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 SYNOP described below, which is computer generated each hour for nostalgic reasons and personal use, closely conforms to the latest international standards defined by WMO and supplemented with regional requirements (Asia) and national practices (Australia). Some variations to the code form were necessary to reflect our stand-alone status and to meet our specific requirements concerning data reported in the national groups.

Code Form Description Requirements
MiMiMjMj message type identifier - AAXX is the prescribed identifier for SYNOP always included
YYGGiW date (YY) and hour (GG) UTC of the observation
indicator for source of wind speed (iW)
always included
IIiii station identifier - 5 digit numeric issued by the national meteorological agency always included, reported as TRUGWX for our purposes
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)
dry bulb temperature (TTT)
indicator for sign of the temperature (sn)
always included
2snTdTdTd group identifier (2)
dew point temperature (TdTdTd)
indicator for sign of the temperature (sn)
always included
4PPPP group identifier (4)
mean sea level pressure (PPPP)
always included
5appp group identifier (5)
pressure tendency (ppp) in the 3 hours prior to observation time
indicator for pressure trend (a)
always included
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
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
333 regional section identifier only included if a regional group is reported
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 reported
55SSS group identifier (55)
duration of sunshine (SSS) recorded yesterday between sunrise to sunset
regional group, included at 00:00 UTC if datum is reported
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 reported
1snTxTxTx group identifier (1)
maximum temperature (TxTxTx) recorded between 09:00 to 18:00 local time
indicator for sign of the temperature (sn)
national group specified by Australia, included for our purposes at 18:00, 19:00 and 20:00 local time if datum is reported
2snTnTnTn group identifier (2)
minimum temperature (TnTnTn) recorded in the 24 hours to 09:00 local time
indicator for sign of the temperature (sn)
national group specified by Australia, included for our purposes at 09:00, 10:00 and 11:00 local time if datum is reported
910fgfg group identifier (910)
highest wind gust (fgfg) in the 10 minutes prior to observation time
national group specified by the USA, always included for our purposes if datum is reported

back ]