Thunderstorm and
 Public Storm Warning Signal

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Thunderstorm

A rain-bearing cloud that also produces lightning. it is a transient storm of lightning and thunder. A thunderstorm is a storm with lightning and thunder. Its produced by a cumulonimbus cloud, usually producing gusty winds, heavy rain and sometimes hail. A thunderstorm is a storm with lightning and thunder. Its produced by a cumulonimbus cloud, usually producing gusty winds, heavy rain and sometimes hail. A thunderstorm is classified as “severe” when it contains one or more of the following: hail one inch or greater, winds gusting in excess of 58 mph (50 knots), or a tornado.

Public Storm Warning Signal

Signal no.1

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METEOROLOGICAL CONDITIONS:

  • A tropical cyclone will threaten/affect an area.
  • Winds of 30-60 kph is expected.
  • Intermittent rains may be expected in at least 36 hours. (When the tropical cyclone develops very close to an area, a shorter lead time of the occurrence of the winds will be specified in the warning bulletin.)

IMPACT OF THE WINDS:

  • Twigs and branches of small trees may be broken.
  • Some banana plants may be tilted or uprooted.
  • Some houses of very light materials may be partially unroofed.
  • Only very light or no damage may be sustained by areas affected.
  • Rice crops in flowering stage may suffer significant damage.

PRECAUTIONARY MEASURES:

  • When the tropical cyclone intensifies and moves closer, this warning signal number may be upgraded.
  • The waves on coastal waters may gradually develop and swell.
  • The people are advised to listen to the latest severe weather bulletin issued by PAGASA every six hours.
  • Business may be carried out as usual except when floods occur.
  • Disaster preparedness units are activated to alert status.

    A tropical cyclone will affect the locality.

    -  Winds of 30 - 60 kilometers per hour (kph) may be expected in at least 36
        hours or intermittent rains may be expected within 36 hours. (When the
        tropical cyclone develops very close to the locality - a shorter lead time of the
        occurrence of the winds will be specified in the warning bulletin


    Impact of the Winds

      • -   Twigs and branches of small trees may be broken.

        -   Some banana plants may be tilted or downed.

        -   Some houses of very light materials (nipa and cogon) may be partially unroofed.

        -   Unless this warning signal is upgraded during the entire existence of the tropical
            cyclone,  only very light or no damage at all may be sustained by the exposed
            communities.

        -   Rice crop, however, may suffer significant damage when it is in its flowering
            stage.


Signal no.2

DAMAGE TO STRUCTURE:

  • 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.
  • 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.

DAMAGE TO VEGETATION:

  • Most banana plants, a few mango trees, ipil-ipiland similar 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.

METEOROLOGICAL CONDITIONS:

  • A tropical cyclone will affect an area.
  • Winds of greater than 60 kph and up to 100 kph may be expected in at least 24 hours.

IMPACT OF THE WINDS:

  • Some coconut trees may tilt; some of them may break.
  • Few big trees may be uprooted.
  • Many banana plants may be downed.
  • Rice and corn crops may be affected.
  • A large number of houses made of light materials may be unroofed.
  • Old galvanized iron roofing may be peeled off.
  • In general, the winds may bring light to moderate damage to the exposed communities.

PRECAUTIONARY MEASURES:

  • The sea and coastal waters are dangerous to small seacraft.
  • Special attention should be given to the latest position, direction and movement speed, and intensity of the storm as it moves toward an area.
  • The public especially people traveling by sea and air are cautioned.
  • Outdoor activities of children should be postponed.
  • Secure properties before the signal is upgraded.
  • Disaster preparedness agencies/organizations are in action to alert their communities.

Signal no.3

DAMAGE TO STRUCTURE:

  • Heavy damage to high–risk structures;
  • Moderate damage to medium-risk structures;
  • Light damage to low-risk structures
  • Increasing damage to old, dilapidated residential structures and houses of light materials (up to 50% in a community)
  • Houses of medium strength materials (old, timber or mixed timber-CHB structures, usually with G.I. roofings), some warehouses or bodega-type structures are unroofed,

DAMAGE TO VEGETATION:

  • 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
  • Considerable damage to shrubbery and trees with heavy foliage blown off; some large trees blown down.

METEOROLOGICAL CONDITIONS:

  • A tropical cyclone will affect an area.
  • Winds of greater than 100 kph up to 185 kph may be expected in at least 18 hours.

IMPACT OF THE WINDS:

  • Many coconut trees may be broken or destroyed.
  • Almost all banana plants may be downed and a large number of trees may be uprooted.
  • Rice and corn crops may suffer heavy losses.
  • Majority of light material houses may be unroofed or destroyed. There may be considerable damage to structures of light to medium construction.
  • There may be widespread disruption of electrical power and communication services.
  • In general, moderate to heavy damage may be experienced, particularly in the agricultural and industrial sectors.

