UNDERSTANDING TYPHOONS

UNIT 2Module 2

Trivia Question: We hear weathercasters talk about typhoons, hurricanes and cyclones – so what’s the difference?

a)    Typhoons are bigger than cyclones; cyclones are bigger than hurricanes.

b)    Hurricanes are stronger than typhoons and cyclones.

c)    Hurricanes, typhoons and cyclones occur in different geographical areas.

The correct answer is c. 

Typhoons, cyclones and hurricanes are the same weather phenomenon – the difference is the geographical area where they occur. They are tropical cyclones with regionally specific names.

In 1963 by the Philippine Weather Bureau through the use of four sets of alphabetically arranged Filipino women nicknames ending in “ng” that are alternately used every four years. In 1999, the Philippine Atmospheric, Geophysical and Astronomical Services (PAGASA) held a nationwide search for new generation tropical cyclone names. It was dubbed as “Name the Bagyo Contest.” The result of the search which was picked out from more than 18,000 entries was 140 no-gender-bias names that will be used until 2016 by PAGASA.

Did you know that?

According to the Philippine Atmospheric, Geophysical, and Astronomical Services Administration (PAGASA), about 20 tropical cyclones enter the Philippine Area of Responsibility each year.

Did you know that?

WHAT CAN YOU SAY?Describe the picture…

What is a typhoon?

Winds in a typhoon move in a certain direction; they go around a central area.

The appearance of the clouds in a typhoon are in a spiral arrangement; they are being blown by winds in a counter-clockwise direction.

CATEGORY MAXIMUM WIND SPEED

KILOMETERS PER HOUR (kph)

Tropical Depression 64

Tropical Storm 118

Typhoon 200

Supertyphoon Greater than 200

Tropical Cyclone Signals

The term typhoon is used only in the northwestern part of the Pacific Ocean.

In the northeastern part of the Pacific Ocean and in the northern part of the Atlantic ocean, the equivalent term is hurricane.

PAR(Philippine Area of

Responsibility)

Points Latutude, Longitude

A 5oN, 115oEB 15oN, 115oEC 21oN, 120oED 25oN, 120oEE 25oN, 135oEF 5oN, 135oE

POINTS OF THE PAR

Q1. If a typhoon is located at 15oN,138oE, is it within the PAR?

Q2. How about if the typhoon is at 19oN, 117oE, is it inside the PAR?

Can you answer these questions?

Harurot, 2003

Agaton, 2002

Yoyong, 2004 Huaning, 2005

Q1. Where did the tropical cyclone form? On land or in the ocean?

Q2. What can you say about the temperature of the bodies of water in the vicinity of the Philippines? Is the water warm or cold?

Can you answer these questions?

Q3. In what direction did the tropical cyclones move?

Q4. Which part of the Philippines was hit by the four tropical cyclones?

Can you answer these questions?

Q5. In the case of Agaton, Yoyong, and Huaning, where did they die out? Near land or in the middle of the ocean?

Can you answer these questions?

Tropical cyclones need water vapor in order to form.

Tropical cyclones require warm ocean waters to be able to develop. (26.5oC or greater)

Tropical cyclones generally move in a northwest direction.

When tropical cyclones reach land, they die out because they are cut off from the warm ocean waters that keep them going.

INSIDE TROPICAL CYCLONES

• The lowest air pressure is at the eye of a tropical cyclone

• At the eye of a tropical cyclone, wind speed is low.

• At the eyewall, the wind speed is great.

• When the eye of a tropical cyclone passes over a certain place, it is the winds at the eyewall that wreak a lot of damage.

PUBLIC STORM WARNING SIGNALS

PSWS # 1METEOROLOGICAL CONDITIONS:A tropical cyclone will affect the locality.Winds of 30-60 kph may be expected in at least 36 hours or intermittent rains may be expected within 36 hours.

WHAT TO DO:Inspect your house if necessary repair/fixing is needed.Clean up drainage system.Harvest crops that can be yielded.Monitor the latest Severe Weather Bulletin issued By PAGASA every six hours and hourly updates.

