Beaufort scale used in Taiwan and mainland China, which are often affected by typhoons. Internationally, WMO Manual on Marine Meteorological Services (2012 edition) defined the Beaufort Scale only up to force 12 and there was no recommendation on the use of the extended scale. Wind speed on the 1946 Beaufort scale is based on the empirical relationship: Where "v" is the equivalent wind speed at 10 metres above the sea surface and "B" is Beaufort scale number. For example, "B" = 9.5 is related to 24.5 m/s which is equal to the lower limit of "10 Beaufort". Using this formula the highest
Great Lakes Storm of 1913 indicating a storm warning with northwesterly winds. By late afternoon, the storm signal flags were replaced with a vertical sequence of red, white, and red lanterns, indicating that a hurricane with winds over 74 mph (119 km/h) was coming. (The word "hurricane" here does not refer to a tropical cyclone, but to Force 12 winds on the Beaufort scale.) The winds on Lake Superior had already reached 50 mph (80 km/h), and an accompanying blizzard was moving toward Lake Huron. By Saturday, the storm's status had been upgraded to "severe". The storm was centered over eastern Lake Superior, covering the