A quick summary of meteorological terms that RYA Advanced Powerboat and Yachtmaster (Coastal and Offshore) exam candidates should refresh before their practical exam. Some of the these “met. terms” are covered at RYA Day Skipper Shorebased. Some are covered at RYA Yachtmaster Offshore Shorebased.
VISIBILITY DEFINITIONS
| TERM | DEFINITION |
|---|---|
| Very Poor (Fog) * | Visibility less than 1,000 metres |
| Poor * | Visibility between 1,000 metres and 2 nautical miles |
| Moderate * | Visibility between 2 and 5 nautical miles |
| Good * | Visibility more than 5 nautical miles |
Example: “Visibility- Moderate”
TIMING IN MARINE WEATHER FORECASTS
| TERM | DEFINITION |
|---|---|
| Imminent * | Expected within six hours of time of issue |
| Soon * | Expected within six to 12 hours of time of issue |
| Later * | Expected more than 12 hours from time of issue |
Example: “Moderate Visibility, Later.”
WIND WARNINGS DEFINITIONS
| TERM | DEFINITION |
|---|---|
| Strong Wind * | Winds of force 6 |
| Gale * | Winds of force 8 |
| Severe Gale * | Winds of force 9 |
| Storm * | Winds of force 10 |
| Violent Storm * | Winds of force 11 |
| Hurricane Force * | Winds of force 12 |
Example: “A Strong wind warning is in force for sea areas, Dover, Wight, Portland and Plymouth”
WIND FORECASTING TERMS
| TERM | DEFINITION |
|---|---|
| Veering * | The changing of the wind direction clockwise, e.g. E to S |
| Backing * | The changing of the wind in the opposite direction to veering (anticlockwise), e.g. E to N |
| Becoming Cyclonic * | Indicates that there will be considerable change in wind direction across the path of a depression within the forecast area |
Example: “Southerly Gale force winds will veer, and increase South West Force 9 gusting 10”
SEA STATE TERMS / DEFINITIONS
| TERM | DEFINITION |
|---|---|
| Smooth * | Wave height less than 0.5 m |
| Slight * | Wave height of 0.5 to 1.25 m |
| Moderate * | Wave height of 1.25 to 2.5 m |
| Rough * | Wave height of 2.5 to 4.0 m |
| Very Rough * | Wave height of 4.0 to 6.0 m |
| High * | Wave height of 6.0 to 9.0 m |
| Very High * | Wave height of 9.0 to 14.0 m |
| Phenomenal * | Wave height more than 14.0 m |
Example: “SEA STATE- Moderate or rough West of Orkney, slight or moderate elsewhere.”
MOVEMENT OF PRESSURE SYSTEMS
| Slowly * | Moving at less than 15 knots |
|---|---|
| Steadily * | Moving at 15 to 25 knots |
| Rather Quickly * | Moving at 25 to 35 knots |
| Rapidly * | Moving at 35 to 45 knots |
| Vert Rapidly * | Moving at more than 45 knots |
PRESSURE TENDENCY DEFINITIONS
| Rising (or falling) more slowly * | Pressure rising (or falling) at a progressively slower rate through the preceding three hours |
|---|---|
| Rising (or falling) slowly * | Pressure change of 0.1 to 1.5 hPa in the preceding three hours |
| Rising (or falling) * | Pressure change of 1.6 to 3.5 hPa in the preceding three hours |
| Rising (or falling) quickly * | Pressure change of 3.6 to 6.0 hPa in the preceding three hours |
| Rising (or falling) very rapidly * | Pressure change of more than 6.0 hPa in the preceding three hours |
| Now Rising (or falling) * | Pressure has been falling (rising) or steady in the preceding three hours, but at the time of observation was definitely rising (falling) |
Note: 1 hPa = 1 mb
DOUG’S COMMENT FOR EXAM CANDIDATES
The observant reader will have noticed that each term has a coloured dot next to it. Either * or *.
I would suggest that Advanced Powerboat and Yachtmaster Coastal, Exam candidates should as a minimum know all of the definitions marked with a *, however strong candidates might also know some of those married with a *. (If however your examiner feels differently then don’t blame me!)
I suggest that a strong Yachtmaster Offshore candidate would know all of the * terms and the vast majority, if not all of the * terms.