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7 - Indicator for weather group
ww - Present weather
"Present weather" shall describe the weather at time of observation or (where specifically mentioned) during the period of one hour immediately preceding it. For "Present weather" one does not take into account meteorological phenomena which has been experienced more than one hour before the observation
Use highest code figure applicable (except that 17 takes preference over 20 to 49 incl.)
00 - 49 No precipitation at ship at time of observation
00 -03 Change of sky in last hour
00 Cloud development not observed or not observable.
01 Clouds dissolving or becoming less developed.
02 State of sky on the whole unchanged.
03 Clouds generally forming or developing.
04 -09 Haze,dust,sand or moke
04 Visibility reduced by smoke,e.g.veldt or forest fire,industrial smoke,volcanic ash.
05 Haze.
06 Widespread dust in suspension in the air,not raised by wind at or near ship at time of observation.
07 Visibility reduced by blowing spray.
08 Dust devils within last hour.(not for marine use.)
09 Duststorm or sandstorm within sight at the time of observation or during preceding hour.
10 -12 Shallow fog or mist
10 Mist (visibility 1,000 metres or more).
11 Shallow fog in patches. [not deeper than 10 m at sea]
12 Shallow fog,more or less continuous. [not deeper than 10 m at sea]
13 -16 Phenomena within sight but not at station
13 Lightning visible,no thunder heard.
14 Precipitation not reaching the ground or surface of sea.
15 Precipitation beyond 5 km (2.7 n mile),reaching surface.
16 Precipitation within 5 km (2.7 n mile),reaching surface.
17 Thunder audible during the 10 minutes preceding the time of observation, but no precipitation at time of observation
18 -19 Phenomena within last hour or at time of observation
18 Squall(s) [at or within sight of ship]
19 Funnel cloud(s) (Tornado cloud or waterspout) [at or within sight of ship]
20 -29 Phenomena within last hour but not at time of observation
20 Drizzle (not freezing) or snow rains. [not falling in showers]
21 Rain (not freezing). [not falling in showers]
22 Snow. [not falling in showers]
23 Rain and snow,or ice pellets. [not falling in showers]
24 Drizzle or rain,freezing. [not falling in showers]
25 Shower(s) of rain.
26 Shower(s) of snow,or of rain and snow.
27 Shower(s) of hail,or of hail and rain.
28 Fog in the past hour but not at present (visibility was less than 1,000 m but is now 1,000 m or more).
29 Thunderstorm (with or without precipitation or lightning). See also 91-94.
30 -39 Duststorm,sandstorm,drifting or blowing snow
30 Duststorm or sandstorm,falling*,slight or moderate.
31 Duststorm or sandstorm,unchanging*,slight or moderate.
32 Duststorm or sandstorm,rising*,slight or moderate
33 Duststorm or sandstorm,falling*,severe.
34 Duststorm or sandstorm,unchanging*,severe.
35 Duststorm or sandstorm,rising*,severe.
36 Drifting snow,below eye level,slight or moderate.
37 Drifting snow,below eye level,heavy.
38 Blowing snow,above eye level,light or moderate.
39 Blowing snow,above eye level,heavy.
(*These terms refer to development during the preceding hour.)
40 -49 Fog at time of observation
40 Fog bank at a distance at the time of observation,but not at ship during last hour,the fog extending to a level above that of the observer. [visibility 1,000 m or more]
41 Fog in patches. [visibility less than 1,000 m]
42 Fog,thinning in last hour,sky discernible. [visibility less than 1,000 m]
43 Fog,thinning in last hour,sky not discernible. [visibility less than 1,000 m]
44 Fog,unchanging in last hour,sky discernible. [visibility less than 1,000 m]
45 Fog,unchanging in last hour,sky not discernible. [visibility less than 1,000 m]
46 Fog,beginning or thickening in last hour,sky discernible. [visibility less than 1,000 m]
47 Fog,beginning or thickening in last hour,sky not discernible. [visibility less than 1,000 m]
48 Fog,depositing rime,sky discernible. [visibility less than 1,000 m]
49 Fog,depositing rime,sky not discernible. [visibility less than 1,000 m]
50 -99 Precipitation at ship at time of observation
(The intensity of the precipitation reported is that at the actual time of observation.The term 'intermittent' indicates that either the precipitation began,or that there were breaks during the preceding hour,without presenting the character of a shower).
