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Sponsors

FLIR Systems, Inc.
9 Townsend
West Nashua, NH 03063
Tom Milanette
603-324-7967
tom.milanette@flir.com

Mooringinfo
4 Boxwood Lane
Duxbury, MA  02332
781-248-6007
jvigilante@mooringinfo.com

New England Marine & Industrial, Inc.
200 Spaulding Turnpike
Portsmouth, NH 03801
Shannon McNally
603-436-2836
Shannon@newenglandmarine.com

Online Mooring
2485 Main St.
Rocky Hill, CT  06067
bhurley@onlinemooring.com

Rose's Marine/Rose's Oil Service
P.O. Box 1345
375 Main Street
Gloucester, MA 01930
Marty Bolcome
978-283-3334
marty@rosesoil.net

 


 


 


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.

The effects described in the Saffir-Simpson scale are from the National Hurricane Center

 

Dvorak Current Intensity Chart

The Dvorak technique is a method using enhanced Infrared and/or visible satellite imagery to quantitatively estimate the intensity of a tropical system.

CI -- Current Intensity
MWS -- Mean Wind Speed
MSLP -- Mean Sea Level Atmospheric Pressure in Millibars

CI Number MWS (Knots) MSLP (Atlantic) MSLP (Pacific) Saffir-Simpson Category (Approximate)
1 25 Knots      
1.5 25 Knots      
2 30 Knots 1009 mb 1000 mb  
2.5 35 Knots 1005 mb 997 mb  
3 45 Knots 1000 mb 991 mb  
3.5 55 Knots 994 mb 984 mb  
4 65 Knots 987 mb 976 mb 1 (64-83 KTS)
4.5 77 Knots 979 mb 966 mb 1 (64-83 KTS);
2 (84-96 KTS)
5 90 Knots 970 mb 954 mb 2 (84-96 KTS);
3 (97-113 KTS)
5.5 102 Knots 960 mb 941 mb 3 (97-113 KTS)
6 115 Knots 948 mb 927 mb 4 (114-135 KTS)
6.5 127 Knots 935 mb 914 mb 4 (114-135 KTS)
7 140 Knots 921 mb 898 mb 5 (136+ KTS)
7.5 155 Knots 906 mb 879 mb 5 (136+ KTS)
8 170 Knots 890 mb 858 mb 5 (136+ KTS)

 

 


Massachusetts Harbormasters Association, Inc.
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