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Frequently Asked Questions
What does Synoptic Code look like?
SECTION 0
ii iRixhVV SECTION 1
Nddff 1snTTT 2snTdTdTd 4PPPP 5appp 6RRRtR 7wwW1W2 8NhCLCMCH SECTION 3
333 1snTxTxTx (@1800 UTC) 2snTnTnTn (@0600
UTC) 3EsnTgTg (@0600 UTC) 4E'sss (@0600 UTC) 8NsChshs 9SpSpspsp
SECTION 5
555 1V'f'/V'f''f'' 2snTwTwTw iiirrr.
Interpretation
SECTION 0
iii
Station Number
iRixhVV
iR Inclusion or omission of precipitation data (Table 1)
ix Inclusion or omission of weather group (Table 2)
h Height of base of lowest cloud (Table 3)
VV Horizontal visibility (Table 4)
SECTION 1
Nddff
N Total Cloud amount (Table 5)
dd Wind direction in tens of degrees (Table 6)
ff Wind speed in knots (Table 7)
1snTTT
1 Indicator
sn Sign of temperature (Table 8)
TTT Dry-bulb temperature in tenths of a degree Celsius
2snTdTdTd
2 Indicator
sn Sign of temperature (Table 8)
TdTdTd Dew-point temp. in tenths of a degree Celsius
4PPPP
4 Indicator
PPPP Last four figs. of air pressure (reduced to me sea level) in millibars
and tenths
5appp
5 Indicator
a Characteristic of pressure change (Table 9)
ppp Pressure change over last three hours in millibars and tenths
6RRRtR
6 Indicator
RRR Amount of rainfall (Table 10)
tR Duration of period of RRR in units of six hours. Main hours
only At 0001 and 1200 UTC tR=1 At 0600 and 1800 tR=2
7wwW1W2
7 Indicator ww Present weather, manned station (Table 11)
W1W2 Past weather, manned station (Table 22)
8NhCLCMCH
8 Indicator
Nh Amount of low cloud, or medium cloud if no low cloud present
(Table 5)
CL Form of low cloud (Table 13)
CM Form of medium cloud (Table 14)
CH Form of high cloud (Table 15)
SECTION 3
333
Regional Indicator
1snTxTxTx
1 Indicator
sn Sign of temperature (Table 8)
TxTxTx Maximum temperature 0600-1800 UTC in tenths of a degree
2snTnTnTn
2 Indicator
sn Sign of temperature (Table 8)
TnTnTn Minimum temperature 1800-0600 UTC in tenths of a degree
3EsnTgTg
3 Indicator
E State of ground without snow or measurable ice cover (Table 16)
sn Sign of temperature (Table 8)
TgTg Grass minimum temperature rounded to nearest whole degree
4E'sss
4 Indicator
E' State of ground with snow or measurable ice cover (Table 17)
sss Depth of snow (Table 18)
8NsChshs
8 Indicator
Ns Amount of individual cloud layer (Table 5)
C Form of cloud(Table 19)
hshs Height of base of cloud layer (Table 20) Up to four layers of
significant cloud can be reported (using 8NhChshs groups).
The rules for the selection
of significant cloud layers are: 1. The lowest layer of
any amount 2. The next lowest layer of 3 oktas (eighths) or more. 3.
The next lowest
layer of 5 oktas or more.
Any cumulonimbus cloud not already reported under 1, 2
or 3 above, regardless of amount. Clouds are reported
in order
of
ascending
height. Cumulonimbus cloud
reported under rule 4 above would be inserted between the other
groups at its correct height level - regardless of the
amount of
Cumulonimbus being reported.
9SpSpspsp 9 Indicator This group is included when necessary to
report special phenomena
SECTION 5
555 National indicator (This section is not sent
when there are no data to report)
1V'f'/V'f''f''
1 Indicator
V'V' Visibility in metres (reported when visibility is less than 100
m)
(f')f'f' Speed in knots of the maximum gust in the past hour (>33
kts)
2snTwTwTw
2 Indicator
sn Sign of temperature (Table 8)
TwTwTw Sea temperature in tenths of a degree
Code Tables Table
1: iR Indicator for inclusion or omission of precipitation data
Code
Figure Precipitation data are reported:Group 6RRRtR is:
1 in Section 1 included
2 in Section 3 included
3 in none of the two Sections 1 and 3 omitted (precipitation amount
=0)
4 in none of the two Sections 1 and 3 omitted (precipitation amount
not available)
Note: UK practice only, code figures 1,3 and 4 to be used
Table 2: ix Indicator for type of station operation (manned or automatic)and
for present and past weather
Code
Figure Type of station operation Group 7wwW1W2 or 7wawaWa1Wa2 is:
1 manned included
2 manned omitted (no significant phenomena to report)
3 manned omitted (not observed, data not available)
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