The wind radii information contained in the tropical cyclone forecast/advisory takes a bit of decoding. We'll take the first forecast in the example forecast/advisory and work through it. FORECAST VALID 24/1800Z 21.9N  78.1W MAX WIND  65 KT...GUSTS  80 KT 64 KT... 30NE   0SE   0SW   0NW 50 KT...100NE 100SE  30SW  30NW 34 KT...135NE 125SE  75SW 125NW The first line FORECAST VALID 24/1800Z 21.9N  78.1W says that the forecast is valid on the 24th day of the month at 1800Z (2 p.m. EDT) and then gives the forecasted latitude and longitude of the storm's center (21.9N  78.1W). The second line MAX WIND  65 KT...GUSTS  80 KT gives the predicted maximum sustained wind speed (65 kt or 75 mph) and the peak gust expected (80 kt or 92 mph). The third line 64 KT... 30NE   0SE   0SW   0NW tells how far from the center of the storm the 64 kt (74 mph, or hurricane-force) winds extend in the northeast, southeast, southwest, and northwest directions. The distance is given in nautical miles (abbreviated NM; 1 NM equals 1.15 statute miles). So in the northeast direction, the hurricane-force winds extend out 30 NM, but there are no hurricane-force winds in any of the other directions. The fourth and fifth lines 50 KT...100NE 100SE  30SW  30NW 34 KT...135NE 125SE  75SW 125NW give the same information for the 50 kt (58 mph) and 34 kt (39 mph, or tropical storm-force) winds. The location of the tropical storm-force winds are critical because, as will be seen in the Decision Making section, they help define when certain preparedness actions must be taken or completed.
A diagram of the wind radii from the above example is illustrated by the figure to the right. The significance of this information depends on what direction the storm is moving, where you are in relation to it, and how symmetrical the storm is. In this example, you can see that the wind fields are not very symmetrical (because the storm had travelled over Cuba's land surface for some time). If the hurricane were heading north, locations northeast of the center would experience stronger winds than those to the northwest (unless the storm changed direction or the wind field enlarged). If the storm were moving west, tropical storm-force winds would reach areas on the northwest side of the storm sooner than locations on the southwest side. The rest of the forecast blocks give the same information, valid at various times in the future up to 72 hours. Note that, as the forecast period gets farther out in time (the OUTLOOK sections-48 and 72 hours), the only information given is the radii of the 50 kt winds. This is because the longer-range forecasts are less accurate and more detailed information would not be very helpful. Something to Think About: Why Are Wind Radii Given in the NE, SE, SW, and NW Directions?