Often Misunderstood Weather Terms

CLOUD COVER
Fine: Little cloud and no rainfall throughout the period. (Average cloud cover less than 2 oktas.)
Sunny: Bright sunshine most of the time with very little or no rainfall. (Average cloud cover less than 2 oktas, rainfall less than or equal a Trace)
Fair: Few low or medium clouds for most of the time and little or no rainfall. (Average cloud cover less than or equal 3 oktas, Rainfall less than or equal 0.01 inch or 0.254 mm.)
Mainly/Mostly Fair: More often fair than cloudy (including “fair with cloudy periods”), with no rainfall or only brief light showers. (Average cloud cover less than 5 oktas, rainfall less than or equal 0.02 inch or 0.508 mm)
Mainly/Mostly Sunny: More often sunny than fair (including “sunny with fair periods”) with little or no rainfall. (Average cloud cover less than 3 oktas, rainfall less than or equal 0.01 inch or 0.254 mm)
Mainly/Mostly Cloudy: Cloudy with fair breaks./td>
Partly Cloudy: No rainfall or only brief light showers. Total low and medium clouds less than or equal 3 oktas, high clouds more than 5 oktas, i.e. total clouds ranging from 3 to 6 oktas: rainfall less than or equal 0.03 inch or 0.762 mm.
Increasing/Decreasing Cloudiness: Amount of clouds generally increasing/decreasing to/from cloudy or overcast with only light showers or rainfall less than 0.05 inch or 1.27 mm.
Cloudy: Cloudy for most of the time. Generally lots of low or medium clouds. Average cloud cover equal 6 oktas, rainfall less than 0.05 inch or 1.27 mm
Cloudy To Overcast: Cloudy most of the time, otherwise overcast, with only light showers or rainfall. Average cloud cover equal 7 oktas, rainfall less than or equal 0.05 inch or 1.27 mm.
Considerable Cloudiness/Overcast: Overcast most of the time, otherwise cloudy. Average cloud cover greater than or equal 7 oktas, rainfall less than or equal 0.05 inch or 1.27mm
RAINFALL
Showers: Convective precipitation (not continuous) lasting from several minutes to one or two hours, with intensity from light-to-moderate to moderate-heavy
Drizzle: Precipitation from stratus clouds consisting of tiny droplets.
Brief Showers: Each shower lasting less than twenty minutes
Squalls: Light-to-moderate or moderate showers, each lasting less than half-an-hour preceded or accompanied by gusty winds
Squally Showers: Heavy showers or very heavy showers with thunderstorms and probably also lightning (used mainly during the day time)
Heavy Squalls: Moderate to heavy showers accompanied or proceeded by strong gusts
Heavy Showers: Convective precipitation lasting from half an hour to three hours with period(s) of heavy intensity
Very Heavy Showers: Convective precipitation lasting from half an hour to three hours with periods of very heavy or intense downpour
Thunderstorms: Moderate to heavy or heavy showers accompanied by thunder and/or lightning
Heavy Thunderstorms: Heavy or very heavy, or intense rainfall accompanied by thunder and lightning and possibly preceded or accompanied by gusty winds
Very Heavy Thunderstorms: Violent rainfall accompanied by gusty winds, thunder and lightning, likely causing some damage
Light Rainfall: Very light or light-to-moderate showers/rain over most areas
Intermittent Rainfall: Intermittent or continuous rainfall (from stratified clouds) intensity light-to-moderate to moderate-to- heavy unless otherwise indicated (by light, heavy or, exceptionally very heavy)
SPATIAL COVERAGE
Isolated: Occurring less than 10% – of the area
Widely Scattered: Occurring over 10% – 30% of the area
Scattered: Occurring over 30% – 60% of the area
Widespread: Many showers affecting most places. Occurring over 40% to 90% of the area
Many/Several Places: Occurring over 60% – 80% of the area
Most Places: Occurring over 80% – 95% of the area
??? Occurring over 85% – 100% of the area. e.g. cloudy with occasional showers
Eastern Areas: Surrey plus St Mary
Western Areas: Cornwall except Trelawny
Central Areas: Middlesex plus Trelawny but except St Mary
Northeastern Areas: Portland and St Mary
Southeastern Areas: St Thomas and St Andrew
Northwestern Areas: Hanover and St James
Southwestern Areas: Westmoreland and St Elizabeth
Northcentral Areas: St Ann and Trelawny
Southcentral Areas: St Catherine, Clarendon and Manchester
Inland Areas: Areas more than 3-miles away from the coast
Hilly Areas: All areas between 500 to 1500 ft
Hilly Ground: All areas above 1500 ft
Mountain Areas: Above 2000 ft
Foothills: All areas between 5 and 15 ft (rarely used)
Coastal Areas: Within 2 to 3 miles of seacoast
Coastal Plains: Below 500 ft and within 2 to 3 miles of seacoast
Plains/Low-lying Areas: Below 500 ft
PROBABILITIES
No term used: Over 85% average probability of occurrence
Likely: 50 to 85 % probability of occurrence
Chance Of: 15 to 50% average probability of occurrence of event which is unwanted by many users
Slight Chance Of: 5 to 15 % average probability of occurrence of an event which is unwanted by many users of the forecast (rarely used)
Risk: Same as chance but used only with unwanted events (e.g. “risk of very heavy thunderstorm”
Slight Risk: 5 to 15 % average probability of occurrence of unwanted event
Percentage Probability: This is reserved for the probability of occurrence at any one point and the term is therefore used in point forecasts but not used in the island forecast (e.g. 60% probability of showers)
TIME
Dawn: Morning/ evening twilight 5-7 a.m. / p.m. EST.
Morning: 6:00 a.m. to 12 noon
Early Morning: 6:00 to 8:00 a.m.
Mid Morning: 8:00 to 10:00 a.m.
Forenoon: 10:00am to noon
Afternoon: Noon to 6:00p.m.
Early Afternoon: Noon to 3:00p.m.
Mid Afternoon: 2:00p.m. to 4:00p.m.
Late Afternoon: 3:00p.m. to 6:00p.m.
Evening: 6:00p.m. to midnight
Night: 7:00pm to 5:00a.m.
Brief: Less than 20 minutes
Prolonged: More than 2 hours
Occasional: Occurring at least 3 times