Boscastle Weather rain hazard

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Boscastle Weather (rain) hazard

• August 18th 2004

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What was the Weather Like?It was summer but it
really poured down!
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But if you are asked about a weather hazard you
must say a rainstorm (a flood is not a weather
event)
We are reducing our case studies by using
Boscastle as a weather hazard and also as a flood
hazard
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On the run-up to the flood some 200 millimetres
(mm) of rain fell in 24 hours.
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Most of this fell in a 5 hour period on Monday,
August 16th with peak intensities of over 300 mm
per hour (5 mm per minute). However the storm was
very localised and four of the nearest 10 rain
gauges - all within a few miles of Boscastle -
showed less than 3 mm.
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Studies of extreme rainfall patterns have
concluded that freak floods are more likely to
occur in June, July and August than at any other
month of the year. They are Convectional
Thunderstorms. This is when atmospheric
conditions, such as a warm ground surface,
typically found during summer, lead to the uplift
of air masses which subsequently cool, producing
cloud and rainfall formations.
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Bands of showers aligned themselves with winds
that had converged along the coastal high ground
around Boscastle, creating Cumulonimbus clouds
12192m (40,000ft) high and kept them stationary
for many hours
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August 04, 2004 Look Out Kirsty! It looks like
Hurricane Alex is heading towards the UK. I know
by then it won't technically be a hurricane, but
you guys still might get some rain from it.
At midday, on the 16th August 2004, heavy,
thundery showers had developed across the South
West, these were the remnants of Hurricane Alex
which had crossed the Atlantic.
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How were people affected?

• Short Term (hours, days)
• Medium Term (weeks, months)
• Long Term (months, years)

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Immediate concern save lives 100 airlifted to
safety from rooftops. No accoimmodation.
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The clear up loss of tourist income hardship
and stress. Insurance claims but good for builders
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Back to normality It was a freak one in 200 year
rain event No special protection measures