Yesterday saw a daily range here of 18.0 degC, from min -1.8°C to max
16.2°C. Then overnight it fell back to -3.7°C, a 'max to min' range of
19.9 degC. Both are significantly higher than anything previously on
record for February, in almost 50 years daily records:

- The previous highest diurnal range (min to max) in Feb was 16.1 degC
(-3.3°C to +12.8°C) at Shinfield (6 km distant from here) on 19 Feb
1959

- The previous greatest fall from max to min in Feb was 16.2 degC
(12.7°C to -3.5°C) recorded at this site last year, on 3 Feb 2007.

--
Stephen Burt
Stratfield Mortimer, Berkshire

Min-max range here at Wokingham 16.7 C yesterday (screen), previous highest
Feb range in past 32 years was 16.4 C on 14th in 1998.
Good example of 'screen' effects yesterday, screen max 15.4 C, aspirated AWS
14.8 C (1 min means), Last night's screen min -3.3 C AWS -3.0 C .

--
Bernard Burton
Wokingham, Berkshire, UK.

Satellite images at:
www.woksat.info/wwp.html
or
www.btinternet.com/~wokingham.weather/wwp.html
wrote in message
...
Yesterday saw a daily range here of 18.0 degC, from min -1.8°C to max
16.2°C. Then overnight it fell back to -3.7°C, a 'max to min' range of
19.9 degC. Both are significantly higher than anything previously on
record for February, in almost 50 years daily records:

- The previous highest diurnal range (min to max) in Feb was 16.1 degC
(-3.3°C to +12.8°C) at Shinfield (6 km distant from here) on 19 Feb
1959

- The previous greatest fall from max to min in Feb was 16.2 degC
(12.7°C to -3.5°C) recorded at this site last year, on 3 Feb 2007.

--
Stephen Burt
Stratfield Mortimer, Berkshire

On Feb 10, 10:55*am, "Bernard Burton" b.j.burton-
wrote:
Min-max range here at Wokingham 16.7 C yesterday (screen), previous highest
Feb range in past 32 years was 16.4 C on 14th in 1998.
Good example of 'screen' effects yesterday, screen max 15.4 C, aspirated AWS
14.8 C (1 min means), Last night's screen min -3.3 C AWS -3.0 C .

--
Bernard Burton
Wokingham, Berkshire, UK.

Satellite images at:www.woksat.info/wwp.html
wrote in message

...
Yesterday saw a daily range here of 18.0 degC, from min -1.8°C to max
16.2°C. Then overnight it fell back to -3.7°C, a 'max to min' range of
19.9 degC. Both are significantly higher than anything previously on
record for February, in almost 50 years daily records:

- The previous highest diurnal range (min to max) in Feb was 16.1 degC
(-3.3°C to +12.8°C) at Shinfield (6 km distant from here) on 19 Feb
1959

- The previous greatest fall from max to min in Feb was 16.2 degC
(12.7°C to -3.5°C) recorded at this site last year, on 3 Feb 2007.

--
Stephen Burt
Stratfield Mortimer, Berkshire

Similar here in Surrey. Temperature has risen from - 0.9°C
to 16.0°C today, a record February diurnal range for this place,
starting 1983. It's not exactly late in the month, either, making
both the range and the max itself all the more remarkable. That's
easterlies in February for you. Some of the gloss was taken off the
warmth when I whirled the psychrometer in the shade and the dry bulb
read a mere 13.5, wet bulb 7.2, so dew point about -1°. But the
record book will say 16 max.

Tudor Hughes, Warlingham, NE Surrey, 556 ft.

Tudor Hughes wrote in
:

Similar here in Surrey. Temperature has risen from - 0.9°C
to 16.0°C today, a record February diurnal range for this place,

I see Norwich WC has reached 17c today. Glorious. I certainly pick unlucky
days to have to work...

