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