Geoscience Reference
In-Depth Information
APPENDIX 3
Synoptic weather maps
Table A3.1
Synoptic code (World Meteorological Organization, January 1982)
Symbol Key
Example
Comments
yy
Day of the month (GMT)
05
All groups are in blocks
GG
Time (GMT) to nearest hour
06
{ of 5 digits
i
w
Indicator for type of wind speed observation
4
Measured by
and units
anemometer (knots)
IIiii
International index number of station
i
R
Indicator: precipitation data included/omitted (code)
3
Data omitted
i
X
Indicator: station type + ww W1 W2 included/
1
Manned station with
omitted (code)
ww W1 W2 included
h
Height of lowest cloud (code)
3
vv
Visibility (code)
66
N
Total cloud amount (oktas)
7
dd
Wind direction (tens of degrees)
32
ff
Wind speed (knots, orm s-1)
20
Knots
I
Header
1
S
n
Sign of temperature (code)
0
Positive value
TTT
Temperature (0.1°C), plotted rounded to nearest 1°C
203
(1 = negative value)
2
Header
2
S
n
Sign of temperature (code)
0
T
d
T
d
T
d
Dewpoint temperature (as TTT)
138
4
Header
4
PPPP
Mean sea-level pressure (tenths of mb, omitting thousands)
0105
5
Header
5
a
Characteristic of pressure tendency (coded symbol)
3
ppp
3-hour pressure tendency (tenths of mb)
005
7
Header
7
ww
Present weather (coded symbol)
80
W
1
Past weather (coded symbol)
9
(W
1
must be greater
W
2
Past weather (coded symbol)
8
}
than W
2
)
8 Header 8
N
h
Amount of low cloud (oktas) 4
C
L
Low cloud type (coded symbol) 2
C
M
Medium cloud type (coded symbol) 5
C
H
High cloud type (coded symbol) 2
Note: Group 3 is for a report of surface pressure and group 6 for precipitation data.