PRECAUTIONARY MEASURES:

  • The weather condition is dangerous to the communities affected.
  • The sea and coastal waters will be very dangerous to all seacraft.
  • Travel is very risky especially by air and sea.
  • People are advised to seek shelter in strong buildings, evacuate low-lying areas, and stay away from the coasts and riverbanks.
  • Watch out for the passage of the eye of the typhoon indicated by a sudden occurrence of fair weather immediately after very bad weather, with very strong winds coming generally from the north.
  • When the eye of the typhoon hit the community, do not venture away from the safe shelter because after one to two hours, the worst weather will resume, with the very strong winds coming from the south.
  • Classes in all levels should be suspended and children should stay in the safety of strong buildings.
  • Disaster preparedness and response agencies/organizations are in action with appropriate response to emergency.

Signal no.4

DAMAGE TO STRUCTURE:
  • 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.

DAMAGE TO VEGETATION:
  • There is almost total damage to banana plantation,
  • Most mango trees, ipil-ipiland similar types of large trees are downed or broken.
  • Coconut plantation may suffer extensive damage.
  • Rice and corn plantation may suffer severe losses.

METEOROLOGICAL CONDITIONS:

  • A very intense typhoon will affect the area.
  • Very strong winds of more than 185 kph may be expected in at least 12 hours.

IMPACT OF THE WINDS:

  • Coconut plantations may suffer extensive damage.
  • Many large trees may be uprooted.
  • Rice and corn plantation may suffer severe losses.
  • Most residential and institutional buildings of mixed construction may be severely damaged.
  • Electrical power distribution and communication services may be severely disrupted.
  • Damage to affected communities can be very heavy.

PRECAUTIONARY MEASURES:

  • The situation is potentially very destructive to the community.
  • All travels and outdoor activities should be cancelled.
  • Evacuation to safer shelters should have been completed.
  • The area is very likely to be hit directly by the eye of the typhoon.
  • As the eye of the typhoon approaches, the weather will worsen continuously, with winds increasing to its strongest coming generally from the north.
  • A sudden improvement of the weather with light winds will be experienced, which means the area is under the eye of the typhoon.
  • Depending on the eye’s diameter and movement speed, this improved weather may last for an hour or two.
  • As the eye moves out of the area, weather conditions will worsen, with strong winds generally coming from the south.
  • The disaster coordinating councils concerned and other disaster response organizations are now fully responding to emergencies.

Signal no.5

DAMAGE TO STRUCTURE:

  • Widespread damage to high-risk structures
  • Very heavy damage to medium-risk structures
  • Heavy damage to low-risk structures;
  • Almost total damage to structures of light in highly exposed coastal areas.
  • Complete roof failure on many residences and industrial buildings. Severe and extensive window and door damage
  • Most residential and institutional buildings of mixed construction may be severely damaged.
  • Electrical power distribution and communication services severely disrupted.
  • All signs/billboards blown

DAMAGE TO VEGETATION:

  • Total damage to banana plantation
  • Most tall trees are broken, uprooted or defoliated;
  • Coconut trees are stooped, broken or uprooted.
  • Few plants and trees survived.

METEOROLOGICAL CONDITIONS:

  • A Super Typhoon will affect the area.
  • Very strong winds of more than 220 kph may be expected in at least 12 hours.

IMPACT OF THE WINDS:

  • Almost total damage to structures of light materials, especially in highly exposed coastal areas.
  • Complete roof failure on many buildings. Severe and extensive window and door damage.
  • Most residential and institutional buildings of mixed construction may be severely damaged.
  • Electrical power distribution and communication services severely disrupted.
  • All signboards blown down.
  • Total damage to banana plantation.
  • Most tall trees are broken, uprooted, or defoliated.
  •   Coconut tress are stooped, broken, or uprooted.
  • Few plants and tress survived.

PRECAUTIONARY MEASURES:

  • The situation is potentially extremely destructive or catastrophic to the community.
  • All travels and outdoor activities should be cancelled.
  • Evacuation to safer shelters should have been completed since it may have been too late for this situation.
  • The area is very likely to be hit directly by the eye of the typhoon.
  • As the eye of the typhoon approaches, the weather will worsen continuously, with winds increasing to its strongest coming generally from the north.
  • A sudden improvement of the weather with light winds will be experienced, which means the area is under the eye of the typhoon.
  • Depending on the eye’s diameter and movement speed, this improved weather may last for an hour or two.
  • As the eye moves out of the area, weather conditions will worsen, with strong winds generally coming from the south.
  • The disaster coordinating councils concerned and other disaster response organizations are now fully responding to emergencies and in full readiness to immediately respond to possible calamity..

References:

pagasa.dost.gov.phofficialgazette.gov.ph/

kidlat.pagasa.dost.gov.ph

officialgazette.gov.ph/laginghanda/the-philippine-public-storm-warning-signals/