SYNOP Code Form

SYNOP is the traditional WMO character-based code for the global exchange of meteorological data from a fixed land station.

The code form below conforms to WMO Regulations and is supplemented with regional requirements (Region 5 - South-West Pacific) and national practices (Australia). Some changes have been made to suit our local operations that are documented in the table below.

Code Form Description Requirements
MiMiMjMj message type identifier Always included and reported 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 is used as the station identifier.
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 prior to the time of the observation
mean wind speed (ff) in the 10 minutes prior to 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 prior to 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 when current lightning or past precipitation is detected. The group 7wwW1W2 may be manually included at other times. 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.
333 regional section identifier 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 24 hours to 00:00 UTC UTC		 Regional group. Always included at 00:00 UTC UTC. Reported as 0000 if the amount is zero or as //// if datum is unavailable.
555 national section identifier Only included if one or more national groups are reported.
1snTxTxTx group identifier (1)
indicator for sign of the temperature (sn)
maximum temperature (TxTxTx)		 National group specified by the BoM. To suit local operations, this group is included at 18:00 local time if datum is available.
2snTnTnTn group identifier (2)
indicator for sign of the temperature (sn)
minimum temperature (TnTnTn)		 National group specified by the BoM. Included at 09:00 local time if datum is available.
910fgfg group identifier (910)
highest wind gust (fgfg) in the 10 minutes prior to the time of the observation		 To suit local operations, this national group specified by the NWS is always included if datum is available.

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