A SYNOPTIC weather report is issued after every three hours. It is coded numerically and contains information about the weather of a particular weather station/area. It is coded as FM-12 by WMO. It contains weather information for the preceding three hours. Synop is issued at synoptic hours. Synoptic hours are 0000Z, 0300Z, 0600Z, 0900Z, 1200Z,1500Z, 1800Z and 2100Z.These are in UTC timings. It has a proper structure and format to report weather information in coded form. In this article, we will only consider the rainfall reporting codes in SYNOP. To report rain in SYNOP follow the following instructions carefully.
A rainfall amount of 3 hrs (60007) is issued in every SYNOP in Section 3.
Rainfall of 24 hours ( 70000) is issued in SYNOP of 0300 UTC in section 3.
Rainfall of 6 hours (60001) is reported in SYNOP of 0600 UTC in Section 1.
Rainfall of 12 hours (60002) is reported in SYNOP of 1200 and 0000 UTC in Section 1.
Rainfall of 18 hours (60003) is reported in SYNOP of 1800 UTC in section 1.
Rainfall at 0000Z:
At 0000Z we have to report rain of the preceding 12 hours in the 60002 group in section 1 and rainfall of the preceding three hours 60007 in section 3.
Example: If there is a rainfall of 4 mm from 1800Z to 2100Z and 2 mm from 2100Z to 0000Z. In 0000Z SYNOP we will have two rain groups.60062 in section 1 for 12 hours of rainfall and 60023 in section 3 for the preceding three hours of rainfall.
Rainfall at 0300Z:
At 0300Z we have to report rain of the preceding 24 hours in the 70000 group in section 3 and also rainfall of the preceding three hours 60007 in section three.
Example: If there is a rainfall of 4 mm from 1800Z to 2100Z and 2 mm from 2100Z to 0000Z. In 0300Z SYNOP we will have two rain groups.60003 in section 3 for 3 hours of rainfall (As there is zero rainfall in the preceding three hours) and 70060 in section 3 for the preceding three 24 hours of rainfall.
Rainfall at 0600Z:
At 0600Z we have to report rain of the preceding 06 hours in the 60001 group in section 1 and rainfall of the preceding three hours 60007 in section three.
Example: If there is a rainfall of 4 mm from 0000Z to 0300Z and 2 mm from 0300Z to 0600Z. In 0600Z SYNOP we will have two rain groups.60061 in section 1 for 12 hours of rainfall and 60023 in section 3 for the preceding three hours of rainfall.
Rainfall at 0900Z:
At 0900Z only rainfall of the preceding three hours is reported in the 60007 group in section 3.
Rainfall at 1200Z:
At 1200Z we have to report rain of the preceding 12 hours in the 60002 group in section 1 and rainfall of the preceding three hours 60007 in section three.
Example: If there is a rainfall of 4 mm from 0000Z to 0300Z and 2 mm from 0300Z to 0600Z. In 1200Z SYNOP we will have two rain groups.60062 in section 1 for 12 hours of rainfall and 60003 in section 3 for the preceding three hours of rainfall.
Rainfall at 1500Z:
At 1500Z only rainfall of the preceding three hours is reported in the 60007 group in section 3.
Rainfall at 1800Z:
At 1800Z we have to report rain of the preceding 18 hours in the 60003 group in section 1 and rainfall of the preceding three hours 60007 in section three.
Example: If there is a rainfall of 4 mm from 0000Z to 0300Z and 2 mm from 0300Z to 0600Z. In 1800Z SYNOP we will have two rain groups.60063 in section 1 for 18 hours of rainfall and 60003 in section 3 for the preceding three hours of rainfall.
Rainfall at 2100Z:
At 2100Z only rainfall of the preceding three hours is reported in the 60007 group in section 3.
Important Note:
In all rain groups starting from 6, the first and last digits are indicators i.e in 60007 6 and 7 are indicators. Rainfall information is coded in 000 between 6 and 7. 000 is in rounded whole number. If there is 1.2mm of rain in three hours it is reported as 60017.
Rainfall Code
Trace 69907
0.1 mm 69917
0.2mm 69927
. .
. .
0.9 69997
In 24 hours rainfall group i.e in 70000 last digit is a number after decimal i.e
trace 79999
Rainfall Code
0.1mm 70001
0.2mm 70002
5mm 70050
5.6mm 70056
