How Is a Weather Map Used

Wondering how is a weather map used? Make sure you know the answer before you venture too far from shore in a boat, or you could find yourself in a life-threatening situation.

Understand the Risks
Boaters use weather maps to determine possible dangers caused by weather. A storm that is not fatal on land may be fatal at sea, especially for small boats. Weather maps show fronts, cloud cover, air stability, moisture, rain and wind.

A front is a boundary between air masses. The air masses have different characteristics. These characteristics may be temperature, air pressure or humidity. When hot and cold air masses slam into each other, it creates thunderstorms. Boaters need to stay away from thunderstorms, especially severe thunderstorms, because of the occurrence of high winds, rough seas and hail.

The weather map shows where the front is at the current time and the direction the front is moving. This will tell you what areas you should avoid.

Clouds and Wind
A weather map also shows cloud cover. Cloud cover comes in various forms; the clouds could be high and innocent, or they could be dark clouds carrying rain. A boater will look at the clouds on the weather map, in conjunction with fronts and other conditions, to determine if a storm is going to be heavy. Heavy storms should always be avoided if you're in a small craft or if you're not experienced at handling rough weather on the water.

Weather radar measures the intensity of rain, and this information is included on the map. Radar energy is pointed through a cloud, creating an echo. The echo tells the viewer how intense the precipitation is. This information is presented via color codes, with green indicating light rain and orange, yellow or red indicating severe conditions.

You'll also find wind speed and direction on a weather map. This is particularly useful for sailboats. The wind is depicted using lines and triangles. A solid black triangle shows that the wind is at 50 knots. A full line means winds are at 10 knots, and a half line means that the wind is at 5 knots. The wind barbs have numbers on them. Adding the numbers on the wind barbs give you the wind speed for that location. 

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