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Old August 13th 18, 09:12 AM posted to uk.sci.weather
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Default Heavy rain in south Wales

On Monday, 13 August 2018 08:56:25 UTC+1, Graham Easterling wrote:
On Sunday, August 12, 2018 at 10:50:56 PM UTC+1, wrote:
On Sunday, August 12, 2018 at 6:46:18 PM UTC+1, Graham Easterling wrote:
On Sunday, August 12, 2018 at 5:43:57 PM UTC+1, Len wrote:
On Sunday, August 12, 2018 at 12:49:37 PM UTC+1, Freddie wrote:
On Sunday, 12 August 2018 11:57:21 UTC+1, Graham Easterling wrote:



36.4 mm here on SW Devon coast.
Now that is wet for us.
Not a 24 hr record though.
That was 48.6 mm 0n 25th Aug 1986.


Ah, in that case you beat me. My wettest August day 52.0mm 3rd 1997.

Graham

But 52.0 48.6, so you win Graham :-)

--
Freddie
Ystrad
Rhondda
148m AMSL
http://www.hosiene.co.uk/weather/
https://twitter.com/YstradRhonddaWx for hourly reports (no wind measurement currently)

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Old August 13th 18, 09:39 AM posted to uk.sci.weather
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Default Heavy rain in south Wales

On Monday, August 13, 2018 at 9:12:39 AM UTC+1, Freddie wrote:
On Monday, 13 August 2018 08:56:25 UTC+1, Graham Easterling wrote:
On Sunday, August 12, 2018 at 10:50:56 PM UTC+1, wrote:
On Sunday, August 12, 2018 at 6:46:18 PM UTC+1, Graham Easterling wrote:
On Sunday, August 12, 2018 at 5:43:57 PM UTC+1, Len wrote:
On Sunday, August 12, 2018 at 12:49:37 PM UTC+1, Freddie wrote:
On Sunday, 12 August 2018 11:57:21 UTC+1, Graham Easterling wrote:


36.4 mm here on SW Devon coast.
Now that is wet for us.
Not a 24 hr record though.
That was 48.6 mm 0n 25th Aug 1986.


Ah, in that case you beat me. My wettest August day 52.0mm 3rd 1997.

Graham

But 52.0 48.6, so you win Graham :-)

--
Freddie


It's obviously too early in the morning for me!

Graham
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Old August 13th 18, 10:15 AM posted to uk.sci.weather
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Default Heavy rain in south Wales

On Monday, August 13, 2018 at 9:39:10 AM UTC+1, Graham Easterling wrote:
On Monday, August 13, 2018 at 9:12:39 AM UTC+1, Freddie wrote:
On Monday, 13 August 2018 08:56:25 UTC+1, Graham Easterling wrote:
On Sunday, August 12, 2018 at 10:50:56 PM UTC+1, wrote:
On Sunday, August 12, 2018 at 6:46:18 PM UTC+1, Graham Easterling wrote:
On Sunday, August 12, 2018 at 5:43:57 PM UTC+1, Len wrote:
On Sunday, August 12, 2018 at 12:49:37 PM UTC+1, Freddie wrote:
On Sunday, 12 August 2018 11:57:21 UTC+1, Graham Easterling wrote:


36.4 mm here on SW Devon coast.
Now that is wet for us.
Not a 24 hr record though.
That was 48.6 mm 0n 25th Aug 1986.

Ah, in that case you beat me. My wettest August day 52.0mm 3rd 1997.

Graham

But 52.0 48.6, so you win Graham :-)

--
Freddie


It's obviously too early in the morning for me!

Graham


I had n't realised this was a competition.
All good fun.
Now on 24th Aug 1986 we had 14.5 mm.
So for the 2-day period 24th and 25th we had 63.1 mm.
My wettest 2-day August period.
Can you beat that?

Len
Wembury, SW Devon
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Old August 13th 18, 10:44 AM posted to uk.sci.weather
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Default Heavy rain in south Wales

Len wrote:

On Sunday, August 12, 2018 at 12:49:37 PM UTC+1, Freddie wrote:
On Sunday, 12 August 2018 11:57:21 UTC+1, Graham Easterling wrote:
On Sunday, August 12, 2018 at 10:37:05 AM UTC+1, Freddie wrote:
I recorded 68.2 mm at my site in the 24 hours ending at 0900z.
I wasn't the highest, though. A place called Llety Brongu
(which is in the valley of the Llynfi river, near Maesteg -
about 8 miles to the southwest of Ystrad) had recorded 75.0 mm
up to 0700z. I don't know what their 09-09 total was, though,
and have no other figures to hand.

Puts my 25.2mm into perspective!

