Identical maximum/minimum
 

Having just recovered from the New Year festivities(!) I've
realised there were some examples of identical maximum and minimum
temperatures reported in the January 2nd SYNOPS. Heathrow at 5.4/5.4
and Solent at 5.8/5.8 for example.

Obviously, with the way max and mins are reported, this can happen on
any cloudy/windy Winter day if a colder airstream moves in during the
morning but it always strikes me as odd when it does happen, quite
misleading really. The true 00Z/00Z max/mins at Solent near me were
about +7C and +1C respectively.

I'm sure this has been debated many times before (though I can't find
it at this unearthly morning hour) but could someone please remind me
of the logic underlying the reporting of daily extremes in this way?
It never ceases to irritate me whenever it crops up! Grrrr!

/grumpy mode OFF :)

--
Dave

Identical maximum/minimum
 

wrote in message
...
Having just recovered from the New Year festivities(!) I've
realised there were some examples of identical maximum and minimum
temperatures reported in the January 2nd SYNOPS. Heathrow at 5.4/5.4
and Solent at 5.8/5.8 for example.

Obviously, with the way max and mins are reported, this can happen on
any cloudy/windy Winter day if a colder airstream moves in during the
morning but it always strikes me as odd when it does happen, quite
misleading really. The true 00Z/00Z max/mins at Solent near me were
about +7C and +1C respectively.

Hi, Dave,

As is becoming more common as time goes by, I don't understand!

Are these obs for one hour, 09Z - 09Z, 00Z - 00Z?

Surely there will be at least a 0.1C range, even in an hour?

I've had the 09Z ob (and 00Z ob) as max or min for the 24hr period a few
times, but never both in 35 years' obs.

Not over bright mode still on.


--
Ken
http://mysite.freeserve.com/copley
kencookATcopleydurham.freeserve.co.uk





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Identical maximum/minimum
 

On Tue, 6 Jan 2004 08:11:19 -0000, "Ken Cook"
wrote:

wrote in message
.. .
Having just recovered from the New Year festivities(!) I've
realised there were some examples of identical maximum and minimum
temperatures reported in the January 2nd SYNOPS. Heathrow at 5.4/5.4
and Solent at 5.8/5.8 for example.

Are these obs for one hour, 09Z - 09Z, 00Z - 00Z?

Surely there will be at least a 0.1C range, even in an hour?

I've had the 09Z ob (and 00Z ob) as max or min for the 24hr period a few
times, but never both in 35 years' obs.

Oh dear, I didn't explain that at all well (up far too early!). The
SYNOP reports are, I believe, for 18Z - 06Z reported at 06Z (minimum),
and 06Z - 18Z reported at 18Z (maximum). So my question should really
have been, why is this the apparently standard practice, as (if I am
correct) it will produce misleading results from time to time.

Logically, shouldn't extreme daily temperature values always cover the
same (24 hour) period. Ideally 00Z to 00Z but I *do* understand why
the observation time varies and I have no problem with that!
In the case of Solent and Heathrow the "overnight" minimum must have
occurred at 06 GMT but the temperature continued to fall as colder air
arrived, so the "day maximum" also occurred at 06 GMT.

This seems an odd way to "officially" do things, or have I
misunderstood the whole thing? Perhaps climatalogical stations record
differently.

--
Dave

Identical maximum/minimum
 

We usually get a long thread every year on this subject. Philip or Martin
step in and all becomes clear for about 10 minutes. Then when it happens the
next year I'm still confused.
Dave

"Dave Ludlow" wrote in message
...
On Tue, 6 Jan 2004 08:11:19 -0000, "Ken Cook"
wrote:

wrote in message
.. .
Having just recovered from the New Year festivities(!) I've
realised there were some examples of identical maximum and minimum
temperatures reported in the January 2nd SYNOPS. Heathrow at 5.4/5.4
and Solent at 5.8/5.8 for example.

Are these obs for one hour, 09Z - 09Z, 00Z - 00Z?

Surely there will be at least a 0.1C range, even in an hour?

I've had the 09Z ob (and 00Z ob) as max or min for the 24hr period a few
times, but never both in 35 years' obs.

Oh dear, I didn't explain that at all well (up far too early!). The
SYNOP reports are, I believe, for 18Z - 06Z reported at 06Z (minimum),
and 06Z - 18Z reported at 18Z (maximum). So my question should really
have been, why is this the apparently standard practice, as (if I am
correct) it will produce misleading results from time to time.

Logically, shouldn't extreme daily temperature values always cover the
same (24 hour) period. Ideally 00Z to 00Z but I *do* understand why
the observation time varies and I have no problem with that!
In the case of Solent and Heathrow the "overnight" minimum must have
occurred at 06 GMT but the temperature continued to fall as colder air
arrived, so the "day maximum" also occurred at 06 GMT.

This seems an odd way to "officially" do things, or have I
misunderstood the whole thing? Perhaps climatalogical stations record
differently.

--
Dave

Identical maximum/minimum
 

"Dave.C" wrote in message
...
We usually get a long thread every year on this subject. Philip or Martin
step in and all becomes clear for about 10 minutes. Then when it happens
the
next year I'm still confused.

Try:

http://groups.google.com/groups?hl=e...%26scoring%3Dd

Philip Eden :-)

Identical maximum/minimum
 

"Dave Ludlow" wrote in message Oh
dear, I didn't explain that at all well (up far too early!). The
SYNOP reports are, I believe, for 18Z - 06Z reported at 06Z (minimum),
and 06Z - 18Z reported at 18Z (maximum).

Hi, Dave and Dave,

Yes, I see now - it's the day max and night min for the two separate
periods scenario.

