wet and cool so those totals will be ramping up even more. I can see July being one of the wettest ever.

Definitely balanced itself out. I am wondering if they may be a fixed pattern under low solar output. Really dry periods then really wet periods to balance itself out. Can you imagine if this was Winter right now. Greenland high, negative NAO and lots of low pressure.

[Coast]

Would someone please tell us why it won’t stop raining?

As the Met Office forecasts yet more downpours, what’s behind the bad weather, asks Michael Hanlon.

An old saying maintains that there is no such thing as bad weather, merely the wrong clothes. But the longer this damp, miserable, gloomy season continues, the harder it becomes to make excuses for the inglorious summer of 2012. The year might have started with winter drought and talk of hosepipe bans, but at least that held out the promise of a suitably sunny season in which to celebrate the Jubilee and Olympics. Yet after a scorching March, things went downhill. April was damp and cold, and May followed suit (albeit with a warm and dry final week). June was a washout (both it and April were the wettest on record across the UK) and July has not been much better. In some areas, it has rained nearly every day for the past month. Is this just natural variation in the climate, or something more sinister?

The “cause†of the wet weather is the jet stream, a high-altitude river of air flowing from west to east that governs the passage of weather fronts, depressions, high pressure zones and prevailing winds. The existence of such streams was not confirmed until the 1940s, when pilots of America’s new high-altitude bomber, the B29, found themselves being blown across the Pacific by 150mph tailwinds after bombing sorties over Japan.

The Atlantic jet stream is a kind of wall, separating the cool, wet and windy weather of the northern ocean from the stable, settled and warmer air to the south. In a good summer, the jet stream lies to the north of Britain, shielding us from the inclement weather closer to the Pole. But this year, it has shifted south, meaning that the cool, damp air has been able to set up home over the British Isles.

Of course, a wet summer is not unprecedented. The inestimable Weather of Britain by the late Robin Stirling charts every downpour, heatwave and drought in the UK since proper records began more than a century ago. So far our summer has been bad, but spare a thought for those who took a charabanc to the seaside 100 years ago. The summer of 1912 was “one of the wettest in the meteorological annalsâ€. Cornwall and Norfolk received more than three times the average August rainfall. And the night of August 25 saw more than 8in of rain fall on Norwich – over a quarter of the annual average. Parts of Norfolk were under water until spring. “It was fortunate,†says Stirling “that there were no steep slopes to accentuate the rush of water.†So far, despite significant flooding, we have seen nothing like that. Nor have we – yet – seen a summer to rival that of 1960, when five major depressions marched across the nation over July, bringing rain every day from Penzance to Fife.

Often, so-called “bad summers†are merely silly-season stories, generated by a wet weekend in August. A good example is the “washout†of 2009, which generated much derision after the Met Office predicted a “barbecue summerâ€: in fact, the summer of that year was rather average. We also believe our weather is worse than it is: few people realise that London is drier than Rome and Istanbul. Also, we tend not to appreciate that the weather isn’t the same for all of us. Generally, a wet summer will be felt disproportionally in what are usually the warmest and driest parts of the country. That has been the case this year as it was in 1912, when the Highlands had a glorious summer. Indeed, according to Met Office forecaster Dave Britton, “north and west Scotland were the only parts of the country experiencing below-average rainfall this Juneâ€.

Still, on the whole, 2012 has been terrible – generally wet and gloomy, especially across the south and east of England, where most of us live. Worse, the forecast is for at least a fortnight of downpours and drizzle. One reason why we may be feeling particularly sour is that, over the past 25 years, Britain has experienced a run of good summers. The years 1989 and 1990 saw long, hot dry spells, and the mid- and late 1990s saw more seasons of dry heat that did much to cement the notion of climate change in the public consciousness.

What is especially irritating is that scientists can offer no clear explanation for why, this year of all years, the jet stream has decided to head south. Global wind patterns are part of an unpredictable, often chaotic system, and predicting the position of a jet stream to a scale of a few hundred miles – which is enough to transform the weather in a country the size of Britain – can be impossible. “We simply do not know†is the Met Office’s response.

There will, inevitably, be suggestions that the current soggy weather might have something to do with climate change. It is hard to say for sure, but the answer is that it probably doesn’t. Predicting the impact of riding temperatures in Britain is difficult because we are sandwiched between the competing air masses of Eurasia and the Atlantic. This means, says Britton, that “a slight change in wind direction can make a tremendous differenceâ€. That said, according to this week’s New Scientist, the consensus is that even slight temperature rises have the potential to drive some pretty wild weather, and there is no reason to suppose that our archipelago will be immune. One startling statistic is that the air now contains 4 per cent more moisture than it did in the 1970s – and there has certainly been plenty of wild weather around, from the Russian floods this week to the terrible heatwaves affecting the United States.