Graham
Penzance A vastly better day - currently

Just a typical wet day here, Graham :-) I actually recorded more
on 29th July - 69.8 mm. No real impacts here as it is a fairly
normal total - the river rose about a metre for a short while.

Not that I'm used to it - having lived in the Shropshire/Powys rain
shadow for the past 25 years.

--
Freddie
Ystrad
Rhondda
148m AMSL
http://www.hosiene.co.uk/weather/
https://twitter.com/YstradRhonddaWx for hourly reports (no wind
measurement currently)


36.4 mm here on SW Devon coast.
Now that is wet for us.
Not a 24 hr record though.
That was 48.6 mm 0n 25th Aug 1986.

Wembury, SW Devon
83 m asl


When you say 'not a 24-hour record' is that what you really mean, Len?
Or do you mean 'not an 09z-09z record'? There is a difference :-)

--
Norman Lynagh
Tideswell, Derbyshire
303m a.s.l.
https://peakdistrictweather.org
Twitter: @TideswellWeathr
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Old August 13th 18, 10:47 AM posted to uk.sci.weather
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Default Heavy rain in south Wales

Nick Gardner wrote:

On 12/08/2018 17:43, Len wrote:
36.4 mm here on SW Devon coast.
Now that is wet for us.
Not a 24 hr record though.
That was 48.6 mm 0n 25th Aug 1986.


26.2 mm here Len for the last 24 hours. That's the greatest 24 hour
total this year beating 19.1 mm on the 1st July.

Same point as I raised with Len, Nick. Do you really mean 'greatest
24-hour total' or do you mean 'greatest 09z to 09z total'?


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


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Old August 13th 18, 01:59 PM posted to uk.sci.weather
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Default Heavy rain in south Wales

On Monday, August 13, 2018 at 10:15:22 AM UTC+1, wrote:
On Monday, August 13, 2018 at 9:39:10 AM UTC+1, Graham Easterling wrote:
On Monday, August 13, 2018 at 9:12:39 AM UTC+1, Freddie wrote:
On Monday, 13 August 2018 08:56:25 UTC+1, Graham Easterling wrote:
On Sunday, August 12, 2018 at 10:50:56 PM UTC+1, wrote:
On Sunday, August 12, 2018 at 6:46:18 PM UTC+1, Graham Easterling wrote:
On Sunday, August 12, 2018 at 5:43:57 PM UTC+1, Len wrote:
On Sunday, August 12, 2018 at 12:49:37 PM UTC+1, Freddie wrote:
On Sunday, 12 August 2018 11:57:21 UTC+1, Graham Easterling wrote:


36.4 mm here on SW Devon coast.
Now that is wet for us.
Not a 24 hr record though.
That was 48.6 mm 0n 25th Aug 1986.

Ah, in that case you beat me. My wettest August day 52.0mm 3rd 1997.

Graham
But 52.0 48.6, so you win Graham :-)

--
Freddie


It's obviously too early in the morning for me!

Graham


I had n't realised this was a competition.
All good fun.
Now on 24th Aug 1986 we had 14.5 mm.
So for the 2-day period 24th and 25th we had 63.1 mm.
My wettest 2-day August period.
Can you beat that?

Len
Wembury, SW Devon


Well yes (not that I'm being competitive!)

Biggest 2 day Aug total
3rd/4th Aug 1997 95.1mm
Biggest 3 day Aug total
2nd/3rd/4th Aug 1997 120.0mm!

Looking back SE wind & pressure around 1010, so the sort of conditions for feeding up thundery rain. Those 3 days made it my wettest August by a very big margin, with 236.9mm. In 2nd place 2015 with 162.9mm

All 09:00-09:00 totals Norman!

Graham
Penzance
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Old August 13th 18, 03:13 PM posted to uk.sci.weather
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Default Heavy rain in south Wales

On Monday, August 13, 2018 at 10:44:58 AM UTC+1, Norman Lynagh wrote:
Len wrote:

On Sunday, August 12, 2018 at 12:49:37 PM UTC+1, Freddie wrote:
On Sunday, 12 August 2018 11:57:21 UTC+1, Graham Easterling wrote:
On Sunday, August 12, 2018 at 10:37:05 AM UTC+1, Freddie wrote:
I recorded 68.2 mm at my site in the 24 hours ending at 0900z.
I wasn't the highest, though. A place called Llety Brongu
(which is in the valley of the Llynfi river, near Maesteg -
about 8 miles to the southwest of Ystrad) had recorded 75.0 mm
up to 0700z. I don't know what their 09-09 total was, though,
and have no other figures to hand.

Puts my 25.2mm into perspective!

