Around 200mm (thanks Bernard) rain fell near Coverack in this afternoons major thunderstorm. (See my "West Cornwall Dramatic Variations in weather post" - Penzance saw 24C & prolonged sunshine, no rain) Almost all the rain fell prior to this morning Weather Warning start, which was 17:00, by which time the sun was back out in Coverack. The most severe period was 14:00-16:00, the 200mm falling in approx 3 hours. Not just rain but hail, lightning, trees down - the full works. Also major problems for people out in small boats due to the rapidly changing sea conditions.

There is a very serious situation unfolding with people washed along in the floods, and all roads into Coverack impassable. 1st news appeared on twitter https://twitter.com/hashtag/coverack . Spotlight's just ended with them only just realising what had happened, though DB still said some places had 20-30mm in a short space of time, with Plymouth worst affected. Doesn't he follow the radar imagery?

I'm sure Coverack won't be the only place severely affected.

Let's hope it's only property seriously damaged.

GrahamPenzance

Graham Easterling wrote:

Around 200mm (thanks Bernard) rain fell near Coverack in this afternoons
major thunderstorm. (See my "West Cornwall Dramatic Variations in weather
post" - Penzance saw 24C & prolonged sunshine, no rain) Almost all the rain
fell prior to this morning Weather Warning start, which was 17:00, by which
time the sun was back out in Coverack. The most severe period was
14:00-16:00, the 200mm falling in approx 3 hours. Not just rain but hail,
lightning, trees down - the full works. Also major problems for people out in
small boats due to the rapidly changing sea conditions.

There is a very serious situation unfolding with people washed along in the
floods, and all roads into Coverack impassable. 1st news appeared on twitter
https://twitter.com/hashtag/coverack . Spotlight's just ended with them only
just realising what had happened, though DB still said some places had
20-30mm in a short space of time, with Plymouth worst affected. Doesn't he
follow the radar imagery?

I'm sure Coverack won't be the only place severely affected.

Let's hope it's only property seriously damaged.

GrahamPenzance

As I have said on here before, the Severe Weather Warning Service, as it is
currently structured, is not fit for purpose. No doubt money, or lack of it, is
a very relevant factor but a warning service that doesn't work is probably
worse than no warning service at all.

--
Norman Lynagh
Tideswell, Derbyshire
303m a.s.l.
http://peakdistrictweather.org
Twitter: @TideswellWeathr

On Tuesday, July 18, 2017 at 7:57:57 PM UTC+1, Norman Lynagh wrote:
Graham Easterling wrote:

Around 200mm (thanks Bernard) rain fell near Coverack in this afternoons
major thunderstorm. (See my "West Cornwall Dramatic Variations in weather
post" - Penzance saw 24C & prolonged sunshine, no rain) Almost all the rain
fell prior to this morning Weather Warning start, which was 17:00, by which
time the sun was back out in Coverack. The most severe period was
14:00-16:00, the 200mm falling in approx 3 hours. Not just rain but hail,
lightning, trees down - the full works. Also major problems for people out in
small boats due to the rapidly changing sea conditions.

There is a very serious situation unfolding with people washed along in the
floods, and all roads into Coverack impassable. 1st news appeared on twitter
https://twitter.com/hashtag/coverack . Spotlight's just ended with them only
just realising what had happened, though DB still said some places had
20-30mm in a short space of time, with Plymouth worst affected. Doesn't he
follow the radar imagery?

I'm sure Coverack won't be the only place severely affected.

Let's hope it's only property seriously damaged.

GrahamPenzance

As I have said on here before, the Severe Weather Warning Service, as it is
currently structured, is not fit for purpose. No doubt money, or lack of it, is
a very relevant factor but a warning service that doesn't work is probably
worse than no warning service at all.

--
Norman Lynagh
Tideswell, Derbyshire
303m a.s.l.
http://peakdistrictweather.org
Twitter: @TideswellWeathr

The last major thunderstorms & flooding (due to rain) in Cornwall was Sept 2016. http://www.turnstone-cottage.co.uk/2...nderstorms.pdf

There was no warning issued at any point. It was 6 months before some of the businesses flooded were up & running again

Graham
Penzance

Rooftop rescue clip from Coverack

https://www.youtube.com/watch?v=u0abRnhabqc

Compilation of images
https://www.youtube.com/watch?v=uOgqdkeN2XM

There's a lot of holiday cottages at the far end of the road past Coverack Harbour. Even if they are OK, they are currently pretty inaccessible. For the businesses it could not come at a worse time. Also huge amounts of sand have been stripped away & replaced by all sorts of rubbish.

Graham
Penzance (Still no rain whatsoever)

On 2017-07-18 18:11:55 +0000, Graham Easterling said:

Around 200mm (thanks Bernard) rain fell near Coverack in this
afternoons major thunderstorm. GrahamPenzance


In this article, the Environment Agency syuggests it was half that

http://www.bbc.co.uk/news/uk-england-cornwall-40652594

More than enough in any event.


--
Asha
minnies.opcop.org.uk
nature.opcop.org.uk
pictures.opcop.org.uk

On Wednesday, July 19, 2017 at 1:02:25 PM UTC+1, Asha Santon wrote:
On 2017-07-18 18:11:55 +0000, Graham Easterling said:

Around 200mm (thanks Bernard) rain fell near Coverack in this
afternoons major thunderstorm. GrahamPenzance


In this article, the Environment Agency syuggests it was half that

http://www.bbc.co.uk/news/uk-england-cornwall-40652594

More than enough in any event.