Richard

On Sun, 10 Feb 2008 05:54:07 -0800 (PST), Tudor Hughes
wrote:

On Feb 10, 10:55*am, "Bernard Burton" b.j.burton-
wrote:
Min-max range here at Wokingham 16.7 C yesterday (screen), previous highest
Feb range in past 32 years was 16.4 C on 14th in 1998.
Good example of 'screen' effects yesterday, screen max 15.4 C, aspirated AWS
14.8 C (1 min means), Last night's screen min -3.3 C AWS -3.0 C .

Similar here in Surrey. Temperature has risen from - 0.9°C
to 16.0°C today, a record February diurnal range for this place,
starting 1983. It's not exactly late in the month, either, making
both the range and the max itself all the more remarkable. That's
easterlies in February for you. Some of the gloss was taken off the
warmth when I whirled the psychrometer in the shade and the dry bulb
read a mere 13.5, wet bulb 7.2, so dew point about -1°. But the
record book will say 16 max.

Thanks guys for reporting the aspirated temperatures as well as the
Stevenson Screen figures. Stevenson effect is a problem I have
regularly when I try to compare my own max-min temperatures with the
nearest official station Solent - which is an extreme axample because
of the screen's exposure. But if I move my screen out into the sunny
part of the garden, I will lose the ability to compare with past
records.

Screens shaded by a North wall may (along with aspirated and plastic
screens) give a more accurate reading of true air temperature but it
isn't much fun when everyone with a sunny screen gets excited about
near-record conditions and I never can.

--
Dave
Fareham

Dave Ludlow wrote:

Screens shaded by a North wall may (along with aspirated and plastic
screens) give a more accurate reading of true air temperature but it
isn't much fun when everyone with a sunny screen gets excited about
near-record conditions and I never can.


I'd rather have a true reading than one that is artificially high.

My Davis is fine in the garden from October half term to February half
term after which I move it to the north facing wall of the house, which
I find give very accurate maximum temperatures through the summer
months. I can compare this with Southend Airport. Of course I have a
problem with the night time minimums, so I have a max/min thermometer in
the garden where the Davis presides during the winter months.

Furthermore I am currently running in parallel a new Data Logging device
to get an idea of how comparible it is with the Davis. I've had to put
it into a protective box as it's not realy designed to be out in the
rain. I'm hoping I can use this to make the adjustments in the summer
months for the night time minimums. I'll report on my findings in a
couple of weeks when I have some comparisons to post.

http://www.southendweather.net/tr72u.jpg
http://www.southendweather.net/tr72u_2.jpg

http://www.loggershop.co.uk/tandd/us...r/prod_66.html
--
Keith (Southend)
http://www.southendweather.net
e-mail: kreh at southendweather dot net

On 10 Feb, 16:57, "Keith (Southend)"
wrote:

I'd rather have a true reading than one that is artificially high.


Well, two comments to that perhaps intentionally stirring line ;-)

1. The Stevenson screen isn't perfect, we know that. But it is the
standard, at least for now, and is our only means of comparing today's
records with historical records. For now, it's the benchmark for the
UK and Ireland and a good many other countries around the world.

2. The Davis passive radiation screen is - at least my one is - cooler
than my Stevenson screen on still, sunny days (= probably better).
Yesterday, my Davis max was 15.1°C which compared with 16.2°C in
adjacent Stevenson screen, although this is about as big a difference
as ever occurs, even in midsummer, and may be due to relatively low
solar angle. Max in adjacent small plastic (Gill-type) screen was
15.5°C. (Today, in the same order, 14.5°C, 15.7°, 15.4° - 0.6 lower,
0.5 lower, 0.1 lower).

As far as I have been able to do, all three sensors have been
calibrated to a standard logging sensor, itself calibrated less than 8
weeks ago, so I'm reasonably sure the differences are genuine rather
than calibration errors. All are exposed on an open plot meeting
standard site exposure criteria (COL grade A site).

The debate about screen types and aspiration will go on, I'm sure,
although I'm sure aspirated methods will become standard within the
next decade or two - but hopefully not until there are long overlaps
with conventional records, to avoid complete disruption to the long-
term temperature record the like of which we are now seeing with
historical
sunshine records.