Graham
Penzance A vastly better day - currently
Just a typical wet day here, Graham :-) I actually recorded more
on 29th July - 69.8 mm. No real impacts here as it is a fairly
normal total - the river rose about a metre for a short while.

Not that I'm used to it - having lived in the Shropshire/Powys rain
shadow for the past 25 years.

--
Freddie
Ystrad
Rhondda
148m AMSL
http://www.hosiene.co.uk/weather/
https://twitter.com/YstradRhonddaWx for hourly reports (no wind
measurement currently)


36.4 mm here on SW Devon coast.
Now that is wet for us.
Not a 24 hr record though.
That was 48.6 mm 0n 25th Aug 1986.

Wembury, SW Devon
83 m asl


When you say 'not a 24-hour record' is that what you really mean, Len?
Or do you mean 'not an 09z-09z record'? There is a difference :-)

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


Yes Norman, hereby lies a problem with any amateur observers in the old days when they were working. They were usually out by 0900 so had to take measurements at 1800. I was one of these. Nowadays there are AWSs which solve the problem in some respects. My 5-inch standard gauge 24 hr totals are useful in a long clmate record, Same instrument same place.

I think there is still a problem, as I understand it a daily total is 0900 to 0900 officially. But many owners of AWSs will report midnight to midnight as a daily total. Seems logical.

My 24 hr totals are 1800 to 1800.
What's 6 hours difference between friends?
Only joking.

Len
Wembury


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Old August 13th 18, 04:03 PM posted to uk.sci.weather
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Default Heavy rain in south Wales

wrote:

On Monday, August 13, 2018 at 10:44:58 AM UTC+1, Norman Lynagh wrote:
Len wrote:

On Sunday, August 12, 2018 at 12:49:37 PM UTC+1, Freddie wrote:
On Sunday, 12 August 2018 11:57:21 UTC+1, Graham Easterling
wrote:
On Sunday, August 12, 2018 at 10:37:05 AM UTC+1, Freddie
wrote:
I recorded 68.2 mm at my site in the 24 hours ending at
0900z. I wasn't the highest, though. A place called Llety
Brongu (which is in the valley of the Llynfi river, near
Maesteg - about 8 miles to the southwest of Ystrad) had
recorded 75.0 mm up to 0700z. I don't know what their
09-09 total was, though, and have no other figures to hand.

Puts my 25.2mm into perspective!

Graham
Penzance A vastly better day - currently
Just a typical wet day here, Graham :-) I actually recorded
more on 29th July - 69.8 mm. No real impacts here as it is a
fairly normal total - the river rose about a metre for a short
while.

Not that I'm used to it - having lived in the Shropshire/Powys
rain shadow for the past 25 years.

--
Freddie
Ystrad
Rhondda
148m AMSL
http://www.hosiene.co.uk/weather/
https://twitter.com/YstradRhonddaWx for hourly reports (no wind
measurement currently)

36.4 mm here on SW Devon coast.
Now that is wet for us.
Not a 24 hr record though.
That was 48.6 mm 0n 25th Aug 1986.

Wembury, SW Devon
83 m asl


When you say 'not a 24-hour record' is that what you really mean,
Len? Or do you mean 'not an 09z-09z record'? There is a difference
:-)

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


Yes Norman, hereby lies a problem with any amateur observers in the
old days when they were working. They were usually out by 0900 so had
to take measurements at 1800. I was one of these. Nowadays there are
AWSs which solve the problem in some respects. My 5-inch standard
gauge 24 hr totals are useful in a long clmate record, Same
instrument same place.

I think there is still a problem, as I understand it a daily total is
0900 to 0900 officially. But many owners of AWSs will report midnight
to midnight as a daily total. Seems logical.

My 24 hr totals are 1800 to 1800.
What's 6 hours difference between friends?
Only joking.

Len
Wembury


That is, indeed, an issue Len but not quite the point that I was
making. My point applies equally to amateur and professional observing.

Let's consider a station where daily totals are reported 0900 to 0900.
Let's also assume that on a particular day there is a spell of heavy
rain between 0700 and 1100 with a total of 50 mm falling, 25 mm before
0900 and 25 mm after 0900. If no other rain falls during the two
relevant rainfall days scenario will give two daily 0900-0900 totals of
25mm each, completely hiding the fact that 50mm fell in only 4 hours.
This means that there would actually be a 24-hour total of 50mm even
though each of the 0900 to 0900 'rainfall days' would have only 25mm
each. This sort of anomaly occurs quite frequently, when heavy rain
spans the cut-off time for daily rainfall reporting. If measurements
are taken using a manual rain gauge read once or twice daily there's no
way of identifying the true maximum 24-hour total in such a case. Data
from recording rain gauges or modern AWS can assist.

