TROPICAL WAVE: A trough or cyclonic curvature maximum in the trade-wind easterlies. The wave may reach maximum amplitude in the lower middle troposphere.

TROUGH: An elongated area of relatively low atmospheric pressure, usually not associated with a closed circulation, and thus used to distinguish from a closed low. The opposite of ridge.

WARM ADVECTION: Transport of warm air into an area by horizontal winds.

WIND SHEAR: Variation in wind speed (speed shear) and/or direction (directional shear) over a short distance. Shear usually refers to vertical wind shear, i.e., the change in wind with height,

Clouds And Rainfall Definitions.

BRIEF SHOWERS: Occurring for less than 20 minutes.

CLOUDY: Cloudy most of the time, with relatively high probability of rainfall.

COASTAL AREAS: Less than 5 miles (8km) from the sea and below 500ft.

FAIR AND SUNNY: Little clouds for most of the time with relatively low probability of rainfall.

FINE: Few clouds, no rain expected.

INLAND AREAS: More than five miles (8km) from the sea.

ISOLATED SHOWERS: Occurring over less than 10% of the area.

HILLY AREAS: All areas above 500ft.

LOW LYING AREAS: Areas below 500ft.

MOST PLACES: Occurring over 80%__95% of the area.

OCCASIONAL: Occurring at least three times.

OVERCAST: Cloudy all the time, with relatively high probability of rainfall.

PARTLY CLOUDY: Varying at times between fair and mainly cloudy with relatively low probability of rainfall.

PROLONG: Occurring for more than 2 hours.

RAIN: Continuous rainfall from mainly stratified cloud (sheet clouds), with intensity from light to moderate or moderate to heavy

SCATTERED SHOWERS: Occurring over 30%__60% of the area.

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