Tropical Cyclone Hazards & Preparedness

1. To insert your company logo on this slide • From the Insert Menu • Select “Picture” • Locate your logo file • Click OK • To resize the logo • Click anywhere inside the logo. The boxes that appear outside the logo are known as “resize handles.” • Use these to resize the object. • If you hold down the shift key before using the resize handles, you will maintain the proportions of the object you wish to resize. Tropical Cyclone Hazards & Preparedness David Michael V. Padua(Typhoon2000.com)

2. What is a Tropical Cyclone? • A Tropical Cyclone is the global generic term for an intense low-pressure system over tropical or sub-tropical oceans with organized cloud convection (i.e. thunderstorm activity) and definite cyclonic surface wind circulation.(Holland 1993)

3. How do Tropical Cyclones Form? • Warm SST of at least 26.5°C with a depth of 150 feet & high moisture/ humidity present in the air. 2. Presence of ITCZ. 3. Existence of LPA or Tropical Disturbance. 4. Weak shear or light winds in the upper atmosphere.

5. Death & Dissipation of Tropical Cyclones (TCs) • TCs die when: • They leave the environment of warm, moist tropical air; (2) They move over a large land mass, & (3) When they travel over cooler sea surface temperatures (ssts) or under unfavorable large scale circulation of air currents at high levels in the earth’s atmosphere (eg. strong vertical wind shear).

6. Energy of a Tropical Cyclone • The fantastic energy of a Tropical Cyclone is remarkable! - consider for example, that an ordinary afternoon thunderstorm (which lasts for 1 to 2 hrs.) has the energy equivalent of about 13, 20-kiloton atomic bombs - a small typhoon carrying winds of 120 kph has an energy equivalent of almost 500,000 atomic bombs, or about 6 atomic bombs per second! A typhoon also releases about20 billion tons of water.

7. Movement & Speed of Tropical Cyclones (TCs) • In the Philippine Sea, TCs tend to move on a general west-northwest (WNW) direction with an avg speed of 19-20 kph. TCs tend to move under the influence of both Internal and External Forces. Internal – arises within the circulation of the TC itself, while, External are applied by the steering flows (steering air currents) of High Pressure Areas that surround the TC on all sides and “carry it along” like “a cork floating in the river stream.”

11. Types of Tropical Cyclone • TROPICAL DEPRESSION -a tropical cyclone with maximum sustained winds of 45 to 61 kph. Its circulation is still scattered & less organized.

12. REMING (DURIAN) as a Tropical Depression…Nov 26, 2006

13. Types of Tropical Cyclone • TROPICAL STORM -a tropical cyclone with maximum sustained winds ranging from 62 to 117 kph. Circulation becoming more organized.

14. REMING (DURIAN) as a Tropical Storm…Nov 28, 2006

15. Types of Tropical Cyclone • TYPHOON / HURRICANE / CYCLONE • a tropical cyclone with maximum sustained winds ranging from 118 to 239 kph. Its circulation is now purely organized with an “eye” at the center.

17. Types of Tropical Cyclone • Super Typhoon -a special type of tropical cyclone / typhoon with maximum sustained winds of more than240 kph.

18. Outer (Feeder) Bands EYE EyeWall Inner (Rain) Bands

19. Parts of a Typhoon 1. OUTER (FEEDER) BANDS – is the outer spiral bands of a typhoon w/c are scattered but moving inward. It is characterized by occasional light to moderate rainfall with light to moderate winds blowing. Sunlight may still penetrate at these bands (50% cloud cover). 2. INNER (RAIN) BANDS – defined as the inner or main spiral bands of a typhoon w/c are now organized & not scattered as it moves inward towards the center. It is characterized by moderate intermittent rains with increasing wind velocity. 90% of the sky covered with high clouds.

20. Parts of a Typhoon 3. EYE WALL (wall cloud) – an organized band of clouds immediately surrounding the center or “eye” of a typhoon. It is the area of most violent winds, heaviest rainfall & greatest release of heat energy. This “ring” of violent winds & torrential rains is usually 8 to 40 km from the storm’s center or “eye.” 4. The “EYE” – it is here, where the lowest pressure can be found. The relatively calm part of the typhoon with sometimes light winds (of up to 20 kph) blowing. The sky may be just partly cloudy w/ intermittent burst of blue sky through the thin clouds. Average “eye” diameter is about 30 km.

21. Typhoon’s Horizontal View

22. Size of a Typhoon • Vertical Extent: a typhoon’s vertical size can reach a height of 40,000 to 50,000 feet above sea level. • Horizontal Extent: a typhoon’s horizontal size can reach a maximum of 1,500 km in diameter & a minimum of 200 km. Avg size is about 600 km. • Examples: largest ever recorded STY TIP (Oct 1979) – 2,200 km in diameter. Smallest was TC TRACY in Australia – 100 km.

35. REMING (DURIAN) as a Typhoon…7:30 AM Nov 29, 2006

36. REMING (DURIAN) as a Super Typhoon…Nov 29, 2006

37. STY REMING (DURIAN) undergoes Eyewall Replacement...8 AM Nov 30, 2006

38. STY REMING (DURIAN) prepares to make landfall...11 AM Nov 30, 2006

39. STY REMING (DURIAN) starts to landfall off Tiwi-Buhi Area...12 PM Nov 30, 2006

40. STY REMING (DURIAN) makes landfall off Tiwi-Buhi Area...1 PM Nov 30, 2006

41. STY REMING (DURIAN) over Iriga City-Nabua Area...3 PM Nov 30, 2006

42. STY REMING (DURIAN) over Western Pili-Pasacao Area...4 PM Nov 30, 2006

46. Summary of Tropical Cyclone Types

47. The Philippine Storm Warning Signals - Storm warning signals are used to inform the public regarding on how strong a tropical cyclone will affect the area.

48. 4 Levels of Storm Warning Signals • PUBLIC STORM WARNING SIGNAL # 1 - Winds of30 - 60 kphmay be expected in at least 36 hoursor

49. 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.

50. When the tropical cyclone is strong or is intensifying and is moving closer, this signal may be upgraded to the next higher level.