"Alan Gardiner" wrote in message
...


Will Hand wrote:
Just found out they got 58.1mm in Tavistock!

Will.

"Will Hand" wrote in message
...
11/10/06

Well the storms last night in Devon gave me a daily 1800-1800 total
of 56.4 mm. This is the highest 24 hour total I have ever recorded
since moving here. Last highest was 51.7 mm on 23/10/04. A very
large fall but not exceptional for this area.

There were 4 separate storm cells. The biggest was around 2340 local
which had a rainfall rate of 128.3 mm/h and a 20 minute total of 8.1
mm. Bar fell by 0.5 mp in 10 minutes 2340-2350 (wake low of storm).
Lots of lightning but thunder was intermittent. Rainfall, however,
was torrential but also came in short bursts. No problems up here
whatsoever (we never do with rain). Now like it has never happened.
Flash flooding elsewhere in Devon though.

Now, the manual total was 56.4 mm but my AWS VP2 read just 42.7 mm,
why the big discrepancy? All I can think of is that the rates were
so large that the tipping mechanism could not cope. A sobering
thought for users of AWS I think. Comments appreciated on this?

I'm chuffed. (a) we had a storm, (b) I got a pretty big rainfall
total.

Will.
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I assume that the ISS is around 1m off the ground and the manual gauge is at
ground level. Is there a possibility that the wind was stronger at 1m due to
the boundary layer effect and the rain was blown across the top of the ISS
during the heavy bursts of rain?


Alan we do get that effect fairly often with slanting rain (or snow) but on this
occasion the rain was coming down like stair rods, vertically.

I don't have a manual gauge to compare my own readings against but from the
monthly MO contoured maps I definitely think that my Davis station gives low
readings. It is possible to adjust the collector but without an accurate
gauge to work out the adjustment that is not really sensible. Perhaps I
need to think about getting a manual gauge.

I have lost very little data over the 5 years I have had the station so in
other respects the Davis has been excellent value and reliable. I did lose
some wind data when I had to get the anemometer repaired (reed switch
failed) but due to the position those readings are not accurate.


Yes they are reliable. Just not as good as a manual gauge. At some stage I'll
investigate the issue but no time yet as I have things like work and other
interests to fit in.

Cheers,

Will.
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