INSTRUCTIONS TO MARINE METEOROLOGICAL OBSERVERS Ql 



Past weather (W). — This part of the message calls for a descrip- 

 tion of the state of the weather during the 6 hours preceding the 

 observation. The code table to be used in reporting "W" is given 

 below. 



Symbol W — Past weather 



Weather 



Fair (clear or slightly clouded) -.. 



Variable sky 



Mainly overcast.— - - 



Sandstorm or duststorm, or storm of drifting snow 



Fog or thick dust haze (visibility less than 1,000 meters [1,100 



yards]) 



Drizzle 



Rain. 



Snow or sleet 



Showers.. 



Thunderstorm 



Code 

 figures 



Should the type of weather undergo a complete change during the 

 interval in question, the figure chosen should be the one which de- 

 scribes the weather conditions existing before the change to the type 

 of weather that prevails at the hour of observation, so that "W" 

 and "ww" together give as complete a description as possible of the 

 weather in the time interval concerned. 



Should more than one figure of the "W" scale be applicable to the 

 past weather, the higher figure should be selected. When the past 

 weather has been characterized chiefly by the presence of broken 

 clouds, with showers occurring within sight of the ship, it is im- 

 portant that the figure 8 (showers) be sent in the message rather 

 than 1 (variable sky), even if no showers have passed directly over 

 the ship. In general, the occurrence of any form of precipitation 

 should be given preference in the report of past weather. 



jState of sea (S). — Instructions for the recording and coding of 

 observations of the state of the sea have been given on page 54. 



Character of sweM (K). — Instructions for the recording and cod- 

 ing of the character of the swell have been given on page 54. 



Direction from lohich sioell is moving (Dk). — Instructions for the 

 recording and coding of the direction of the swell have been given 

 on page 55. 



Ship^s course (ds). — The direction toward which the ship is mov- 

 ing is recorded and coded according to the scale 0-8, in which 1 = NE., 

 2 = E., etc. 



Symbol ds — Direction toward which ship is moving 



