Gale Warning
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SBYC BurgeeSandy Bay Yacht Club
Weather Center


 

 

Wind Scales

Beaufort Wind Scale

Beaufort Number
or Force

Wind Speed

Description Effects Land / Sea
mph km/hr knots
0 <1 <1 <1 Calm Still, calm air, smoke will rise vertically.

Water is mirror-like.

1 1-3
mph
1-5
kph
1-3
knots
Light Air Rising smoke drifts, wind vane is inactive.

Small ripples appear on water surface.

2 4-7
mph
6-11
kph
4-6
knots
Light Breeze Leaves rustle, can feel wind on your face, wind vanes begin to move.

Small wavelets develop, crests are glassy.

3 8-12
mph
12-19
kph
7-10
knots
Gentle Breeze Leaves and small twigs move, light weight flags extend.

Large wavelets, crests start to break, some whitecaps.

4 13-18
mph
20-28
kph
11-16
knots
Moderate Breeze Small branches move, raises dust, leaves and paper.

Small waves develop, becoming longer, whitecaps.

5 19-24
mph
29-38
kph
17-21
knots
Fresh Breeze Small trees sway.

White crested wavelets (whitecaps) form, some spray.

6 25-31
mph
39-49
kph
22-27
knots
Strong Breeze Large tree branches move,  telephone wires begin to "whistle", umbrellas are difficult to keep under control.

Larger waves form, whitecaps prevalent, spray.

7 32-38
mph
50-61
kph
28-33
knots
Moderate or Near Gale Large trees sway, becoming difficult to walk.

Larger waves develop, white foam from breaking waves begins to be blown.

8 39-46
mph
62-74
kph
34-40
knots
Gale or Fresh Gale Twigs and small branches are broken from trees, walking is difficult.

Moderately large waves with blown foam.

9 47-54
mph
75-88
kph
41-47
knots
Strong Gale Slight damage occurs to buildings, shingles are blown off of roofs.

High waves (6 meters), rolling seas, dense foam, Blowing spray reduces visibility.

10 55-63
mph
89-102
kph
48-55
knots
Whole Gale or Storm Trees are broken or uprooted, building damage is considerable.

Large waves (6-9 meters), overhanging crests, sea becomes white with foam, heavy rolling, reduced visibility.

11 64-72
mph
103-117
kph
56-63
knots
Violent Storm Extensive widespread damage.

Large waves (9-14 meters), white foam, visibility further reduced.

12 73+
mph
118+
kph
64+
knots
Hurricane Extreme destruction, devastation.

Large waves over 14 meters, air filled with foam, sea white with foam and driving spray, little visibility.

 

Saffir-Simpson 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.

 

Wind Warnings

Category

Day Flags

Night Lights Description
Small Craft Advisory warn.gif
Red over white lights
Forecast winds of 18 to 33 knots (21 to 38 mph).
Small Craft Advisories may also be issued for hazardous sea conditions or lower wind speeds that may affect small craft operations.
Gale Warning warn.gif
warn.gif

White over red lights
Forecast winds of 34 to 47 knots (39 to 54 mph)
Storm Warning storm.gif
Red over red lights
Forecast winds of 48 knots (55 mph) or greater
Tropical Storm Warning storm.gif
Red over red lights
Forecast winds of 48 to 63 knots (55 to 73 mph) associated with a tropical storm
Hurricane Warning storm.gif
storm.gif

Red over white over red
Forecast winds of 64 knots (74 mph) or higher associated with a hurricane

 

Wind Barbs

Wind barbs point in the direction "from" which the wind is blowing.

Each short barb represents 5 knots, each long barb 10 knots. A long barb and a short barb is 15 knots, simply by adding the value of each barb together (10 knots + 5 knots = 15 knots). If only a station circle is plotted, the winds are calm.

 

1 knot = 1 nautical mile per hour = 6076 feet per hour = 1.15078 mph
1 mph = 1 mile per hour = 5280 feet per hour = 0.86898 knots per hour

Convert from one speed to another

Type a value in one box and click here to see the results

Kilometers per hour
Miles per hour
Knots

 



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