KEYNOTES ON METEOROLOGICAL OBSERVATIONS 

 1. Prevailing weather conditions. 



(a) Type: WS - 



Water spout 



TH - 



Thunderstorm 



FD - 



Freezing drizzle 



F - 



Fog 



SS - 



Snow shower 



RS - 



Rain shower 



H - 



Hail 



S - 



Snow 



R - 



Rain 



D - 



Drizzle 



K - 



Haze or smoke 



(b) Intensity: 



(+) - Unusually 



(-) - Mild conditions 



2. Pressure trends. 



(a) First number indicates characteristic of change: 



- Increasing then decreasing. 



1 - Increasing then steady or increasing more slowly. 



2 - Increasing either steady or unsteady. 



3 - Decreasing or steady then increasing; or increasing 



then increasing more rapidly. 



4 - Steady. 



5 - Dacreasing then increasing. 



6 - Decreasing then steady or decreasing more slowly. 



7 - Decreasing steady or unsteady. 



8 - Steady or increasing then decreasing; or decreasing 



then decreasing more slowly. 



(b) The next two numbers indicate code of the amount of change in last 3 

 hours ; higher numbers indicate more change : 



GO = 0.0 millibars 



51 = 5.1 millibars 



100 = 10.0 millibars 



200 = 20.0 millibars 



3. WFG: A (+) symbol is entered if the windspeed varies more than 5 meters 



per second. 



4. VAR: The peak value of the windspeed is entered under (VAR) when the peak 



value exceeds the value of the windspeed by at least 5 meters per 

 second. 



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