ATB,

--
Ken
http://mysite.freeserve.com/copley
kencookATcopleydurham.freeserve.co.uk



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Identical maximum/minimum
 

This has been a area of discussion for many years......
In mid-winter the min usually occurs around 0900z. I believe the minimum
for climatological purposes is that for 2100 to 0900 and the max 0900to
2100. Possibly something to do with the large numbers of 'amateurs' in the
system who would resent staying up till say 2400 to take the max reading.
I'm not sure why a minimum temp is given on synops at 0600Z.
I agree periods 00 - 12 for min and 12 - 24 for max would make more sense.
Not being a 'climatological' buff I expect others will explain things
better and possibly more correctly.
Cheers
John
--
York,
North Yorkshire.
(Norman Virus Protected)

"Dave Ludlow" wrote in message
...
On Tue, 6 Jan 2004 08:11:19 -0000, "Ken Cook"
wrote:

wrote in message
.. .
Having just recovered from the New Year festivities(!) I've
realised there were some examples of identical maximum and minimum
temperatures reported in the January 2nd SYNOPS. Heathrow at 5.4/5.4
and Solent at 5.8/5.8 for example.

Are these obs for one hour, 09Z - 09Z, 00Z - 00Z?

Surely there will be at least a 0.1C range, even in an hour?

I've had the 09Z ob (and 00Z ob) as max or min for the 24hr period a few
times, but never both in 35 years' obs.

Oh dear, I didn't explain that at all well (up far too early!). The
SYNOP reports are, I believe, for 18Z - 06Z reported at 06Z (minimum),
and 06Z - 18Z reported at 18Z (maximum). So my question should really
have been, why is this the apparently standard practice, as (if I am
correct) it will produce misleading results from time to time.

Logically, shouldn't extreme daily temperature values always cover the
same (24 hour) period. Ideally 00Z to 00Z but I *do* understand why
the observation time varies and I have no problem with that!
In the case of Solent and Heathrow the "overnight" minimum must have
occurred at 06 GMT but the temperature continued to fall as colder air
arrived, so the "day maximum" also occurred at 06 GMT.

This seems an odd way to "officially" do things, or have I
misunderstood the whole thing? Perhaps climatalogical stations record
differently.

--
Dave

Identical maximum/minimum
 

"Ken Cook" wrote in message
...
"Dave Ludlow" wrote in message Oh
dear, I didn't explain that at all well (up far too early!). The
SYNOP reports are, I believe, for 18Z - 06Z reported at 06Z
(minimum),
and 06Z - 18Z reported at 18Z (maximum).

Hi, Dave and Dave,

Yes, I see now - it's the day max and night min for the two separate
periods scenario.

.... some countries (the Germans and French come to mind) report both 1
and 2 gps at 06 and 18Z which is quite a good way to get around some of
these problems. AFAIK, there is no good reason why the UK can't follow
suit - it's allowed for in the coding conventions.

Martin.
--
FAQ & Glossary for uk.sci.weather at:-
http://homepage.ntlworld.com/booty.weather/uswfaqfr.htm

Identical maximum/minimum
 

"John Whitby" wrote in message
...
| This has been a area of discussion for many years......
| In mid-winter the min usually occurs around 0900z. I believe the minimum
| for climatological purposes is that for 2100 to 0900 and the max 0900to
| 2100. Possibly something to do with the large numbers of 'amateurs' in the
| system who would resent staying up till say 2400 to take the max reading.

How about students finding it hard getting up at 09z ?!

Joe

Identical maximum/minimum
 

On Tue, 6 Jan 2004 14:53:22 -0000, "Philip Eden"
philipATweatherHYPHENukDOTcom wrote:


"Dave.C" wrote in message
...
We usually get a long thread every year on this subject. Philip or Martin
step in and all becomes clear for about 10 minutes. Then when it happens
the
next year I'm still confused.

Try:

http://groups.google.com/... huge link snippified

Philip Eden :-)

Thanks Philip, I remember that thread now. I did look, but failed to
find it. I've read it now.

What concerns me is not so much what time of day the readings are
taken, it doesn't seem to be a great problem if readings are
attributed to the "wrong" day as long as none are missed altogether.
But with the "night min/day max" method (18-06-18), whatever times are
chosen, is it not true that some daily extremes can be completely lost
to the long term record? Even if 21-09-21 or other times are used
instead?

Long winded example: It's 30th January in Fareham and until this
morning, it's been mildish all month. Yesterday's min was +6C and the
max +8C. But the temperature has been dropping this morning since 3 am
as much colder air is advected South and is down to +3C by 06GMT. It
continues to get colder and by 10 am, is down to -2C and frosty. But
the sky is now clearing and the wind is dropping out. Ooh, I think to
myself excitedly, we've just had our first air frost of the month and
lowest minimum of the winter! At last!

By 11am, the sun is shining brightly and the afternoon maximum
eventually creeps up to +6 degrees in my old wooden Stevenson screen.
But the cold snap is short lived here, of course. Tonight (30th/31st)
has a minimum of +4C, occurring at 19GMT, as cloud increases ahead of
a warm front from the West and the temperature starts to rise.
Followed by days and days of mild Westerlies.

Is it not true that using the 18-06-18 method (as in SYNOPS), the
minimum today (30th) would be recorded as +3 (at 06 GMT) and
tomorrow's minimum (31st) as +4 (at 19 GMT)? My month's minimum, and
the one and only air frost, has been lost to the official records
forever (not just pushed into the wrong day or month) hasn't it?

If true, that's what concerns me most about the 18-06-18 method. It
seems to strengthen greatly the case for the seemingly more logical
method of recording one max and one min for each successive 24 hour
period. Far better to have the maximum or minimum temperature
attributed to the wrong day or month than to have them lost
completely, I'd say.

Unless, of course, I've got it completely wrong in me advancing old
age... :)

--
Dave