United States Storm Warning Signals

Table 8-1. Requirement for Surface Weather Observation by Ships

Military Requirements for Petty Officers Third and Second Class
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The upper dial of the repeater is graduated in 10-degree intervals and shows the relative direction from which the wind is blowing. In this illustration the direction is about 287 . The lower dial indicates the relative wind speed (true wind speed when the ship is stationary). The wind-speed dial in the illustration shows about 87 knots. This reading means that the force exerted by 87 knots of wind is whirling the anemometer propeller. When you use an installed anemometer, always compare the readings observed with the wind conditions as they appear outside. If two anemometers are installed, ensure that the windward anemometer is used. United States Storm Warning Signals.—The combinations of flags and pennants, as shown in figure 8-6, 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. 8-17 MRP3F0504 Figure 8-4. An installed anemometer. WIND DIRECTION 0 330 30 300 60 90 12 270 240 210 180 150 WIND SPEED KNOTS 0 90 10 20 30 80 70 60 50 40 MRP3F0505 Figure 8-5. Synchro repeater showing relative wind velocity and direction.

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