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Is recent flooding and heavy rainfall unusual?

I've written at length about the excessive rainfall the UK has experienced, particularly last year but also since the late 1990's; six out of the years from 1998 to 2012 are in the top ten wettest on record, based on Met Office rainfall data which began in 1910.

There are various theories as to why our summers have been so wet, and why the jet stream has been further south than normal.

It's worth remembering as exceptional as the last few years have seemed, climate history shows us that flooding in the UK has always been normal.

This point is highlighted in research which was carried out by Durham University following the serious summer floods in 2007 and highlighted on the website this week.

The research is five years old, but it rings very true today, and the prediction made in 2008 of increased flooding and heavy rainfall in subsequent years has proved to be all too correct.

The author Professor Stuart Lane looked back at rainfall patterns starting in the mid 1700's.

He concluded that our climate has always fluctuated between very wet and very dry periods, some of which lasted for a few decades.

Crucially the period from the early 1960's to the late 1990's saw far fewer river flooding episodes compared with before the 1960's and after the 1990's.

Ominously, he points out that because more than three quarters of our flood records started during the 1960's, when there were far fewer river flooding episodes, we have underestimated the frequency of flooding.

And this has a knock on effect as to how much flood plain development local authorities will allow.

It's a vicious circle as more flood plain development is likely to make any future flooding even worse.

The article on the Durham University website can be found

UK weather outlook:

The heavy snow that brought disruption to parts of the UK on Friday has melted rapidly as a result of milder air and rainfall.

The next 48 hours will be dominated by a very common January weather pattern, with a powerful jet stream bringing rain or showers to all areas, accompanied by strong to gale force winds.

There's uncertainty about Friday's weather though, with an Atlantic depression expected to bring rain to parts of the UK.

Just how far north the rain will come is open to question, but with colder air pushing southwards as it clears away, some of it could turn to snow.

2012 Global temperatures:

Provisional Met Office figures show that 2012 was the 9th warmest on record, 0.45C above the 1961-1990 average. This is very close to their prediction for 2012 which was for a global temperature 0.48C above the 1961-1990 average.

According to the UAH satellite temperature measure, 2012 was also the 9th warmest on record.

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Amounts of snow across some parts of our region are the deepest since December 2010, with 21 cms being reported at Pateley Bridge in Nidderdale at midday, and a notable 18 cms in the middle of Sheffield at Weston park.

Waddington in Lincolnshire is reporting 14 cms of snow.

There are some big contrasts though, with only 2cms reported at Church Fenton in the Vale of York.

The snow, on Friday and last night, was forecast well in advance and first signalled at the beginning of last week.

Further snowfall is likely on the North York moors tonight, but for many it should become dry, with the main hazard being that of widespread ice.

Patchy rain, sleet and snow in coastal areas tomorrow will push inland to affect some areas, but further snowfall amounts will be small.

A change to milder weather will come at the weekend, with rain, preceded by some snow; the last week of January looks much milder with rain at times.

The thaw, when it comes could be rapid and with the ground already saturated from last year's excessive rainfall, flooding is likely to be a concern.

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Many parts of Yorkshire and Lincolnshire had their first snowfall of the winter yesterday, with coastal areas suffering the largest falls with around 10cms (4 ins) of fresh snow being reported by yesterday evening.

Temperatures could easily reach -10C (14F) in rural locations where there's snow cover during the next couple of nights.

But by the end of the week and into the weekend, things will become much more interesting, as weather fronts make the first of what could be two attempts to bring less cold air in from the Atlantic, with a risk of snow and disruption to travel.

As is always the case in these situations there's a lot of uncertainty about how fast the less cold air moves north-eastwards.

Experience suggests that computer models are often too quick to replace cold continental air.

Current indications are that the first Atlantic weather front will push across our area through Friday night and into Saturday as a weakening feature, bringing some increasingly light snow.

The next more active weather front will bring heavier snow on Sunday, which will eventually turn to rain as less cold air spreads eastwards.

But to highlight the uncertainty, some solutions are quicker with the snow and bring it across Yorkshire and Lincolnshire on Friday, with others slower.

There's bound to be changes to the timing of these systems as we get nearer the event, but there's clearly a risk of disruptive snow as we head into the weekend.

Next week looks very unsettled, and although the air will be somewhat less cold, temperatures are still likely to below average, with rain at times which could easily turn to snow in places, especially over the hills.

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