SYNOP Code Form
SYNOP is the traditional WMO character-based code for the global exchange of land-based meteorological data for use on synoptic charts and in the preparation of forecasts and warnings. The code form is instantly recognisable, easily understood and with practice can be manually coded and decoded.
The code form described below is automatically generated each hour and displayed on our Weatherwall. This version closely conforms to the international standards defined by WMO, and supplemented by regional requirements (Asia) and national practices (Australia). The changes reflect our unique situation and local requirements.
| Code Form | Description | WMO Regulations & Local Requirements |
|---|---|---|
| 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, for our purposes the combination of special use block number 69 and vacant station number 259 were chosen |
| iRiXhVV | indicator for inclusion of rainfall data (iR) indicator for station operation (iX) height of the base of lowest cloud (h) either low or middle level cloud horizontal visibility (VV) |
always included |
| Nddff | total amount of cloud (N) mean wind direction (dd) in the 10 minutes prior to observation time mean wind speed (ff) in the 10 minutes prior to observation time |
always included |
| 1snTTT | group identifier (1) indicator for sign of the temperature (sn) dry bulb temperature (TTT) |
always included if datum is available |
| 2snTdTdTd | group identifier (2) indicator for sign of the temperature (sn) dew point temperature (TdTdTd) |
always included if datum is available |
| 4PPPP | group identifier (4) mean sea level pressure (PPPP) |
always included if datum is available |
| 5appp | group identifier (5) indicator for pressure trend (a) pressure tendency (ppp) in the 3 hours prior to observation time |
always included if datum is available |
| 6RRRtR | group identifier (6) amount of rainfall (RRR) indicator for period of rainfall (tR) |
always included |
| 7wwW1W2 | group identifier (7) type of present weather (WW) at or just prior to observation time type of past weather (W1 and W2) typically in the past 3 hours |
always included if data are available |
| 8NhCLCMCH | group identifier (8) amount of lowest cloud (Nh) either low or middle level cloud type of low level cloud (CL) type of middle level cloud (CM) type of high level cloud (CH) |
always included if data are available |
| 333 | regional section identifier | only included if a regional group is available |
| 5EEEie | group identifier (5) amount of evaporation (EEE) recorded in the 24 hours to 09:00 local time indicator for evaporation instrumentation (ie) |
regional group, included at 00:00 UTC if datum is available |
| 55SSS | group identifier (55) duration of sunshine (SSS) recorded yesterday |
regional group, included at 00:00 UTC if datum is available |
| 7R24R24R24R24 | group identifier (7) amount of rainfall (R24R24R24R24) recorded in the 24 hours to 00:00 UTC |
regional group, always included at 00:00 UTC |
| 555 | national section identifier | only included if a national group is available |
| 1snTxTxTx | group identifier (1) indicator for sign of the temperature (sn) maximum temperature (TxTxTx) recorded between 09:00 to 18:00 local time |
national group specified by Australia, for our purposes it shall be reported at 18:00, 19:00 and 20:00 local time if datum is available |
| 2snTnTnTn | group identifier (2) indicator for sign of the temperature (sn) minimum temperature (TnTnTn) recorded in the 24 hours to 09:00 local time |
national group specified by Australia, for our purposes it shall be reported at 09:00, 10:00 and 11:00 local time if datum is available |
| 910fgfg | group identifier (910) highest wind gust (fgfg) in the 10 minutes prior to observation time |
national group specified by the USA, for our purposes it shall always be reported if datum is available |
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