INTRODUCTION Singapore has one of the highest rate of lightning activity in the world. Lying near the Equator, the weather is hot and humid almost all year round. Conditions are favourable for the development of lightning producing thunderstorm clouds. An average of 171 thunderstorm days (days when thunder is heard) are recorded annually in Singapore.
The monthly distribution of the number of thunder days (see figure 1) shows a peak in April/May and November, with an average of 20 thunder days and a low of 4 to 6 days in the months of January and February respectively. The preferred time of the day for thunderstorm to occur (see figure 2) is between 2 pm and 6 pm in the afternoon for all months of the year as diurnal heating and convection play an important role in thunderstorm development here.
Fig 1. AVERAGE NO. OF THUNDER DAYS, CHANGI AIRPORT
Fig 2. NO. OF HOURLY THUNDERSTORM OCCURRENCES
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HAZARDS OF LIGHTNING While most lightning strike the ground harmlessly, their destructive power can be tremendous. Lightning can ignite forest fires, damage electronic equipment, disrupt electrical power and telecommunication systems. Lightning also cause damage to trees in parks and gardens. There are 2 major causes of injuries and deaths from lightning. One is being struck directly and the other is a phenomenon known as 'side flash'. A side flash can occur when a person standing near a tree or metal pipe, frame or unprotected shelter (particularly those with metal roofing) touches these objects or are close to them when a lightning discharge occur. The person becomes a convenient conductor for the electric current to the ground and hence is injured or killed. In Singapore, records on lightning fatalities show an average of 0.35 deaths per million population (year 2000-2003) as compared to 0.6 in the United States, 0.2 in the United Kingdom and 1.5 in South Africa. Also deaths from lightning are higher in April and November. The victims were often in open areas such as sea, beaches and football fields. Also most deaths in sheltered areas occurred while the victims were under a hut, a shed or trees.
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MONITORING AND TRACKING THUNDERSTORMS/LIGHTNING Besides visual observations and the use of weather radar, the Meteorological Services Division monitors the development and movements of lightning activities within 250 kilometre range of Singapore with an advanced lightning detection and tracking system.
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PROVISION OF LIGHTNING ACTIVITY INFORMATION Thunderstorms and the associated lightning activities, unlike large scale weather systems such as typhoons and hurricanes, are relatively short-lived severe weather phenomena. Each individual thunderstorm cloud normally has a life-span of 1 to 1.5 hours and covers a horizontal distance of a few kilometres. Larger storms which last longer are usually made up of a congregation of several smaller individual thunderstorm cells. A thunderstorm usually moves and changes its shape as it grows and decays. New cells usually form near existing storms. Information on the expectation of lightning activity is provided by the Meteorological Services Division through its 12-hr local weather forecasts. Besides being broadcast by radio stations, the forecast can be obtained from the telephone Weather Information Dissemination System (WIDS). Also lightning risk watch is provided to specific users on a subscription basis. | 
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SOME LIGHTNING DOs AND DON'Ts
DOs
TAKE SHELTER IN A HOUSE, LARGE BUILDING OR CAR
IN OPEN AREAS, SEEK SHELTER IN A LOW AREA SUCH AS RAVINE
IN A FOREST, SEEK SHELTER IN A LOW AREA SUCH AS UNDER A THICK GROWTH OF SMALL TREES
IN OPEN WATER, HEAD FOR THE SHORE
ON A BICYCLE.MOTORBIKE OR GOLF CART, GET OFF
ON A GOLF COURSE (WITHOUT ANY NEARBY SHELTERS), PUT DOWN YOUR CLUBS, TAKE OFF SPIKE SHOES AND CROUCH INTO A BALL ON THE GROUND
IN A GROUP IN THE OPEN, SPREAD OUT
DON'Ts
AVOID USING THE TELEPHONE, ELECTRIC APPLIANCES AND ELECTRONIC EQUIPMENT
DO NOT STAND UNDER TALL TREES OR NEXT TO A TELEPHONE POLE
DO NOT STAY IN THE OPEN OR ON HIGH GROUND SUCH AS ROOF TOPS, HILL TOPS ETC...
STAY CLEAR OF WIRE OR METAL FENCES, METAL PIPES AND RAILS
DO NOT HOLD METAL OBJECTS SUCH AS UMBRELLAS, GOLF CLUBS OR BICYCLES
DO NOT LOAD AND UNLOAD EXPLOSIVE OR INFLAMMABLE MATERIALS
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