United States Storm Warning Signals

Requirement for Surface Weather Observation by Ships

Military Requirements for Petty Officer 3rd Class
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5-16 Figure 5-4.—An installed anemometer. Figure 5-5.—Synchro repeater showing relative wind velocity and direction. United States Storm Warning Signals.—The combinations of flags and pennants, as shown in figure 5-6, are hoisted at the National Weather Service and other shore stations in the United States to indicate the presence or future presence of unfavorable winds. The means of the various displays are as follows: Small craft warning: One red pennant displayed by day and a red light over a white light at night to indicate that winds up to 38 miles per hour (33 knots) and/or sea conditions dangerous to small craft operations are forecast for the area. Gale warning: Two red pennants displayed by day and a white light above a red light at night to indicate that winds ranging from 39 to 54 miles per hour (34 to 47 knots) are forecast for the area. Storm warning: One square red flag with a black center displayed during daytime and two vertical red lights at night to indicate that winds 55 miles per hour (48 knots) and above, no matter how high the speed, are forecast for the area. If the winds are associated with a tropical cyclone (hurricane), the storm-warning display indicates that winds within the range of 55 to 73 miles per hour (48 to 63 knots) are forecast. Hurricane warning (displayed only in connection with a tropical cyclone or hurricane): Two square red flags with black centers displayed at daytime and a white light between two vertical red lights at night to indicate that winds 74 miles per hour (64 knots) and above are forecast for the area. Timely and accurate weather observations are basic to the development of meteorological and oceanographic forecasts in support of fleet operations. Since the U.S. Navy may be committed to operations anywhere in the world, total global observations of meteorological and oceanographic conditions are required. Ships in port are required to make regular weather observations and to report by electronic means unless there is a nearby U.S. manned weather-reporting activity. In-port weather observations and reports of guard ship arrangements may be used for groups of ships at the discretion of the senior officer present. In such instances, the weather logs of exempted ships should bear a notation of the guard ship(s) and effective dates and times. Table 5-1 provides the minimum requirements for reporting weather observations by Navy ships.

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