10 0 No change
21 1 Marked wind shift
32 2 Beginning or ending of marked turbulence
43 3 Marked temperature change (not with altitude)
54 4 Precipitation begins or ends
65 5 Change in cloud forms
76 6 For or ice fog bank begins or ends
87 7 Warm front
98 8 Cold front
109 9 Front, type not specified
1115 15 Missing value
12