isobars signify the air pressure, in millibars, at the ocean surface (1 mb = 1 hPa).
The red, purple and blue isotherms show the temperature at 2
m above the ocean surface. A blue line denotes sub-freezing conditions; a purple line denotes 0°C and; a red line denotes temperatures above freezing.
Wind speed is displayed in metres per second (
m/s).
The angle of the wind barb is indicative
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