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Code Table 4 |
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(WMO Code 4677) |
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Symbol ww = Present Weather |
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00-49: No precipitation at the station at the time of observation. |
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00-19: No precipitation, fog, ice fog (except for 11 and 12), duststorm, |
drifting or blowing snow at the station at the time of observation |
or, except for 09 and 17, during the preceding hour. |
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00-03: No meteors except photometeors. Characteristic change of the state |
of sky during past hour. |
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00 Cloud development not observed or not observable. |
01 Clouds generally dissolving or becoming less developed. |
02 State of sky on the whole unchanged. |
03 Clouds generally forming or developing. |
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04-09: Haze, dust, sand or smoke. |
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04 Visibility reduced by smoke, e.g., veldt or forest fires, industrial |
smoke or volcanic ashes. |
05 Haze. |
06 Widespread dust in suspension in the air, not raised by wind at or |
near the station at the time of observation. |
07 Dust or sand raised by wind at or near the station at the time of |
observation, but no well developed dust whirl(s) or sand whirl(s), and |
no duststorm or sandstorm seen: or, in the case of ships, blowing |
spray at the station. |
08 Well developed dust whirl(s) or sand whirl(s) seen at or near the |
station during the preceding hour, or at the time of observation, but |
no duststorm or sandstorm. |
09 Duststorm or sandstorm within sight at the time of observation or at |
station during the preceding hour. |
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10 Light fog. (Vis. 1,100 yds. or more) 1 |
11 Patches of shallow fog or ice fog at the station, whether on land or |
sea, not deeper than about 6 feet on land or 33 feet at sea. |
(Apparent vis. less than 1,100 yds.) |
12 More or less continuous shallow fog or ice fog at the station, whether |
on land or sea, not deeper than about 6 feet on land or 33 feet at sea. |
(Apparent vis. less than 1,100 yds.) |
13 Lightning visible, no thunder heard. |
14 Precipitation within sight, but not reaching the ground or the surface |
of the sea. |
15 Precipitation within sight, reaching the ground or the surface of the |
sea, but distant (i.e., estimated to be more than 3.1 miles) from the |
station. |
16 Precipitation within sight, reaching the ground or the surface of the |
sea near to but not at the station. |
17 Thunderstorm, but no precipitation at the time of observation. |
18 Squalls at or within sight of the station during the preceding hour |
or at the time of observation. |
19 Funnel cloud(s) (i.e., tornado cloud or waterspout) at or within sight |
of the station during the preceding hour or at the time of observation. |
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9/14/73 30 Rev 2 |
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Code Table 4 |
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(continued) |
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20-29: Precipitation, fog, ice fog or thunderstorm at the station during the |
preceding hour but not at the time of observation. |
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20-24: Not falling as showers. |
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20 Drizzle (not freezing) or snow grains. |
21 Rain. |
22 Snow. |
23 Rain and snow or ice pellets (type a). |
24 Freezing drizzle or freezing rain. |
25 Shower(s) of rain. |
26 Shower(s) of snow, or of rain and snow. |
27 Shower(s) of hail, or of rain and hail (3). |
28 Fog or ice fog. (Vis. less than 1,100 yds.). |
29 Thunderstorm (with or without precipitation). |
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30-39: Duststorm, sandstorm, drifting or blowing snow. |
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30 Slight or moderate duststorm or sandstorm, has decreased during the |
preceding hour. |
31 Slight or moderate duststorm or sandstorm, no appreciable change |
during the preceding hour. |
32 Slight or moderate duststorm or sandstorm, has begun or has increased |
during the preceding hour. |
33 Severe duststorm or sandstorm, has decreased during the preceding hour. |
34 Severe duststorm or sandstorm, no appreciable change during the |
preceding hour. |
35 Severe duststorm or sandstorm, has begun or has increased during the |
preceding hour. |
36 Slight or moderate drifting snow, generally low. (Less than 6 ft.) |
37 Heavy drifting snow, generally low. (Less than 6 ft.) |
38 Slight or moderate blowing snow, generally high. (6 ft. or more.) |
39 Heavy blowing snow, generally high. (6 ft. or more.) |
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40-49: Fog or ice fog at the time of observation. (Vis. less than 1,100 yds.) |
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40 Fog or ice fog at a distance at the time of observation, but not at the |
station during the preceding hour, the fog or ice fog extending to a |
level above that of the observer. |
41 Fog or ice fog in patches. |
42 Fog or ice fog, sky discernible, has become thinner during the |
preceding hour. |
43 Fog or ice fog, sky not discernible, has become thinner during the |
preceding hour. |
44 Fog or ice fog, sky discernible, no appreciable change during the |
preceding hour. |
