SYNOP Code Form

SYNOP is the traditional WMO character-based code for the exchange of meteorological data from a fixed land station. The code form presented below conforms to WMO Regulations and is supplemented by regional requirements (Region 5 - South-West Pacific) and national practices (Australia). Some sections of the code form are omitted because they are not relevant to our station, namely: Section 2, maritime data for global exchange from a sea or coastal station; and Section 4, clouds with a base below station level for national use.

Some minor changes to the reporting requirements have been made to suit our local operations, the details of which are documented below. View our hourly synop reports.

Section 0 Data for reporting message type, station identification, date, time and units of wind speed used
MiMiMjMj message type identifier Always included as AAXX.
YYGGiW date of the observation UTC (YY)
hour of the observation UTC (GG)
indicator for source of wind speed (iW)		 Always included.
IIiii block number (II) relates to the geographical area
station number (iii) allocated by the national meteorological agency		 Always included. To suit local operations, F0878, the MADIS identifier assigned to this PWS acts as the de facto station identifier.
Section 1 Data for global exchange
iRixhVV indicator for inclusion of rainfall data (iR)
indicator for station operation (ix)
height AGL of the base of lowest cloud (h)
horizontal visibility (VV)		 Always included.
Nddff total amount of cloud (N)
mean wind direction (dd) in the 10 minutes ending at the time of the observation
mean wind speed (ff) in the 10 minutes ending at the time of the observation		 Always included.
1snTTT group identifier (1)
indicator for sign of the temperature (sn)
dry bulb temperature (TTT)		 Only included if datum is available.
2snTdTdTd group identifier (2)
indicator for sign of the temperature (sn)
dew point temperature (TdTdTd)		 Only included if datum is available.
3PoPoPoPo group identifier (3)
station level pressure (PoPoPoPo)		 Only included if datum is available.
4PPPP group identifier (4)
mean sea level pressure (PPPP)		 Only included if datum is available.
5appp group identifier (5)
indicator for pressure trend (a)
pressure tendency (ppp) in the 3 hours ending at the time of the observation		 Included at 00:00 UTC and then every 3 hours if datum is available.
6RRRtR group identifier (6)
amount of rainfall (RRR)
indicator for period of rainfall (tR)		 To suit local operations the group is always included. RRR is encoded as 000 if the amount is zero or /// if the datum is unavailable.
7wwW1W2 or 7wawaWa1Wa2 group identifier (7)
type of present weather (ww or wawa) at or just prior to the time of the observation
type of past weather (W1 and W2 or Wa1 and Wa2) since the last observation		 To suit local operations, 7wawaWa1Wa2 is included only if current lightning and or past precipitation are detected. The group 7wwW1W2 may be included at other times by manual intervention. Element ix indicates the form of the included group.
8NhCLCMCH group identifier (8)
amount of lowest cloud (Nh)
type of low level cloud (CL)
type of middle level cloud (CM)
type of high level cloud (CH)		 Only included if data are available. The amount of lowest cloud refers to low or middle cloud only, and is reported as 0 if there is only high cloud.
Section 3 Data for regional exchange
333 regional section identifier (333) Only included if one or more regional groups are reported.
1snTxTxTx group identifier (1)
indicator for sign of the temperature (sn)
maximum temperature (TxTxTx)		 Regional group. Included at 12:00 UTC if datum is available.
2snTnTnTn group identifier (2)
indicator for sign of the temperature (sn)
minimum temperature (TnTnTn)		 Regional group. Included at 00:00 UTC if datum is available.
6RRRtR group identifier (6)
amount of rainfall (RRR)
indicator for period of rainfall (tR)		 Regional group. Included at 00:00 UTC then every 6 hours if rainfall is recorded or as /// if datum is unavailable.
7R24R24R24R24 group identifier (7)
amount of rainfall (R24R24R24R24) recorded in the past 24 hours		 Regional group. Always included at 00:00 UTC. Reported in tenths of a mm, or 0000 if the amount is zero or as //// if datum is unavailable.
910fgfg group identifier (9)
indicator for highest gust in the 10 minutes ending at the time of the observation (10)
highest wind gust (fgfg)		 Regional group. To suit local operations this supplementary information group is always included if datum is available.
Section 5 Data for national use
555 national section identifier (555) Only included if one of the following national groups is reported.
1snTxTxTx group identifier (1)
indicator for sign of the temperature (sn)
maximum temperature (TxTxTx)		 National group specified by Australia. To suit local operations this group is included at 18:00 local time (instead of 15:00) if datum is available.
2snTnTnTn group identifier (2)
indicator for sign of the temperature (sn)
minimum temperature (TnTnTn)		 National group specified by Australia. Included at 09:00 local time if datum is available.

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