This page provides help wind the many ways of
expressing Wind. Subjects covered
here:
Wind Speed Definitions
Marine Warnings
Beaufort Scale
Wind Speed Chart
Northeaster
Windspeed and Sea
Height
Direction: In reference to true North, to
eight points of the compass. Winds are described by the direction they come
from.
Speed:
Generally in miles per hour (mph), kilometers per hour (kmph), except
Marine products which are in knots.
Gusty: Rapid fluctuations of speed of 10 mph.
| 1 kmph | = | .62 mph | = | .54 knot | light | - | <10 mph | ||
| 1 mph | = | .87 knot | = | 1.62 kmph | breezy | - | 5 to25 mph | ||
| 1 knot | = | 1.15 mph | = | 1.86 km | windy | - | 20 to 30 mph | ||
| 1 mile | = | 5280 ft | very windy | - | 40 to 60 mph | ||||
| 1 nautical mile | = | 6076 ft | high winds | - | 40 to 60 mph | ||||
| damaging winds | - | 60 mph |
- Small Craft Advisory: Forecast winds of 18 to 33 knots; also issued for hazardous sea conditions.
- Gale Warning: Forecast winds of 34 to 47 knots.
- Storm Warning: Forecast winds of 48 knots or greater.
- Tropical Storm Warning: Forecast winds of 34 to 63 knots associated with a tropical storm.
- Hurricane Warning: Forecast winds of 64 knots or greater associated with a hurricane
Beaufort Scale: Wind Speed Chart:
|
Force |
Knots | Description | Km | Mile/Hour | Knots | |
|---|---|---|---|---|---|---|
| 0 | 0-1 | Mirror Calm | 10 | 6 | 5 | |
| 1 | 1-3 | Gentle Ripples | 15 | 9 | 8 | |
| 2 | 4-6 | Small Wavelets | 20 | 12 | 11 | |
| 3 | 7-10 | Large Wavelets | 25 | 15 | 14 | |
| 4 | 11-16 | Small Waves | 30 | 19 | 16 | |
| 5 | 17-21 | White Caps | 35 | 22 | 19 | |
| 6 | 22-27 | Large Waves/Spray | 40 | 25 | 22 | |
| 7 | 28-33 | Streaking Foam | 45 | 28 | 24 | |
| 8 | 34-40 | Gale/Spindrift | 50 | 31 | 27 | |
| 9 | 41-47 | Severe Gale | 55 | 34 | 30 | |
| 10 | 48-55 | Storm/White Seas | 60 | 37 | 33 | |
| 11 | 56-63 | Violent Storm | 65 | 40 | 35 | |
| 12 | 64+ | Hurricane | 70 | 43 | 38 | |
| 80 | 50 | 43 | ||||
| 90 | 56 | 49 | ||||
| 100 | 62 | 54 |
Note: Speeds have been rounded off to nearest full number
Northeaster: Here's my layman's try at a Northeaster definition. A Northeaster is counter-clock wise turning cyclone (a storm system circulating around a center) as opposed to a hurricane which turns right in the northern hemisphere. Northeasters are spawned by a very curvy Jet Stream that dips very low and then follows the eastern coast north and finally turning east over and north of Canada. They typically form near the Bahamas or north of Cuba, along the Appalachians or off Cape Hatteras. The Jet Stream then drags them northeast ward. Some time a High further north blocks its path and so it churns over the ocean for a long time sending beach-eating waves onshore.
WIND SPEED/SEA HEIGHT RELATIONSHIPS
| Wind Speed | Sea Conditions |
|---|---|
| 0-3 KTS | SEA LIKE MIRROR |
| 4-6 KTS | RIPPLES, LESS THAN 1 FT |
| 7-10 KTS | SMOOTH WAVELETS, 1-2 FT |
| 11-16 KTS | SMALL WAVES, 2-4 FT |
| 17-21 KTS | MODERATE WAVES, MANY WHITECAPS, 4-8 FT |
| 22-27 KTS | LARGE WAVES,SPRAY, 8-13 FT |
| 28-33 KTS | HEAPED SEAS, FOAM FROM BREAKING WAVES, 13-20 FT |
| 34-40 KTS | HIGH WAVES, FOAM BLOWN IN WELL MARKED STREAKS, 13-20 FT |
| 41-47 KTS | SEAS ROLL, SPRAY MAY REDUCE VISIBILITY, 13-20 FT |
| 48-55 KTS | VERY HIGH WAVES, WHITE SEAS, OVERHANGING CRESTS 20-30 FT |
| 56-63 KTS | EXCEPTIONALLY HIGH WAVES, 30-45 FT |
| OVER 63 KTS | AIR FILLED WITH FOAM, SEA COMPLETELY WHITE, OVER 45 FT |
THIS CHART IS BASED ON CRITERIA USED BY THE WORLD METEOROLOGICAL ORGANIZATION. MARINERS SHOULD REALIZE THAT THESE VALUES ARE REACHED AFTER WINDS HAVE BLOWN STEADILY OVER A LARGE AREA FOR AN EXTENDED PERIOD OF TIME. ALSO, THE VALUES GIVEN ARE AVERAGE OBSERVED WAVE HEIGHTS, NOT THE HIGHEST THAT MAY BE SEEN FOR A GIVEN WIND SPEED.
Life's a Reach, Then you Jibe!
Revised:
January 14, 2004