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Trouble brewing
Problems began in the second week of October when a complex area
of low pressure developed over Scotland and Northern Ireland,
bringing wind and heavy rain. At this time, Kent and Sussex particularly
were affected by slow-moving torrential downpours which produced
100-150 mm of rain overnight on 11/12 October.
Over the next fortnight, low pressure became established to the
north-west of the UK, and this drove belt after belt of heavy
rain and showers across the country. In some parts significant
amounts of rain fell every day. By the final week of October many
rivers were either greatly swollen or had burst their banks.
It was then that the problems really began.
Three in a row
A deep depression became anchored near south-west Iceland and
developed a cold front that trailed way down into the North Atlantic.
One after another, three very active depressions formed from waves
on the cold front, each tracking across the UK on successive days
- 28, 29 and 30 October.
The first brought a period of heavy rain in many places, with
up to 8 mm an hour reported across parts of the Home Counties.
Sunshine and blue skies greeted the 29th, but the second depression
was already on its way. Rain set in around mid-afternoon, spreading
across much of the southern part of the country, accompanied by
strong winds.
The third depression, on the 30th was the most damaging of the
three. Rain had fallen all night, so, by 0900, 24-hour totals
of 25-50 mm were commonplace, with locally 75 mm and more. Local
flooding occurred and caused major disruption to commuters during
the morning rush hour. In a number of areas, the cumulative effect
of these heavy storms brought the situation close to breaking
point, and the heavy rain on 30 October resulted in much more
serious flooding problems in areas as far apart as Kent, Wales
and Yorkshire.
Surprise, surprise...more rain
The Met Office again forecast heavy rain in early November, and
it arrived as expected on the 5th. It was the last thing people
wanted, but more than 50 mm of rain fell in England and Wales,
and prolonged heavy rain also affected the northern half of the
UK. Flooding was once again a problem across large areas.
Wettest autumn
In late November the autumn of 2000 was declared the wettest
since records began in 1766. In all, 503 mm of rain fell during
this exceptionally wet and unsettled period. In October, 188 mm
of rain was recorded in England and Wales, followed by 182 mm
in November. In all, the total for 2000 was 251 mm above the average
for this season.
Improving forecasts of future floods
The severity and extent of flooding depends to a large degree
on the state of the underlying ground - if the soil moisture content
is already high, flooding occurs much more quickly because surface
water cannot soak away. During the floods the Met Office worked
closely with the Environment Agency, advising on the amount, intensity
and duration of rainfall to enable the agency to make accurate
updates to its Floodline warning service.
After the floods the Met Office joined forces with the Centre
for Ecology and Hydrology to form the Joint Centre for Hydrological
Research with the aim of improving flood forecasting in the future.
The centre's work includes the development of a detailed map and
model of soil wetness for the whole of the UK. The map is updated
every hour with data from weather radars, satellites, rain gauges
and other real-time observations. Information about soil wetness has
applications in, for example, farming, military operations and, of
course, flooding, and the model is used to help the Environment Agency
issue flood warnings to the emergency services and the public.
More
about the storms of October 2000
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