Symbols

 Each circle represents a weather station. The circle at each station is empty if skies are clear. The circle is white if it’s cloudy. A line within the circle or a half-filled circle means "partly cloudy."
 * Blue lines are cold fronts  and red lines are warm fronts.
 * High  and Low Pressure Systems
 * A blue "H" means a center of high pressure (usually calm, sunny weather).
 * A red "L" means low pressure (which can mean storminess). Most fronts extend from low-pressure centers.
 * Cloud Cover **