MANILA - Authorities are warning of storm surges and destructive winds brought by Typhoon Ompong (international name: Mangkhut) as it places two areas under the second highest tropical cyclone warning signal.

State weather bureau PAGASA placed Cagayan and northern Isabela under Tropical Cyclone Warning Signal No. 4 Friday as winds of 171 to 220 kilometers per hour (kph) were expected to be felt within the next 12 hours.

• Signal no. 4 up in Cagayan, northern Isabela as Ompong approaches

But what kind of destruction should Filipinos brace for under each storm signal? Here is a guide from the Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA).

Signal # 4:

• Very heavy damage to high–risk structures
• Heavy damage to medium risk structures;
• Moderate damage to low-risk structures
• Considerable damage to structures of light materials (up to 75% are totally and partially destroyed); complete roof structure failures.
• Many houses of medium-built materials are unroofed, some with collapsed walls; extensive damage to doors and windows
• A few houses of first-class materials are partially damaged
• All signs/billboards are blown down. There is almost total damage to banana plantation
• Most mango trees, ipil-ipil and similar types of large trees are downed or broken.
• Coconut plantation may suffer extensive damage.
• Rice and corn plantation may suffer severe losses.

Storm surge of 2-3 meters possible at coastal areas

Signal # 3:

• Heavy damage to high–risk structures;
• Moderate damage to medium-risk structures;
• Light damage to low risk structures
• Increasing damage (up to more than 50%) to old, dilapidated residential structures and houses of light materials. Majority of all nipa and cogon houses may be unroofed or destroyed
• Houses of medium strength materials (old, timber or mixed timber-CHB structures, usually with G.I. roofing’s); some warehouses or bodega-type structures are unroofed.
• There may be widespread disruption of electrical power and communication services.
• Almost all banana plants are downed.
• Some big trees (acacia, mango, etc.) are broken or uprooted.
• Dwarf-type or hybrid coconut trees are tilted or downed.
• Rice and corn crops may suffer heavy losses.
• Damage to shrubbery and trees with foliage blown off; some large trees blown down.

Signal # 2:

• Light to Moderate damage to high risk structures;
• Very light to light damage to medium-risk structures;
• No damage to very light damage to low risk structures
• Unshielded, old dilapidated schoolhouses, makeshift shanties, and other structures of light materials are partially damaged or unroofed.
• A number of nipa and cogon houses may be partially or totally unroofed.
• Some old galvanized iron (G.I.) roofs may be peeled or blown off.
• Some wooden, old electric posts are tilted or downed.
• Some damage to poorly constructed signs/billboards
• In general, the winds may bring light to moderate damage to the exposed communities. Most banana plants, a few mango trees, ipil-ipil and similar types of trees are downed or broken.
• Some coconut trees may be tilted with few others broken.
• Rice and corn may be adversely affected.
• Considerable damage to shrubbery and trees with some heavy-foliaged trees blown down.

Signal # 1

• Very light or no damage to low risk structures,
• Light damage to medium to high risk structures
• Slight damage to some houses of very light materials or makeshift structures in exposed communities. Some banana plants are tilted, a few downed and leaves are generally damaged
• Twigs of small trees may be broken.
• Rice crops, however, may suffer significant damage when it is in its flowering stage.

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