The Small Craft Advisory
What is a “small craft advisory”, or a “small craft”, for that matter? What is the difference between an “advisory” and a “warning”? Anglers, boaters, guides and other captains here in the fabulous Florida Keys often ask these questions. I hope to provide some answers to these excellent questions in this article.
The U.S. National Weather Service marine weather warning program uses a multi-tiered concept to increase public awareness and promote a proper response to an impending hazardous marine weather event. This concept identifies four different types of weather messages beyond the routine, everyday marine forecasts: outlook, watch, warning and advisory.
An outlook indicates that a hazardous marine weather event may develop. It is intended to provide information to those who need considerable lead time to prepare for the event. Marine outlooks in the Florida Keys usually are issued within the
“Hazardous Weather Outlook” message, which is available online at:
A watch is used when the risk of a hazardous marine weather event has increased, but its occurrence, location, and/or timing is still uncertain. It is intended to provide enough lead time so those who need to set their plans in motion can do so. A typical marine weather “watch” in the Florida Keys will be associated with a gale, tropical storm, or hurricane.
A warning is used when a hazardous marine weather event is occurring, is imminent, or has a very high probability of occurrence. A warning is used for conditions posing a threat to life or property. Common marine weather “warnings” in the Florida Keys include the “Special Marine Warning” (issued for strong/severe thunderstorms or waterspouts) and the “Gale Warning” (sustained winds or frequent gusts of 34 knots or higher).
An advisory is used for less serious conditions that cause significant inconvenience and, if caution is not exercised, could lead to situations that may threaten life and/or property. The most common marine weather advisory in the Florida Keys is the “Small Craft Advisory”. Small craft advisory issuance thresholds vary by geographic region, based on expressed user needs specific to that region. However, in Florida and throughout the Gulf coast, Puerto Rico, and the Virgin Islands, a small craft advisory is issued for “sustained winds of 20 to 33 knots, and/or forecast seas of 7 feet or greater expected for more than 2 hours”. The wind and sea thresholds differ slightly, from South Carolina northward along the Atlantic coast, across the Great Lakes, and out west (including Alaska and the Pacific islands of Hawaii, Guam, and American Samoa). About 50–70 small craft advisories are issued in a typical year in the Florida Keys, with most small craft advisory events occurring during the windiest months of November, December, January, February, and March.
Finally, regular users of the Florida Keys “Coastal Waters Forecast” will notice a headline (“Small Craft Should Exercise Caution”) which is inserted when wind and/or sea conditions are expected to be just below the thresholds for small craft advisories (usually, sustained winds of 15 to 20 knots and seas of 6 feet).
You will notice that no precise definition of “small craft” is provided. This omission is the source of considerable discussion among weather forecasters and mariners. Nevertheless, any vessel that may be adversely affected by Small Craft Advisory criteria should be considered a small craft. Other considerations should include the experience of the vessel operator, and the type, design, and seaworthiness of the vessel. We recommend consulting one of the fine men and women of the U.S. Coast Guard Auxiliary or U.S. Sail and Power Squadron in the Florida Keys for additional information on obtaining free vessel safety exams or enrollment in a boating skills or seamanship class.
The unique orientation, terrain, currents, and surrounding water depths of the Florida Keys often result in dramatic differences in observed surface wind and sea state, depending on windward/leeward exposure, wind fetch, water depth, and other factors.
An experienced, weatherwise, and safety-minded captain is a valuable resource for the planning and execution of any voyage across the beautiful coastal waters adjoining the Florida Keys.
The National Weather Service in Key West, Coast Guard stations in Key West, Marathon, and Islamorada, and some marinas in the Florida Keys will raise a red pennant on the main flagpole upon issuance of a small craft advisory to alert mariners and passers-by of the marine weather situation. If you see the red pennant, be weather-ready, and stay safe!
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