--
Stephen Burt
Stratfield Mortimer, Berkshire

wrote:
On 10 Feb, 16:57, "Keith (Southend)"
wrote:

I'd rather have a true reading than one that is artificially high.


Well, two comments to that perhaps intentionally stirring line ;-)

1. The Stevenson screen isn't perfect, we know that. But it is the
standard, at least for now, and is our only means of comparing today's
records with historical records. For now, it's the benchmark for the
UK and Ireland and a good many other countries around the world.

2. The Davis passive radiation screen is - at least my one is - cooler
than my Stevenson screen on still, sunny days (= probably better).
Yesterday, my Davis max was 15.1°C which compared with 16.2°C in
adjacent Stevenson screen, although this is about as big a difference
as ever occurs, even in midsummer, and may be due to relatively low
solar angle. Max in adjacent small plastic (Gill-type) screen was
15.5°C. (Today, in the same order, 14.5°C, 15.7°, 15.4° - 0.6 lower,
0.5 lower, 0.1 lower).

As far as I have been able to do, all three sensors have been
calibrated to a standard logging sensor, itself calibrated less than 8
weeks ago, so I'm reasonably sure the differences are genuine rather
than calibration errors. All are exposed on an open plot meeting
standard site exposure criteria (COL grade A site).

The debate about screen types and aspiration will go on, I'm sure,
although I'm sure aspirated methods will become standard within the
next decade or two - but hopefully not until there are long overlaps
with conventional records, to avoid complete disruption to the long-
term temperature record the like of which we are now seeing with
historical
sunshine records.

--
Stephen Burt
Stratfield Mortimer, Berkshire



Stephen,

I was'nt trying to stir something up, what I was referring to was my own
garden location giving a higher reading on sunny days in summer. I could
use these readings and say I broke a record, yet I know it would be
wrong. Nothing to with screens or the like, the main thing I'm trying to
do is keep my own data to a standard so I can say with some confidence
whether I have broken a daily/monthly record, regardless of whether it
may actually be + or - a degree, although I like to think I'm within
0.3°C. ;-)

--
Keith (Southend)
http://www.southendweather.net
e-mail: kreh at southendweather dot net

On 10 Feb, 10:36, wrote:
Yesterday saw a daily range here of 18.0 degC, from min -1.8°C to max
16.2°C. Then overnight it fell back to -3.7°C, a 'max to min' range of
19.9 degC. Both are significantly higher than anything previously on
record for February, in almost 50 years daily records:

- The previous highest diurnal range (min to max) in Feb was 16.1 degC
(-3.3°C to +12.8°C) at Shinfield (6 km distant from here) on 19 Feb
1959

- The previous greatest fall from max to min in Feb was 16.2 degC
(12.7°C to -3.5°C) recorded at this site last year, on 3 Feb 2007.

Well, yesterday's near 50 year extreme daily range lasted only a day!

Today's (Stevenson screen) max was 15.7°C, down 0.5 degC on
yesterday's, but an astonishing range of 19.4 degC from the air
minimum -3.7°C. This is higher than any previous daily range for any
of the months November to February inclusive, in almost 50 years of
local daily records (my own for the last 21 years), although every
month March to October has exceeded 20 degC daily range at least once
(March highest 22.3 degC).

--
Stephen Burt
Stratfield Mortimer, Berkshire

Good example of 'screen' effects yesterday, screen max 15.4 C, aspirated
AWS
14.8 C (1 min means), Last night's screen min -3.3 C AWS -3.0 C .

Interesting. My max today in the Stevenson Screen was 15.5C and yet my Davis
AWS in its own circular screen which seems to be very good at keeping cool
in the sun recorded a max of 14.3C.

I always use the lower figure as I know that my Davis AWS temperature is
just about spot on. I also don't trust my sheathed thermometer ever since it
developed a break in the mercury (though I seemed to have managed to get it
to join back together).
________________
Nick G
Otter Valley, Devon
83 m amsl
http://www.ottervalley.co.uk