If I am not wrong, the category status applies to the lightning
risk in that particular sector in question. Singapore is divided
into many sectors, and each sector can have a particular status at
any time, the most common being:
CAT status clear: Negligible lightning risk
CAT 1: Lightning detected within 1 km radius of sector
CAT 2: Lightning detected within 2 km radius of sector
Rarely used:
CAT 3: Lightning detected within 5 km radius of sector
CAT 4: Lightning detected within 8 km (unsure about that) radius of
sector
Till now, I have not heard of any CAT 5, but there could be.
