TROPICAL DEPRESSION: A storm system displaying a noticeable rotary circulation with maximum sustained wind speeds of 38 miles per hour (33 knots).
TROPICAL STORM: Displays a substantial rotary circulation with sustained winds of 39 to 73 miles per hour (34-63 knots). When reaching tropical storm strength, a storm is given a name to aid in tracking.
HURRICANE: Strong rotary circulation with sustained surface winds of 74 miles per hour (64 knots) or more. In the western North Pacific and most of the South Pacific, such storms are called Typhoons. In the Indian Ocean they are called Cyclones.
GALE WARNING: Coastal wind speeds between 39 and 54 miles per hour (34-47 knots).
STORM WARNING: May be issued when winds of 55-73 miles per hour (48-63 knots) are expected on area waters.
HURRICANE WATCH: Issued when there is a threat of hurricane conditions developing within 24 to 36 hours.
HURRICANE WARNING: Hurricane conditions with winds of 74 miles per hour or more (64 knots) and/or dangerously high tides and waves are expected within 24 hours. People within the warning area should begin to take action to protect life and property.
TORNADO/SEVERE THUNDERSTORM WATCH: Tornadoes and severe thunderstorms often develop when hurricanes and tropical storms make landfall. A watch means these storms are possible.
TORNADO/SEVERE THUNDERSTORM WARNING: Tornadoes or severe thunderstorms are occurring within the warning area.
Category 1/ 28.94"/ 74-95 MPH /4-5 ft - MINIMAL
Primarily to trees, foliage, and unanchored mobile homes. No real damage to other structures. Some small craft my be torn from moorings.
Category 2/28.50"/96-110 MPH/6-8 ft - MODERATE
Some trees blown down. Some window, door and roofing damage. Small craft torn from moorings in unprotected anchorages. Some evacuation of shoreline residences and low-lying islands.
Category 3 /27.91"/ 111-130 MPH/ 9-12 ft - EXTENSIVE
Large trees blown down. Some structural damage to small buildings. Mobile homes destroyed. Serious coastal flooding. Many small structures near coast destroyed by wind and waves. Almost all small boats torn from moorings.
Category 4/ 27.17"/ 131-155 MPH/ 13-18 ft - EXTREME
Extensive damage to roofs on many small residences. Terrain 10 feet or less above sea level flooded. Escape routes cut by rising water 3 to 5 hours before center arrives. Massive coastal evacuation required.
Category 5/ 27.16"/ 156+ MPH/ More than 18 ft - CATASTROPHIC
Complete failure of roofs on residences and many commercial structures. Small buildings overturned or blown away. Massive evacuation from low ground within 5-10 miles of the coast.
A hurricane tracking chart appears in the January issue Field Forum, and is suitable for reproduction. Larger (and more sophisticated) charts are available from commercial sources.
For example, Kornor Enterprises sells heavy-duty plastic laminated charts in various sizes. Erasable marker and instructions are included. The company has agreed to sell the charts to ARRL members at a special, reduced price: 17x22"-$12.50; 11x15" -- $10.50; and 8.5x11" -- $8.50. (Includes shipping/handling). Identify yourself as an ARRL member when ordering. Order from Kornor Enterprises, PO Box 461, Cleveland, OH 44094, American Express, VISA, and MasterCard credit cards accepted. The KORNOR map is used by the staff at the National Hurricane Center in Coral Gables, Florida.
On the KORNOR map, solid black lines are drawn for every five (5) degrees of latitude and longitude. White lines are drawn for every (1) degree. By definition, one degree of latitude is equal to 60 nautical miles. This gives us a convenient way of estimating distances on a chart. Measure the distance between any two points, then lay this distance out on one of the north south longitude lines. Count the number of degrees of latitude and
multiply by 60 to find the distance in nautical miles. To convert to statute miles, multiply that answer by 1.15. One nautical mile equals 1.15 statute miles. One knot (nautical mile per hour) equals 1.15 statute miles per hour.
Hurricane tracking software is also available.