PSWS # 1

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.

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.

PSWS # 1

The people are advised to listen to the latest severe weather bulletin issued by PAGASA every six hours. In the meantime, business may be carried out as usual except when flood occur.Disaster preparedness is activated to alert status.

PRECAUTIONARY MEASURES:When the tropical cyclone is strong or is intensifying and is moving closer, this signal may be upgraded to the next higher level.The waves on coastal waters may gradually develop and become bigger and higher.

PSWS # 2

WHAT TO DO:Prepare flashlights, batteries , matches, kerosene lamps, or candles and charcoal in anticipation of power failure, first aid kit and store ready to eat foods.Keep your cell phones fully charged.Elevate household things in case of flooding.For fishing folks, secure fishing boats in safe area.

METEOROLOGICAL CONDITIONS:A tropical cyclone will affect the the locality.Winds of greater than 60 kph and up to 100 kph may be expected in at least 24 hours.

PSWS # 2

Large number of nipa and cogon houses may be partially or totally unroofed.Some old galvanized iron roofings may be peeled off.In general, the winds may bring light to moderate damage to the exposed communities.

IMPACT OF THE WINDS:Some coconut trees may be tilted with few others broken.Few big trees may be uprooted.Many banana plants may be downed.Rice and corn may be adversely affected.

PSWS # 2

The general public especially people travelling by sea and air are cautioned to avoid unnecessary risks.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.

PRECAUTIONARY MEASURES:The sea and coastal waters are dangerous to small seacraftsSpecial attention should be given to the latest position, the direction and speed of movement and the intensity of the storm as it may intensify and move towards the locality.

PSWS # 3METEOROLOGICAL CONDITIONS:A tropical cyclone will affect the locality.Winds of greater than 100 kph up to 185 kph may be expected in at least 18 hours. 

PSWS # 3WHAT TO DO:If the house is not strong enough to withstand the battering of strong winds go to designated evacuation center aor seek shelter in stronger houses.Stay in safe houses until after the disturbances has left the area. 

Evacuate from low-lying area and reiverbanks and stay away from coastal areas for possible flooding and strom surge.All travel and outdoor activities should be cancelled.Watch out for the passage of the "Eye Wall and the "Eye" of the typhoon.

PSWS # 3 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 all nipa and cogon houses may be unroofed or destroyed and 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.

PSWS # 3 PRECAUTIONARY MEASURES:The disturbance is dangerous to the communities threatened/affected.The sea and coastal waters will be very dangerous to all seacrafts.Travel is very risky especially by sea and air. 

People are advised to seek shelter in strong buildings, evacuate low-lying areas and to stay away from the coasts and river banks.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.

PSWS # 3 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 actual emergency.

PSWS # 4 METEOROLOGICAL CONDITIONS:A very intense typhoon will affect the locality.Very strong winds of more than 185 kph may be expected in at least 12 hours. 

PSWS # 4WHAT TO DO:If the house is not strong enough to withstand the battering of strong winds go to designated evacuation center aor seek shelter in stronger houses. 

Stay in safe houses until after the disturbances has left the area.Evacuate from low-lying area and reiverbanks and stay away from coastal areas for possible flooding and strom surge.All travel and outdoor activities should be cancelled.Watch out for the passage of the "Eye Wall and the "Eye" of the typhoon.

PSWS # 4IMPACT OF THE WINDS:Coconut plantation 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.In the overall, damage to affected communities can be very heavy.

PSWS # 4PRECAUTIONARY 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 since it may be too late under this situation. 

With PSWS #4, the locality is very likely to be hit directly by the eye of the typhoon. As the eye of the typhoon approaches, the weather will continuously worsen with the winds increasing to its strongest coming generally from the north.

PSWS # 4Then a sudden improvement of the weather with light winds (a lull) will be experienced. This means that the eye of the typhoon is over the locality. This improved weather may last for one to two hours depending on the diameter of the eye and the speed of movement. 

As the eye moves out of the locality, the worst weather experienced before the lull will suddenly commence. This time the very strong winds will come generally from the south.

PSWS # 4

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.