At the station

Present weather and station models

What an observer records at the station, not what an app predicts.

A station model is a plot, not a prediction. Weather Prediction Center teaching pages place sky cover in the circle, wind on a barb that points to where the wind comes from, pressure as a three-digit code in tenths of a millibar, and a present-weather sign only when something is falling or the air is thick enough to cut the view. The barb is arithmetic: a pennant is 50 knots, a long barb 10, a short barb 5. Calm is the circle with no barb. None of that is a forecast icon. The present-weather sign belongs to the observing codes, the family of WMO code table 4677, which sorts current and recent conditions, type, and intensity. This line does not print all one hundred codes. It prints the frame, the wind, the sky, the pressure tendency, and the conditions people mix up with a phone icon. If you came from a forecast of rain, the rain page says how the plot differs. If you came from a front, that is the next line over.

The circle, the barb, and the number are one plot. Pulling the present-weather sign out and calling it the forecast is how a station report gets misread as a promise. The pages leave the plot in one piece. Visibility is written as a number on that same plot. It is not a second fog icon.

Start here. Station model. The station model is the whole plot. The other marks on this line are pieces of it.

1. 1
   
   Station modelThe whole observation plot. Sky in the circle, wind on the barb, weather only if something is falling or the air is thick.
2. 2
   
   Present weatherThe sign plotted beside a station when weather is occurring. Not a forecast icon, and not all one hundred codes.
3. 3
   
   Sky coverThe filled circle on a station model. More ink means more of the sky was covered.
4. 4
   
   Wind barbStaff, barbs, and pennants: where the wind came from, and how fast. Not a forecast wind icon.
5. 5
   
   Calm windA circle and no staff. The wind at the station was calm. Not a clear-sky icon.
6. 6
   
   VisibilityThe reported seeing distance at the station. A number, not a forecast fog icon.
7. 7
   
   Pressure tendencyHow pressure changed in the last three hours. Not the sea-level pressure code, and not a front.
8. 8
   
   Funnel cloudAn observing category for a funnel. Not a tornado emoji, and not a thunderstorm icon by itself.
9. 9
   
   Dust stormDust storm or sandstorm as weather that is happening. Not the milder dust forecast, and not haze.
10. 10
    
    RainA forecast icon for rain expected in a period. Not a shower, not drizzle, and not the station-model sign.
11. 11
    
    DrizzleA forecast icon for very small, close-set drops. Not light rain, and not mist.
12. 12
    
    SnowA forecast icon for expected snow. Not a snow shower, not sleet, and not a snowman.
13. 13
    
    HailA forecast icon for hail. Not snow, and not sleet.
14. 14
    
    ThunderstormA forecast icon for thunder and lightning. Not a decorative bolt, and not ordinary rain.
15. 15
    
    FogA forecast icon for fog. Not mist, not haze, and not the fog character.
16. 16
    
    HazeA forecast icon for haze. Not fog, not mist, and not smoke.