MONSOON

Changing winds

Characteristics of Monsoon
 

The northeast monsoon is the major rainy season in the country. Monsoon weather systems which develop in conjunction with cold air outbreaks from Siberia produce heavy rains which often cause severe floods along the east coast states of Kelantan, Trengganu, Pahang and East Johore in Peninsular Malaysia, and in the state of Sarawak in East Malaysia.

* Monsoon floods

Following the southward march of the monsoons, typical expected monthly rainfall maximum are:

Kelantan, Trengganu

600 mm (November)

Pahang and East Johore

600 mm (December)

Sarawak

400-700 mm (January)

The southwest monsoon is comparatively drier throughout the country except for the state of Sabah in East Malaysia. During this season, most states experience monthly rainfall minimum (typically 100 - 150 mm). This is attributed to relatively stable atmospheric conditions in the equatorial region. In particular, the dry condition in Peninsular Malaysia is accentuated by the rain shadow effect of the Sumatran mountain range. Sabah is relatively wetter (exceeding 200 mm) due to the tail effect of typhoons which frequently traverse the Philippine islands in their journey across the South China Sea and beyond.

During the intermonsoon periods, winds are light and variable. Morning skies are often clear and this favours thunderstorm development in the afternoon. In the west coast states of Peninsular Malaysia, thunderstorms contribute to a mean monthly rainfall maximum in each of the two transition periods.

Weather Advisories and Warnings

The Malaysian Meteorological Service monitors closely the changing weather situation and issues weather statements, outlooks, advisories and warnings when the need arises. The different categories of monsoon advisories and warnings are :

 

Heavy Rainfall Advisories

issued when there is a possibility of heavy rainfall occurrence within 24 to 48 hours.

Heavy Rainfall Warnings

issued when latest information received indicate that heavy rainfall is expected.

Strong Wind and Rough Seas Advisories

issued when there is a possibility of strong wind and rough seas within the Malaysian waters within 24 to 48 hours.

Strong Wind and Rough Seas Warnings

issued when latest information received indicate that strong wind and rough seas are expected.

These severe weather advisories and warnings are published in the newspapers and broadcasted over radio and television.