--
Asha
minnies.opcop.org.uk
nature.opcop.org.uk
pictures.opcop.org.uk

Yes, I think 100mm seems a realistic estimate (for that's what it is) of the rainfall in that general area, and for a fair area just offshore. There was, by local account & some evidence from the high res radar, a small area of exceptionally intense rain/hail, I think just to the north of Coverack, and it is there that totals may have approached 200mm. I hope to track down a possible recording over 160mm+. Sadly, as with most extreme events, we'll probably never actually know, official interest in actually recording the weather is at a depressing all time low.

The EA also said in their report after Boscastle that it was a 1 in 200 years event, despite the river having reached similar levels 3 times in living memory, and on one of those occasions a higher rainfall being recorded in an official gauge than in the 2004 event.

Graham

SNIP
On Tuesday, July 18, 2017 at 7:11:57 PM UTC+1, Graham Easterling wrote:
Around 200mm (thanks Bernard) rain fell near Coverack in this afternoons major thunderstorm. Almost all the rain fell prior to this morning Weather Warning start, which was 17:00, by which time the sun was back out in Coverack. The most severe period was 14:00-16:00,


Graham
Penzance

The official figure for the Coverack storm, seems to be just over 100mm, but I've now seen 2 separate reports indicating 160mm & 170mm. A small patch of torrential rain & large hail barely moved for some time.

The 170mm is essentially based on a bucket - but in the absence of anything else. https://www.coverack.org.uk/pages/news.html

Culdrose received 1mm during the period.

Graham
Penzance

On Thursday, July 20, 2017 at 2:54:39 PM UTC+1, Graham Easterling wrote:
SNIP
On Tuesday, July 18, 2017 at 7:11:57 PM UTC+1, Graham Easterling wrote:
Around 200mm (thanks Bernard) rain fell near Coverack in this afternoons major thunderstorm. Almost all the rain fell prior to this morning Weather Warning start, which was 17:00, by which time the sun was back out in Coverack. The most severe period was 14:00-16:00,


Graham
Penzance

The official figure for the Coverack storm, seems to be just over 100mm, but I've now seen 2 separate reports indicating 160mm & 170mm. A small patch of torrential rain & large hail barely moved for some time.

The 170mm is essentially based on a bucket - but in the absence of anything else. https://www.coverack.org.uk/pages/news.html

Culdrose received 1mm during the period.

Graham
Penzance

I should have included this:-

"Rainfall amount Mathematical challenge.
Tuesday 18th July 2017 in the afternoon
A three gallon builders’ bucket was used in the morning to carry wood chippings.
It was left empty in a space over two metres away from the nearest building..
On the evening of the same day the bucket contained water to a depth of 232mm.
The diameter of the top of the bucket was 310mm, with a lip to pour contents for
about one eighth of its circumference (120mm)
The volume of water contained in the bucket, measured the next day, was 13.014
litres. There was no perceptible change in level overnight.
This was measured by weighing the water in the bucket on bathroom scales 13..6Kg,
and subtracting the weight of the containing vessel, 586g.
I believe this gives a result of about 173mm of rainfall.
If the amount of rain added by the shape if the lip is removed, then I believe that
reduces the amount of rainfall to about 170mm."

The 160mm figure nearby was derived in a similar way.

Graham
Penzance

The rainfall in a bucket reminds me that the highest measured total of 9 inches for the Lynmouth flood of Aug 1952 came from a bucket that happened to have been left out in the middle of a field.
The biggest source of error in your example is probably the accuracy of the bathroom scales.

Dick Lovett

On Thursday, July 20, 2017 at 2:56:57 PM UTC+1, Graham Easterling wrote:
On Thursday, July 20, 2017 at 2:54:39 PM UTC+1, Graham Easterling wrote:
SNIP
On Tuesday, July 18, 2017 at 7:11:57 PM UTC+1, Graham Easterling wrote:
Around 200mm (thanks Bernard) rain fell near Coverack in this afternoons major thunderstorm. Almost all the rain fell prior to this morning Weather Warning start, which was 17:00, by which time the sun was back out in Coverack. The most severe period was 14:00-16:00,


Graham
Penzance

The official figure for the Coverack storm, seems to be just over 100mm, but I've now seen 2 separate reports indicating 160mm & 170mm. A small patch of torrential rain & large hail barely moved for some time.

The 170mm is essentially based on a bucket - but in the absence of anything else. https://www.coverack.org.uk/pages/news.html

Culdrose received 1mm during the period.

Graham
Penzance

I should have included this:-

"Rainfall amount Mathematical challenge.
Tuesday 18th July 2017 in the afternoon
A three gallon builders’ bucket was used in the morning to carry wood chippings.
It was left empty in a space over two metres away from the nearest building.
On the evening of the same day the bucket contained water to a depth of 232mm.
The diameter of the top of the bucket was 310mm, with a lip to pour contents for
about one eighth of its circumference (120mm)
The volume of water contained in the bucket, measured the next day, was 13.014
litres. There was no perceptible change in level overnight.
This was measured by weighing the water in the bucket on bathroom scales 13.6Kg,
and subtracting the weight of the containing vessel, 586g.
I believe this gives a result of about 173mm of rainfall.
If the amount of rain added by the shape if the lip is removed, then I believe that
reduces the amount of rainfall to about 170mm."

The 160mm figure nearby was derived in a similar way.

Graham
Penzance
Graham,
Can you say where this came from as it appears to be the original source for a discussion I have seen elsewhere?
Thanks,
David