Beaufort Wind Scale
The Beaufort Scale reflects both wind strength and sea conditions. Developed in 1805 by Admiral Sir Francis Beaufort of the British Navy. The scale divides wind and sea conditions into 12 “Forces” ranging from calm to hurricane. It describes typical conditions offshore in large bodies of water.
| Beaufort Number or Force | Wind Speed and Description | Effects Land/Sea | Probable Wave Height | ||
|---|---|---|---|---|---|
| MPH | Knots | Description | |||
| 0 | <1 | <1 | Calm | Still, calm air, smoke will rise vertically. Smooth like a mirror. | 0 |
| 1 | 1-3 | 1-3 | Light Air | Rising smoke drifts, wind vane is inactive. Small ripples like fish scales. | ¼ – ½ foot |
| 2 | 4-7 | 4-6 | Light Breeze | Leaves rustle, can feel wind on your face, wind vanes begin to move. Short, small pronounced wavelets with no crests. | ¼ – ½ foot |
| 3 | 8-12 | 7-10 | Gentle Breeze | Leaves and small twigs move, light weight flags extend. Large wavelets, crests start to break, some whitecaps. | 2 feet |
| 4 | 13-18 | 11-16 | Moderate Breeze | Small branches move, raises dust, leaves and paper. Small waves develop, becoming longer, whitecaps. | 4 feet |
| 5 | 19-24 | 17-21 | Fresh Breeze | Small trees sway. Moderate lengthening waves, with many white caps and some spray. | 6 feet |
| 6 | 25-31 | 22-27 | Strong Breeze | Large tree branches move, telephone wires begin to “whistle”Large waves, extensive white caps, some spray. | 10 feet |
| 7 | 32-38 | 28-33 | Near Gale | Large trees sway, becoming difficult to walk. Heaps of waves, with some breakers whose foam is blown downwind in streaks. | 14 feet |
| 8 | 39-46 | 34-40 | Gale | Twigs and small branches are broken from trees, walking is difficult. Moderately large waves with blown foam. | 18 feet |
| 9 | 47-54 | 41-47 | Strong Gale | Slight damage occurs to buildings, shingles are blown off of roofs. Rolling seas, dense foam, Blowing spray reduces visibility. | 23 feet |
| 10 | 55-63 | 48-55 | Whole Gale or Storm | Trees are broken or uprooted, building damage is considerable. Very high waves with long, overhanging crests. The sea looks white, visibility is greatly reduced. | 29 feet |
| 11 | 64-72 | 56-63 | Violent Storm | Extensive widespread damage. Wave edges are blown into froth, and the sea is covered with patches of foam. | 37 feet |
| 12 | 73+ | 64+ | Hurricane | Extreme destruction, devastation. The air is filled with foam and spray, and the sea is completely white, little visibility. | 45 feet |
Hurricane Scale
| Category | Wind Strength/Pressure | Effects |
|---|---|---|
| 1 | 65 to 83 knots 74 to 95 mph 119 to 153 kph 980 mb |
Storm surge generally 4-5 ft above normal. No real damage to building structures. Damage primarily to unanchored mobile homes, shrubbery, and trees. Some damage to poorly constructed signs. Also, some coastal road flooding and minor pier damage. Hurricanes Allison of 1995 and Danny of 1997 were Category One hurricanes at peak intensity. |
| 2 | 84 to 95 knots 96 to 110 mph 154 to 177 kph 980 – 965 mb |
Storm surge generally 6-8 feet above normal. Some roofing material, door, and window damage of buildings. Considerable damage to shrubbery and trees with some trees blown down. Considerable damage to mobile homes, poorly constructed signs, and piers. Coastal and low-lying escape routes flood 2-4 hours before arrival of the hurricane center. Small craft in unprotected anchorages break moorings. Hurricane Bertha of 1996 was a Category Two hurricane when it hit the North Carolina coast, while Hurricane Marilyn of 1995 was a Category Two Hurricane when it passed through the Virgin Islands. |
| 3 | 96 to 113 knots 111 to 130 mph 178 to 209 kph 964 – 945 mb |
Storm surge generally 9-12 ft above normal. Some structural damage to small residences and utility buildings with a minor amount of curtainwall failures. Damage to shrubbery and trees with foliage blown off trees and large tress blown down. Mobile homes and poorly constructed signs are destroyed. Low-lying escape routes are cut by rising water 3-5 hours before arrival of the hurricane center. Flooding near the coast destroys smaller structures with larger structures damaged by battering of floating debris. Terrain continuously lower than 5 ft above mean sea level may be flooded inland 8 miles (13 km) or more. Evacuation of low-lying residences with several blocks of the shoreline may be required. Hurricanes Roxanne of 1995 and Fran of 1996 were Category Three hurricanes at landfall on the Yucatan Peninsula of Mexico and in North Carolina, respectively. |
| 4 | 114 to 134 knots 131 to 155 mph 210 to 249 kph 944- 920 mb |
