| Bft |
MPH |
Knots |
Name |
Sea Description |
|
3
|
8-12 |
6.21-10.53 |
Gentle |
Large wavelets; crests begin to break, Breeze
scattered whitecaps |
|
4
|
13-18 |
10.53-15.39 |
Moderate |
Small waves 0.5 - 1.25 meters high, Breeze becoming
longer; numerous whitecaps |
|
5
|
19-24 |
15.39-20.79 |
Fresh |
Moderate waves of 1.25 - 2.5 m. Breeze taking
longer form; many whitecaps; some spray |
|
6
|
25-31 |
20.79-26.73 |
Strong |
Larger waves 2.5 - 4 meters forming; Breeze whitecaps
everywhere, more spray |
|
7
|
32-38 |
26.73-33.21 |
Near gale |
Sea heaps up, waves 4 - 6 m; Gale white foam
from breaking waves begins to be blown in streaks |
|
8
|
39-46 |
33.21-40.23 |
Gale |
Moderately high (4 - 6 m) waves of greater length;
edges of crests begin to break into spindrift; foam is blown in well-marked
streaks |
|
9
|
47-54 |
40.23-47.79 |
Strong gale |
High waves (6 m); sea begins Gale to roll; dense
streaks of foam; spray may reduce visibility |
| 10 |
55-63 |
47.79-55.35 |
Storm |
Very high waves (6 - 9 m) with overhanging crests;
sea takes a white appearance as foam is blown in very dense streaks; rolling
is heavy and visibility is reduced |
| 11 |
64-72 |
55.35-63.44 |
Violent storm |
Exceptionally high (9-14 m) waves; Storm sea
covered with white foam patches; visibility still more reduced |