Boscastle – Weather (rain) hazard August 18 th 2004.

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Boscastle – Weather (rain) hazard August 18 th 2004

Transcript of Boscastle – Weather (rain) hazard August 18 th 2004.

Page 1: Boscastle – Weather (rain) hazard August 18 th 2004.

Boscastle – Weather (rain) hazard

August 18th 2004

Page 2: Boscastle – Weather (rain) hazard August 18 th 2004.

What was the Weather Like?

It was summer but it really poured down!

Page 3: Boscastle – Weather (rain) hazard August 18 th 2004.

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 …

Page 4: Boscastle – Weather (rain) hazard August 18 th 2004.

On the run-up to the flood some 200 millimetres (mm) of rain fell in 24 hours.

Page 5: Boscastle – Weather (rain) hazard August 18 th 2004.

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.

Page 6: Boscastle – Weather (rain) hazard August 18 th 2004.

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 groundsurface, typically found during summer, lead to the uplift of air masses which subsequently cool, producing cloud and rainfall formations.

Page 7: Boscastle – Weather (rain) hazard August 18 th 2004.

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

Page 8: Boscastle – Weather (rain) hazard August 18 th 2004.

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.

August 04, 2004Look 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.

Page 9: Boscastle – Weather (rain) hazard August 18 th 2004.

How were people affected?

• Short Term (hours, days)

• Medium Term (weeks, months)

• Long Term (months, years)

Page 10: Boscastle – Weather (rain) hazard August 18 th 2004.

Immediate concern save lives – 100 airlifted to safety from rooftops.

No accoimmodation.

Page 11: Boscastle – Weather (rain) hazard August 18 th 2004.

The clear up – loss of tourist income – hardship and stress.

Insurance claims but good for builders

Page 12: Boscastle – Weather (rain) hazard August 18 th 2004.

Back to normality

It was a freak one in 200 year rain event

No special protection measures