Hurricane warnings

Stay safe when storms threaten

During hurricane season, mariners should monitor NOAA radio, the National Hurricane Center’s website and other sources of public weather forecasts as well as watch for warning signs of an approaching storm.

Warning signs

Swells: Abnormally large and far apart swells with a period of 10 to 15 seconds may indicate the approach of a tropical storm or hurricane.

Clouds and barometer: A series of cloud and barometer changes can also indicate a storm’s approach.

• As a hurricane approaches, cirrus clouds appear, much as they would in a middle-latitude warm front.
• The barometer starts a long, slow fall.
• Cirrus formations thicken, forming a veil of cirrostratus clouds; altostratus clouds form beneath the cirrostratus clouds; and light rain begins.
• The barometer plunges, and wind gusts increase.
• Dark cumulonimbus clouds appear, and rainsqualls become more frequent.

Taking action

Inshore boaters should check moorings, line and gear. If you intend to move the boat to a safer location, plan ahead and act well before the storm arrives. If you’re staying put, be aware of your marina’s storm or hurricane procedures. Never stay on board.

Offshore boaters need to do some quick analysis:

• Locate the storm’s center by applying Buys Ballot’s Law,According to Buys Ballot’s Law, if you are in the Northern Hemisphere facing the wind and you hold your right arm out to the side, the low pressure will be slightly behind your outstretched arm—15 degrees on the water, 30 on land. adjusting for higher winds.
• Based on the boat’s speed and capabilities, you must decide whether a safe mooring or harbor can be reached, using the 1-2-3 rule to calculate the storm’s closest point of approach.
• When planning a course, you should never pick a course that will take the vessel across the projected storm track.
• If forced to remain offshore, you should try to get to the storm’s navigable semicircleIn the northern latitudes, the navigable semicircle is on the storm’s left side. Even though the winds aren’t as strong there, they and the seas remain extremely dangerous. and avoid the storm’s eye, which would mean crossing the eye wall where winds are strongest. Seas in the eye are confused, and mountainous 50-footers are common.

To learn more, take the Weather course at a squadron near you.

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