104 MANUAL OF MARINE METEOROLOGICAL OBSERVATIONS 



CODE TABLE 6 



Symbol WW — Present weather 



= 00-49 NO PREaPITATION AT THE STATION AT THE TIME OF OBSERVATION 



): No PRECIPITATION, FOG, ICE FOG, DUSTSTORM, SANDSTORM, DRIFTING OR 

 BLOWING SNOW AT THE STATION (oR SHIP) AT THE TIME OF OBSERVATION, 

 EXCEPT FOR 09 AND 17, OR DURING THE PRECEDING HOUR. 



I Cloud development not observed ■] 



Clouds generally dissolving or becoming less Characteristic change of 

 developed > the state of sky during 



1 State of sky on the whole unchanged the past hour. 



I Clouds generally forming or developing J 



Visibility reduced by smoke, e.g., from 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 (or ship) at the time of observation. 



07 Dust or sand raised by wind at or near the station (or ship) at the time 

 of observation, but no well developed dust whirl(s) or sand whirl(s) 

 and no duststorm or sandstorm seen. 



08 Well developed dust whirl(s) or sand whirl(s) seen at or near the station 

 (or ship) within last hour, but no duststorm or sandstorm. 



09 Duststorm or sandstorm within sight of station (or ship) or at station 

 (or ship) at time of observation or during the last hour. 



10 Light fog, visibility 1,000 meters (1,100 yards) or more. 



11 Patches of ] Shallow fog or ice fog at the station (or ship) not deeper 



12 More or less I than about 2 meters (6K feet) on land or 10 meters 



continuous | (33 feet) at sea (visibility less than 1,000 meters (1,100 

 J yards)). 



13 Lightning visible, ho thunder heard. 



14 Precipitation within sight, but not reaching ground or surface of the sea. 



15 Precipitation within sight, reaching ground or surface of the sea, but 



distant [i.e., estimated to be more than 5 kilometers (3 miles) from 

 station (or ship)). 



16 Precipitation within sight, reaching ground or surface of the sea, near to 



but not at the station (or ship). 



17 Thunderstorm, but no precipitation at the time of observation. 



18 Squall (s) 1 within sight during the past 



19 Funnel cloud(s)* (tornado or waterspout)/ hour. 



20-29: Precipitation, fog or ICE fog or thunderstorm at the station 



(or ship) during the PRECEDING HOUR BUT NOT AT THE TIME OF 

 OBSERVATION. 



Drizzle (not freezing) or snow grains 



Rain (not freezing) 



Snow 



Rain and snow or ice pellets. (See fig. 79.) | 



Freezing drizzle or freezing rain 



Shower(s) of rain. 



Shower(s) of snow, or of rain and snow. 



Shower(s) of hail, or of hail and rain. 



Fog or ice fog (visibility less than 1,000 meters (1,100 yards)). 



Thunderstorm (with or without precipitation). 



Duststorm, sandstorm or drifting OR BLOWING snow. 



20 

 21 

 22 

 23 

 24 

 25 

 26 

 27 

 28 

 29 

 30-39: 

 30 



31 



32 



33 



34 



35 



36 

 37 

 38 

 39 

 40-49: 



40 



>not falling as showers. 



Slight or moderate duststorm or) j^ decreased during the preceding hour. 



sandstorm J e. f b 



Slight or moderate duststorm or\no appreciable change during the pre- 



sandstorm / ceding hour. 



Slight or moderate duststorm orlhas begun or increased during the pre- 



sandstorm 

 Severe du!5tstorm 



sandstorm 

 Severe duststorm 



sandstorm 

 Severe duststorm 



sandstorm 



/ ceding hour. 

 °'^|-has decreased during the preceding hour. 



""^mo appreciable change during preceding hour. 



[has begun or increased during the preceding hour. 



Slight or moderate drifting snow) Drifting snow 10 meters (33 ft.) or be- 

 Heavy drifting snow / low at sea. 



Slight or moderate blowing snowlBlowing snow above 10 meters (33 ft.) 

 Heavy blowing snow J at sea. 



Fog or ice fog at the time of observation (visibility less than 1,000 



meters (1,100 yards)). 

 Fog or ice fog at a distance at the time of observation, but not at the 



station (or ship) during the last hour, the fog extending to a level above 



that of the observer. 



