How destructive is storm signal number 4?

ABS-CBN News

Posted at Sep 14 2018 07:03 PM | Updated as of Sep 14 2018 08:30 PM

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.

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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