Evershot, WDorset: 185m (607ft) amsl
09:00z 08/01/11
7.1°C
Max 9.9°C, min 6.9°C
Dewpoint 6.4°C
RH 95%
Wind 1 kts WNW
995.4 hPa Rising
Ppn (standard gauge) 14.1mm last 24hrs
Ppn (standard gauge) 48.2mm this month
Ppn (standard gauge) 30-day rolling total 79.4mm
Ppn (AWS) 0.4mm last 24hrs
Ppn (AWS) 24.0mm this month

Overcast, gusty, mildish, damp in the air
I think the wind must have blown the rain over the top of the AWS

Hugh

--

Hugh Newbury

www.evershot-weather.org

On 08/01/2011 09:58, Hugh Newbury wrote:
Evershot, WDorset: 185m (607ft) amsl
09:00z 08/01/11
snip
Ppn (standard gauge) 14.1mm last 24hrs
Ppn (standard gauge) 48.2mm this month
Ppn (standard gauge) 30-day rolling total 79.4mm
Ppn (AWS) 0.4mm last 24hrs
Ppn (AWS) 24.0mm this month

Overcast, gusty, mildish, damp in the air
I think the wind must have blown the rain over the top of the AWS

.... I think it must have done! I recorded 10.6 mm in the 24hr to 09Z
(5inch) and 9.1 mm (electronic); Of the latter, 2.7 mm came last night.

I've only got a 'cheapo' electronic gauge (irox) - only tips in 0.7mm
increments which might sound daft but after a year of use I find I can
monitor the broad pattern of daily rainfall quite well with it. Have
just done a comparison with the adjacent 5 inch, and the electronic is
~10% low w.r.t. 5 inch, which is what I had assumed. I've found that if
I scale-up the electronic monthly total by a flat 10% (which is an easy
calculation to do of course), I get very close to the total as standard.

Martin.


--
Martin Rowley
Location: West Moors, East Dorset (UK): 17m (56ft) amsl
Lat: 50.82N Long: 01.88W
NGR: SU 082 023
W: booty.org.uk
E:

On 08/01/11 10:30, Martin Rowley wrote:
On 08/01/2011 09:58, Hugh Newbury wrote:
Evershot, WDorset: 185m (607ft) amsl
09:00z 08/01/11
snip
Ppn (standard gauge) 14.1mm last 24hrs
Ppn (standard gauge) 48.2mm this month
Ppn (standard gauge) 30-day rolling total 79.4mm
Ppn (AWS) 0.4mm last 24hrs
Ppn (AWS) 24.0mm this month

Overcast, gusty, mildish, damp in the air
I think the wind must have blown the rain over the top of the AWS

... I think it must have done! I recorded 10.6 mm in the 24hr to 09Z
(5inch) and 9.1 mm (electronic); Of the latter, 2.7 mm came last night.

I've only got a 'cheapo' electronic gauge (irox) - only tips in 0.7mm
increments which might sound daft but after a year of use I find I can
monitor the broad pattern of daily rainfall quite well with it. Have
just done a comparison with the adjacent 5 inch, and the electronic is
~10% low w.r.t. 5 inch, which is what I had assumed. I've found that if
I scale-up the electronic monthly total by a flat 10% (which is an easy
calculation to do of course), I get very close to the total as standard.

Martin, Last year the total in the AWS was 73% of the total in the 5in
gauge here. But the AWS is at head-height even though just beside the
5in. I remember John Dann saying that if I put the collector of the AWS
at the same height as the 5in, they would show much nearer the same. But
I promised Philip Eden that I would publish comparisons between the AWS
and the 5in he had very kindly lent me, so I let them both do their own
thing.

Hugh

Martin, Last year the total in the AWS was 73% of the total in the 5in
gauge here. But the AWS is at head-height even though just beside the
5in. I remember John Dann saying that if I put the collector of the AWS
at the same height as the 5in, they would show much nearer the same. But
I promised Philip Eden that I would publish comparisons between the AWS
and the 5in he had very kindly lent me, so I let them both do their own
thing.

Hugh

I think exposure is the key to a considerable extent. My AWS is at 1m
height but in a sheltered back garden so the effect of any wind is not
particularly great. My annual rainfall totals seem quite reasonable when I
compare them to data available from the Met Office website.

Although I am not down by the rivers here the site is in the vale of St
Albans and is surrounded by higher ground in all directions except to the
NE and I think we get less rain here than the sorrounding higher ground.

This year I have melted the snow and measured the raifall equivalent but I
am sure that some snowfall escaped when transferring it from the funnel.

Alan