Some climatologists have suggested that in a world that is warmer overall, we could see significant shifts in jet streams and prevailing winds, with regular incursions of solid polar air into northern Europe (including the British Isles). This trend could be triggered, paradoxically, by Arctic warming, as it is the contrast between that icy air and the warm air over the tropics that fuels the jet stream in the first place. Still, most models suggest that if anything, Britain will see drier, hotter summers and milder, wetter winters in future – although these average trends will be masked by short-term anomalies. There may be less summer rainfall, but what rain there is will come in shorter, heavier bursts – a more “tropical†rain pattern. Britain could, in other words, face the paradox of enduring drought and flood at the same time.

Is there anything good to say about the summer of 2012? The water companies are happy. The holidays have not yet started, and August could yet surprise us. Some people – more than would care to admit – hate hot weather, especially those forced to commute across our cities. And it does make our lawns and fields look that bit nicer. As Dave Britton says: “This is a green and pleasant land that we live in. And it is green and pleasant for a reason.â€

http://www.telegraph...op-raining.html

[johnholmes]

A decent article but what no one has pointed yet is that its NOT the jet stream that is the cause, that is an effect from the cause. The cause is?? Someone tell me please?

Why is the jet stream in this position, what has caused it to be where it is for so long?

answers on a postcard please!

[cyclonic happiness]

A decent article but what no one has pointed yet is that its NOT the jet stream that is the cause, that is an effect from the cause. The cause is?? Someone tell me please?

Why is the jet stream in this position, what has caused it to be where it is for so long?

answers on a postcard please!

I believe it's to do with the great extent of Arctic sea ice melt each year now, it seemed that since the lowest extent of recorded sea ice (wasn't it 2007?), we have had an erratic jet both summer and winter.

I'm not an expert but it does seem logical that the circulations of the ocean and air currants of the Northern Hemisphere, would be greatly affected by this massive change.

And the more time passes, the more sure I am of this being the case.

We should see by the end of the autumn if it's true.

[Coast]

A decent article but what no one has pointed yet is that its NOT the jet stream that is the cause, that is an effect from the cause. The cause is?? Someone tell me please?

Why is the jet stream in this position, what has caused it to be where it is for so long?

answers on a postcard please!

On Radio 4 this morning a climatologist from Reading was hinting it could be to do with global warming - I'm not even going to go there in this thread!

http://news.bbc.co.u...ain/default.stm

http://www.bbc.co.uk...urfm/listenlive

If you want to pursue it:

http://www.agu.org/pubs/crossref/pip/2012GL051000.shtml

[johnholmes]

I totally agree C-stay well away unless is solid armour with ear protectors as well

[knocker]

I totally agree C-stay well away unless is solid armour with ear protectors as well

Where is your spirit of adventure John. Be bold.....................where angels fear to tread.

[knocker]

On Radio 4 this morning a climatologist from Reading was hinting it could be to do with global warming - I'm not even going to go there in this thread!

That's quite interesting. I've read a couple of papers, or the summary of, that contributes the steady northward movement of the jet to warming at the tropics, around 30deg. either side of the equater. I'm wondering whether the perceived accelerating warming in the Arctic has reversed that trend. Of course it could just be a yearly anomaly and nothing at all to do with global warming but you have to wonder.

[Coast]

That's quite interesting.

Listen to Dr Edward Hanna's interview here on I-Player at 52.00 onwards:

http://www.bbc.co.uk...day_10_07_2012/

[Gray-Wolf]

If the Jet's positioning is being influenced by the masses of extra energy now being absorbed across the pole (check the Sst anoms where we have had early open water this spring/early summer!) then we're stuffed!

The Rockies set up the wave, and we can't alter that, and the amplitude is being messed with by the reduce temp/pressure profile from pole to equator. Add to that the 4% extra moisture that the air is now able to carry compared to 30yrs ago and you end up with 'Hebden Bridges' aplenty!

That said the seasonal shift ,north and south, of the Jet will mean us having another long, dry, Indian summer as the jet drops south for winter and we get a different 'stuck weather Pattern'. Global Weirding eh? Ya gotta love it! (not).

[BornFromTheVoid]

The full paper that much of the sea ice-jet stream link has come from is here

http://www.deas.harv...sVavrus2012.pdf

Combined with the fact that this year, April, May and June have had the 4th, 2nd and 1st lowest snow cover on record for the northern hemisphere respectively, a reduced thermal and thickness gradient between the tropics and Arctic may well be contributing to the current jet stream patterns.

http://climate.rutge...gs.php?ui_set=1