45 Fog or ice fog, sky not discernible, no appreciable change during the |
preceding hour. |
46 Fog or ice fog, sky discernible, has begun or has become thicker during |
the preceding hour. |
47 Fog or ice fog, sky not discernible, has begun or has become thicker |
during the preceding hour. |
48 Fog, depositing rime, sky discernible. |
49 Fog, depositing rime, sky not discernible. |
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9/14/73 31 Rev 2 |
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Code Table 4 |
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(continued) |
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50-59: Precipitation at the station at the time of observation. |
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50-59: Drizzle |
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50 Drizzle, not freezing, intermittent, slight at time of observation. |
51 Drizzle, not freezing, continuous, slight at time of observation. |
52 Drizzle, not freezing, intermittent, moderate at time of observation. |
53 Drizzle, not freezing, continuous, moderate at time of observation. |
54 Drizzle, not freezing, intermittent, heavy (dense) at time of |
observation. |
55 Drizzle, not freezing, continuous, heavy (dense) at time of |
observation. |
56 Drizzle, freezing, slight. |
57 Drizzle, freezing, moderate or heavy (dense). |
58 Drizzle and rain, slight. |
59 Drizzle and rain, moderate or heavy. |
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60-69: Rain |
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60 Rain, not freezing, intermittent, slight at time of observation. |
61 Rain, not freezing, continuous, slight at time of observation. |
62 Rain, not freezing, intermittent, moderate at time of observation. |
63 Rain, not freezing, continuous, moderate at time of observation. |
64 Rain, not freezing, intermittent, heavy (dense) at time of |
observation. |
65 Rain, not freezing, continuous, heavy (dense) at time of |
observation. |
66 Rain, freezing, slight. |
67 Rain, freezing, moderate or heavy. |
68 Rain or drizzle and snow, slight. |
69 Rain or drizzle and snow, moderate or heavy. |
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70-79: Solid precipitation not in showers |
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70 Intermittent fall of snow flakes, slight at time of observation. |
71 Continuous fall of snow flakes, slight at time of observation. |
72 Intermittent fall of snow flakes, moderate at time of observation. |
73 Continuous fall of snow flakes, moderate at time of observation. |
74 Intermittent fall of snow flakes, heavy (dense) at time of observation. |
75 Continuous fall of snow flakes, heavy (dense) at time of observation. |
76 Ice prisms (with or without fog). |
77 Snow grains (with or without fog). |
78 Isolated starlike snow crystals (with or without fog). |
79 Ice pellets (type a) (sleet, U.S. definition). |
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80-99: Showery precipitation, or precipitation with current or recent |
thunderstorm. |
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80 Rain shower(s), slight. |
81 Rain shower(s), moderate or heavy. |
82 Rain shower(s), violent. |
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9/14/73 31a Rev 2 |
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Code Table 4 |
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(continued) |
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83 Shower(s) of rain and snow mixed, slight. |
84 Shower(s) of rain and snow mixed, moderate or heavy. |
85 Snow shower(s), slight. |
86 Snow shower(s), moderate or heavy. |
87 Shower(s) of snow pellets, or ice pellets (type b) with or without rain |
or rain and snow mixed, slight. |
88 Shower(s) of snow pellets, or ice pellets (type b) with or without rain |
or rain and snow mixed, moderate or heavy. |
89 Shower(s) of hail (3), with or without rain or rain and snow mixed, not |
associated with thunder, slight. |
90 Shower(s) of hail (3), with or without rain or rain and snow mixed, not |
associated with thunder, moderate or heavy. |
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91-94: Thunderstorm during the preceding hour but not at time of observation. |
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91 Slight rain at time of observation. |
92 Moderate or heavy rain at time of observation. |
93 Slight snow or rain and snow mixed or hail (3) at time of observation. |
94 Moderate or heavy snow or rain and snow mixed or hail at time of ob- |
servation. |
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95-99: Thunderstorm at time of observation. |
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95 Thunderstorm, slight or moderate, without hail (3) but with rain and/or |
snow at time of observation. |
96 Thunderstorm, slight or moderate, with hail (3) at time of observation. |
97 Thunderstorm, heavy, without hail (3), but with rain and/or snow at |
time of observation. |
98 Thunderstorm combined with duststorm or sandstorm at time of observa- |
tion. |
99 Thunderstorm, heavy with hail (3) at time of observation. |
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1 The U.S. term, "light fog" is synonymous with the European term "mist". |
2 Refers to "hail" only. |
3 Refers to snow pellets, ice pellets (type b), and hail. |
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NOTE - With respect to precipitation, "at the station" means "at the point |
where the observation is normally taken." |
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| Updated 22 December 2005 |