The important point, though, when discussing daily/24-hour totals is to
make it clear exactly what is being referred to. It might be 0900 to
0900 or 1800 to 1800 or whatever, Or, it might be a true maximum
24-hour total derived from a recording rain gauge or an AWS. More often
than not, in any month the maximum 24-hour total will be higher than
the highest total for any fixed 24-hour period such as 0900 to 0900 or
1800 to 1800. This is something we just have to live with.

--
Norman Lynagh
Tideswell, Derbyshire
303m a.s.l.
https://peakdistrictweather.org
Twitter: @TideswellWeathr
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Old August 13th 18, 05:18 PM posted to uk.sci.weather
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Default Heavy rain in south Wales


I recorded 68.2 mm at my site in the 24 hours ending at
0900z. I wasn't the highest, though. A place called Llety
Brongu (which is in the valley of the Llynfi river, near
Maesteg - about 8 miles to the southwest of Ystrad) had
recorded 75.0 mm up to 0700z. I don't know what their
09-09 total was, though, and have no other figures to hand.

Puts my 25.2mm into perspective!

Graham
Penzance A vastly better day - currently
Just a typical wet day here, Graham :-) I actually recorded
more on 29th July - 69.8 mm. No real impacts here as it is a
fairly normal total - the river rose about a metre for a short
while.

Not that I'm used to it - having lived in the Shropshire/Powys
rain shadow for the past 25 years.

--
Freddie
Ystrad
Rhondda
148m AMSL
http://www.hosiene.co.uk/weather/
https://twitter.com/YstradRhonddaWx for hourly reports (no wind
measurement currently)

36.4 mm here on SW Devon coast.
Now that is wet for us.
Not a 24 hr record though.
That was 48.6 mm 0n 25th Aug 1986.

Wembury, SW Devon
83 m asl

When you say 'not a 24-hour record' is that what you really mean,
Len? Or do you mean 'not an 09z-09z record'? There is a difference
:-)

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


Yes Norman, hereby lies a problem with any amateur observers in the
old days when they were working. They were usually out by 0900 so had
to take measurements at 1800. I was one of these. Nowadays there are
AWSs which solve the problem in some respects. My 5-inch standard
gauge 24 hr totals are useful in a long clmate record, Same
instrument same place.

I think there is still a problem, as I understand it a daily total is
0900 to 0900 officially. But many owners of AWSs will report midnight
to midnight as a daily total. Seems logical.

My 24 hr totals are 1800 to 1800.
What's 6 hours difference between friends?
Only joking.

Len
Wembury


That is, indeed, an issue Len but not quite the point that I was
making. My point applies equally to amateur and professional observing.

Let's consider a station where daily totals are reported 0900 to 0900.
Let's also assume that on a particular day there is a spell of heavy
rain between 0700 and 1100 with a total of 50 mm falling, 25 mm before
0900 and 25 mm after 0900. If no other rain falls during the two
relevant rainfall days scenario will give two daily 0900-0900 totals of
25mm each, completely hiding the fact that 50mm fell in only 4 hours.
This means that there would actually be a 24-hour total of 50mm even
though each of the 0900 to 0900 'rainfall days' would have only 25mm
each. This sort of anomaly occurs quite frequently, when heavy rain
spans the cut-off time for daily rainfall reporting. If measurements
are taken using a manual rain gauge read once or twice daily there's no
way of identifying the true maximum 24-hour total in such a case. Data
from recording rain gauges or modern AWS can assist.

The important point, though, when discussing daily/24-hour totals is to
make it clear exactly what is being referred to. It might be 0900 to
0900 or 1800 to 1800 or whatever, Or, it might be a true maximum
24-hour total derived from a recording rain gauge or an AWS. More often
than not, in any month the maximum 24-hour total will be higher than
the highest total for any fixed 24-hour period such as 0900 to 0900 or
1800 to 1800. This is something we just have to live with.

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


Yes, 24 hr totals have limited interest.
Event totals are more interesting and of immediate relevance to water authorities and emergency services.

Len
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Old August 19th 18, 07:52 PM posted to uk.sci.weather
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Posts: 774
Default Heavy rain in south Wales

On 13/08/2018 10:47, Norman Lynagh wrote:
Same point as I raised with Len, Nick. Do you really mean 'greatest
24-hour total' or do you mean 'greatest 09z to 09z total'?


Norman, it is a 24-hour total, i.e., greatest rainfall in any 24-hour
period.

--
Nick Gardner
Otter Valley, Devon
20 m amsl
http://www.ottervalleyweather.me.uk


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