Storm surge generally 13-18 ft above normal. More extensive curtainwall failures with some complete roof structure failures on small residences. Shrubs, trees, and all signs are blown down. Complete destruction of mobile homes. Extensive damage to doors and windows. Low-lying escape routes may be cut by rising water 3-5 hours before arrival of the hurricane center. Major damage to lower floors of structures near the shore. Terrain lower than 10 ft above sea level may be flooded requiring massive evacuation of residential areas as far inland as 6 miles (10 km). Hurricane Luis of 1995 was a Category Four hurricane while moving over the Leeward Islands. Hurricanes Felix and Opal of 1995 also reached Category Four status at peak intensity. |
| 5 | 135+ knots 155+ mph 249+ kph < 920 mb |
Storm surge generally greater than 18 ft above normal. Complete roof failure on many residences and industrial buildings. Some complete building failures with small utility buildings blown over or away. All shrubs, trees, and signs blown down. Complete destruction of mobile homes. Severe and extensive window and door damage. Low-lying escape routes are cut by rising water 3-5 hours before arrival of the hurricane center. Major damage to lower floors of all structures located less than 15 ft above sea level and within 500 yards of the shoreline. Massive evacuation of residential areas on low ground within 5-10 miles (8-16 km) of the shoreline may be required. There were no Category Five hurricanes in 1995, 1996, or 1997. Hurricane Gilbert of 1988 was a Category Five hurricane at peak intensity and is the strongest Atlantic tropical cyclone of record. |
Marine Radio Frequencies
| Channel Number | MHz | Use |
|---|---|---|
| 01A | 156.050 | Port Operations and Commercial. VTS in selected areas. |
| 05A | 156.250 | Port Operations. VTS in selected areas. |
| 06 | 156.300 | Intership Safety |
| 07A | 156.350 | Commercial |
| 08 | 156.400 | Commercial (Intership only) |
| 09 | 156.450 | Boater Calling. Commercial and Non-Commercial. |
| 10 | 156.500 | Commercial |
| 11 | 156.550 | Commercial. VTS in selected areas. |
| 12 | 156.600 | Port Operations. VTS in selected areas. |
| 13 | 156.650 | Intership Navigation Safety (Bridge-to-bridge). Ships >20m length maintain a listening watch on this channel in US waters. |
| 14 | 156.700 | Port Operations. VTS in selected areas. |
| 15 | 156.750 | Environmental (Receive only). Used by Class C EPIRBs. |
| 16 | 156.800 | International Distress, Safety and Calling. Ships required to carry radio, USCG, and most coast stations maintain a listening watch on this channel. |
| 17 | 156.850 | State Control |
| 18A | 156.900 | Commercial |
| 19A | 156.950 | Commercial |
| 20 | 161.600 | Port Operations (duplex) |
| 20A | 157.000 | Port Operations |
| 21A | 157.050 | U.S. Coast Guard only |
| 22A | 157.100 | Coast Guard Liaison and Maritime Safety Information Broadcasts. Broadcasts announced on channel 16. |
| 23A | 157.150 | U.S. Coast Guard only |
| 24 | 161.800 | Public Correspondence (Marine Operator) |
| 25 | 161.850 | Public Correspondence (Marine Operator) |
| 26 | 161.900 | Public Correspondence (Marine Operator) |
| 27 | 161.950 | Public Correspondence (Marine Operator) |
| 28 | 162.000 | Public Correspondence (Marine Operator) |
| 63A | 156.175 | Port Operations and Commercial. VTS in selected areas. |
| 65A | 156.275 | Port Operations |
| 66A | 156.325 | Port Operations |
| 67 | 156.375 | Commercial. Used for Bridge-to-bridge communications in lower Mississippi River. Intership only. |
| 68 | 156.425 | Non-Commercial |
| 69 | 156.475 | Non-Commercial |
| 70 | 156.525 | Digital Selective Calling (voice communications not allowed) |
| 71 | 156.575 | Non-Commercial |
| 72 | 156.625 | Non-Commercial (Intership only) |
| 73 | 156.675 | Port Operations |
| 74 | 156.725 | Port Operations |
| 77 | 156.875 | Port Operations (Intership only) |
| 78A | 156.925 | Non-Commercial |
| 79A | 156.975 | Commercial. Non-Commercial in Great Lakes only |
| 80A | 157.025 | Commercial. Non-Commercial in Great Lakes only |
| 81A | 157.075 | U.S. Government only – Environmental protection operations. |
| 82A | 157.125 | U.S. Government only |
| 83A | 157.175 | U.S. Coast Guard only |
| 84 | 161.825 | Public Correspondence (Marine Operator) |
| 85 | 161.875 | Public Correspondence (Marine Operator) |
| 86 | 161.925 | Public Correspondence (Marine Operator) |
| 87 | 161.975 | Public Correspondence (Marine Operator) |
| 88 | 162.025 | Public Correspondence only near Canadian border. |
| 88A | 157.425 | Commercial, Intership only. |
NOAA Weather Radio Frequencies (MHz)
| WX1 | — | 162.550 |
| WX2 | — | 162.400 |
| WX3 | — | 162.475 |
| WX4 | — | 162.425 |
| WX5 | — | 162.450 |
| WX6 | — | 162.500 |
| WX7 | — | 162.525 |