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