This is the latest from Urumqi, China, 43N 87E, 3011 ft:

ZWWW 151200Z 35002MPS CAVOK 25/M35 Q1012 NOSIG

For those unfamiliar with METARs this says: Wind N force 2
No cloud
below 5000 ft
Temp 25,
dewpoint -35
MSL pressure
1012.

The "translation" says humidity 0% but in fact it is just about 1%. The
station-level pressure is 908 mb, so I shouldn't take the sea level pressure
too seriously. The upper air ascent (for 0000 Z) doesn't show this very dry
air anywhere near the surface, so its origin is a bit of a mystery, unless the
data are wrong.

Tudor Hughes, Warlingham, Surrey.

TudorHgh wrote:
This is the latest from Urumqi, China, 43N 87E, 3011 ft:

ZWWW 151200Z 35002MPS CAVOK 25/M35 Q1012 NOSIG

For those unfamiliar with METARs this says: Wind N force 2
No cloud
below 5000 ft
Temp 25,
dewpoint -35
MSL pressure
1012.

The "translation" says humidity 0% but in fact it is just about 1%. The
station-level pressure is 908 mb, so I shouldn't take the sea level pressure
too seriously. The upper air ascent (for 0000 Z) doesn't show this very dry
air anywhere near the surface, so its origin is a bit of a mystery, unless the
data are wrong.

Tudor Hughes, Warlingham, Surrey.

Tudor,

Thank you very much for the translation. I often see raw METARs in this
group and struggle to find the point of interest. Sometimes I find it
but often I give up. The translation also helps me to become more
familiar with the raw METARs. Well done.
--
Howard Neil

TudorHgh wrote in message ...
: This is the latest from Urumqi, China, 43N 87E, 3011 ft:
:The "translation" says humidity 0% but in fact it is just about 1%. The
:station-level pressure is 908 mb, so I shouldn't take the sea level
pressure
:too seriously. The upper air ascent (for 0000 Z) doesn't show this very
dry
:air anywhere near the surface, so its origin is a bit of a mystery, unless
the
:data are wrong.

A set of 4 hourly observations with DP below -25°C so perhaps we can assume
they are correct http://weather.noaa.gov/weather/current/ZWWW.html

As Urumqui - like the rest of China - is 8 hours ahead of UTC this is the
early evening.

Interesting that Tianjin - near the NE coast of China and SE of Beijing -
reported a similar phenomenon
http://weather.noaa.gov/weather/current/ZBTJ.html Dry bulb 29°C and
DP -33°C ! Abrupt fall in DP to an extremely low level at the hottest part
of the day - and subsequent rise to a "normal" level in the evening and
night.

Colin Youngs
Brussels

Thanks, Howard. I left a little bit out, actually. CAVOK means "cloud
AND visibility OK" which means vis greater than 10 km as well as no cloud below
5000 ft. In practice it often means no cloud at all - one just has to guess.
If the vis is below 10 km and the sky clear then the term SKC is used.
I don't think raw METARs (or SYNOPs) should be posted. I've done it
myself in the past but it's a bit offhand, even if there's a link to an
explanatory page.

Tudor Hughes.

"Howard Neil" wrote in message
news:6UAfc.33270$Y%

Tudor,

Thank you very much for the translation. I often see raw METARs in this
group and struggle to find the point of interest. Sometimes I find it
but often I give up. The translation also helps me to become more
familiar with the raw METARs. Well done.
--
Howard Neil


You may want to try this Howard
http://heras-gilsanz.com/manuel/METAR-Decoder.html

Interesting that Tianjin - near the NE coast of China and SE of Beijing -
reported a similar phenomenon
Dry bulb 29°C and
DP -33°C ! Abrupt fall in DP to an extremely low level at the hottest part
of the day - and subsequent rise to a "normal" level in the evening and
night.

I am a little suspicious of these figures, with their diurnal variation
being the same, roughly, as at Urumqi. Air that dry at his time of year can
only have arrived by adiabatic descent from some way up, despite:

A set of 4 hourly observations with DP below -25°C so perhaps we can assume
they are correct

Tudor Hughes.

TudorHgh wrote:

Thanks, Howard. I left a little bit out, actually. CAVOK means "cloud
AND visibility OK" which means vis greater than 10 km as well as no cloud below
5000 ft. In practice it often means no cloud at all - one just has to guess.
If the vis is below 10 km and the sky clear then the term SKC is used.

Thanks. That has been noted.

--
Howard Neil

"TudorHgh" wrote in message


Thanks, Howard. I left a little bit out, actually. CAVOK means "cloud
AND visibility OK" which means vis greater than 10 km as well as no cloud below
5000 ft. In practice it often means no cloud at all - one just has to guess.
If the vis is below 10 km and the sky clear then the term SKC is used.
Snip

Furthermore, continental METARs and UK TAFs use NSC (Nil Significant
Cloud) if the only cloud is 5000FT or above and not CB - assuming CAVOK
conditions don't apply.

Jon.


--
Posted via Mailgate.ORG Server - http://www.Mailgate.ORG

Joe, Bedford. wrote:


You may want to try this Howard
http://heras-gilsanz.com/manuel/METAR-Decoder.html

Thanks, that may be useful. However I tried entering the METAR provided
by Tudor and it only gave a partial translation. It missed out the
important bit about the humidity. The translation given was:

Location: ZWWW
Day of month: 15
Time: 12:00 UTC
Wind: True direction = 350 degrees, Speed: 2 m/s

I also notice that Tudor gave wind speed as force 2 whereas the above
translation is in m/s.

--
Howard Neil