50 -59 Drizzle
50 Slight drizzle.Intermittent.[not freezing]
51 Slight drizzle.Continuous. [not freezing]
52 Moderate drizzle.Intermittent. [not freezing]
53 Moderate drizzle.Continuous. [not freezing]
54 Dense drizzle.Intermittent. [not freezing]
55 Dense drizzle.Continuous. [not freezing]
56 Freezing drizzle.Slight.
57 Freezing drizzle.Moderate or dense.
58 Drizzle and rain.Slight.
59 Drizzle and rain.Moderate or dense.
60 -69 Rain
60 Slight rain.Intermittent. [not freezing]
61 Slight rain.Continuous. [not freezing]
62 Moderate rain.Intermittent. [not freezing]
63 Moderate rain.Continuous. [not freezing]
64 Heavy rain.Intermittent. [not freezing]
65 Heavy rain.Continuous. [not freezing]
66 Freezing rain.Slight.
67 Freezing rain.Moderate or heavy.
68 Rain or drizzle and snow.Slight.
69 Rain or drizzle and snow.Moderate or heavy.
70 -79 Solid precipitation,not in shower
70 Slight fall of snowflakes.Intermittent.
71 Slight fall of snowflakes.Continuous.
72 Moderate fall of snowflakes.Intermittent.
73 Moderate fall of snowflakes.Continuous.
74 Heavy fall of snowflakes.Intermittent.
75 Heavy fall of snowflakes.Continuous.
76 Ice prisms. [with or without fog]
77 Snow rains. [with or without fog]
78 Isolated star-like snow crystals. [with or without fog]
79 Ice pellets.
80 -90 Showery precipitation.No thunder at time of observation or during preceding hour
80 Slight rain shower(s).
81 Moderate or heavy rain shower(s).
82 Violent rain shower(s).
83 Slight shower(s)of rain and snow.
84 Moderate or heavy shower(s)of rain and snow.
85 Slight snow shower(s).
86 Moderate or heavy snow shower(s).
87 Slight showers of snow pellets or small hail*.
88 Moderate or heavy showers of soft or small hail*.
89 Slight showers of hail*. [not associated with tunder]
90 Moderate or heavy showers of hail*. [not associated with thunder]
(*The hail may be accompanied by rain,snow,or both.)
91 -94 Thunderstorm* during the preceding hour but not at the time of observation
91 Slight rain. [precipitation occurring at time of observation]
92 Moderate or heavy rain. [precipitation occurring at time of observation]
93 Slight snow,or heavy rain and snow, mixed, or hail. [precipitation occurring at time of observation]
94 Moderate or heavy snow,or rain and snow,mixed,or hail. [precipitation occurring at time of observation]
95 -99 Thunderstorm at time of observation
95 Slight or moderate thunderstorm without hail, but with rain and/or snow [precipitation occurring at time of observation]
96 Slight or moderate thunderstorm with hail. [precipitation occurring at time of observation]
97 Heavy thunderstorm without hail, but with rain and/or snow. [precipitation occurring at time of observation]
98 Thunderstorm with dust or sandstorm.
99 Heavy thunderstorm with hail. [precipitation occurring at time of observation]
(*Thunder heard;lightning may or may not be seen.)
W1W2 - Past weather
The period covered by "Past weather" shall be: Six hours for observations at 0000, 0600, 1200 and 1800 UTC; Three hours for observations at 0300, 0900, 1500 and 2100 UTC; For other observation hours please consult your PMO, Offshore Adviser or Meteorological Service
0 Cloud covering half or less of sky throughout appropriate period.
1 Cloud covering half or less of the sky for part of appropriate period and more than half the sky for part of the period.
2 Cloud covering more than half of sky throughout appropriate period.
3 Sandstorm,duststorm or blowing snow. [visibility less than 1,000 metres]
4 Fog or thick haze. [visibility less than than 1,000 metres]
5 Drizzle.
6 Rain.
7 Snow,or rain and snow mixed.
8 Shower(s).
9 Thunderstorm(s),with or without precipitation.
The highest applicable figure should be selected. An exception is made, however, in cases where the precipitation etc. is confined to the past hour,and is sufficiently well indicated by the ww code figure.Two code figures are applicable to the weather during the appropriate period, the highest code figure is recorded under W1 and the next highest is recorded for W2 .If the weather has been the same throughout the period,the code figures for W1W2 will be the same.