Wind barbs and station plots

The wind barb

A wind barb is data first: a Point with windDirection (degrees true, the direction the wind blows from) and windSpeed (knots). Observations plot directly, with nothing drawn by hand.

metocFeature(MetocGraphicName.WindBarb, [[-97.5, 35.4]], {windDirection: 270, windSpeed: 65});

• The direction is drawn to the nearest 10°, and the speed with Table M-I's half barbs (5 kt), barbs (10 kt) and pennants (50 kt).
• No speed draws an X at the end of the shaft. No direction draws the plot circle only, as Table M-I says such a wind "is not displayed"; validateMetocFeature reports it.
• Barbs go on the left of the shaft north of the equator and on the right south of it, read from the station's own latitude, as the WMO and NWS station model draws them.
• The wind barb has no SIDC: 2525E keeps its draw rule in Table M-I but lists no entity for it, so metocSidc returns undefined rather than a code another system could not read back.

The station plot

MetocGraphicName.StationPlot lays Appendix M's own symbols around one station, as the WMO and NWS station model does. It is a Point with the barb's wind plus:

Property	Drawn
cloudCover	A cloud coverage symbol's name, as the plot circle (empty when missing)
temperature	Upper left
dewPoint	Lower left
weather	A weather or storm symbol's name, left of the circle
pressure	Sea-level pressure in hPa, upper right in three digits (1013.2 → 132)
pressureChange	In tenths of hPa, right of the circle (1.9 → 19)
pressureTendency	A pressure tendency symbol's name, after the change; it carries the sign

metocFeature(MetocGraphicName.StationPlot, [[-77.4, 38.9]], {
    windDirection: 320, windSpeed: 15,
    cloudCover: MetocGraphicName.CloudScattered,
    temperature: 18, dewPoint: 9,
    pressure: 1016.4, pressureChange: 1.2,
});

Anything missing is left out. Like the barb, a station plot has no SIDC. stationChoices() in @zaes/metoc/editor lists the symbols each picker should offer.