Weather glossary
The terms we use in forecasts and warnings.
Warnings and products
| Term | Meaning |
|---|---|
| Advisory | Conditions that are hazardous for some users or activities, below warning level |
| Watch | Hazardous conditions are likely; prepare |
| Warning | Hazardous conditions are expected or occurring; act now |
| CAP | Common Alerting Protocol — the structured format warnings are published in |
| METAR | Routine hourly observation of conditions at an aerodrome |
| TAF | Terminal Aerodrome Forecast — forecast conditions at an aerodrome |
| Synopsis | The forecaster's summary of the overall weather pattern |
Tropical systems
| Term | Meaning |
|---|---|
| Tropical wave | A trough moving west across the Atlantic; the most common cause of showery spells in Grenada |
| Tropical depression | A closed circulation with winds up to 33 kt |
| Tropical storm | Winds of 34 to 63 kt; the system is named at this stage |
| Hurricane | Winds of 64 kt or more |
| Major hurricane | Category 3 or above — winds of 96 kt or more |
| Storm surge | Sea water pushed onshore by a storm's wind and low pressure |
| Eye | The calm centre of a hurricane; the wind returns from the opposite direction after it passes |
Rain, wind and sea
| Term | Meaning |
|---|---|
| Isolated | Affecting less than about a quarter of the area |
| Scattered | Affecting roughly a quarter to a half of the area |
| Widespread | Affecting most of the area |
| Knot (kt) | One nautical mile per hour — about 1.85 km/h |
| Significant wave height | The average height of the highest third of waves |
| Swell | Waves generated by distant weather, arriving with a long period |
| Trade winds | The steady east-north-easterly flow that dominates Grenada's weather |
| Saharan dust | Mineral dust carried across the Atlantic, hazing the sky and raising particulate levels |