Understanding Typhoons and Their Categories

Typhoons are tropical cyclones that develop in the northwestern part of the Pacific Ocean, between 180° and 100°E
The term "bagyo" is a Filipino word meaning "typhoon" and emerged after a 1911 storm in Baguio city had record rainfall of 46 inches in 24 hours
Typhoons are categorized into five categories based on wind speed:
- Category 1: Tropical Depression - Sustains winds between 119 and 153 km/h
- Category 2: Tropical Storm (TS) - Winds between 154 and 177 km/h
- Category 3: Strong Typhoon - Winds between 178 and 209 km/h
- Category 4: Intense Typhoon (or Hurricane) - Sustains high winds of 210 to 249 km/h and is classified as a category-5 storm, which carries the highest element of risk
- Category 5: Violent Typhoon - Winds exceeding 249 km/h
Typhoon activity in the Philippines is strongest from July to October, with September being the most active month
Notable typhoons in the Philippines:
- Milenyo (Xangsane) - 2006
- Frank (Fengshen) - 2008
- Ondoy (Ketsana) - 2009
- Bebeng (Aere) - 2011
- Ambo (Mawar) - 2012
- Notable Typhoons that hit the Philippines in 2012: Ambo, Butchoy, Cosme, Dindo, Enteng, Frank, Gener, Helen, Igme, Siony, Tonyo, Yoyong, Zosimo, Julian, Karen, Lawin, Marce, Nina, Ofel, Pablo, Quinta, Rolly, Ulysses, Vicky, Warren

Pre-conditions for typhoon formation include:
- Monsoon Trough: An extension of the Inter-Tropical Convergence Zone (ITCZ) where cyclonic spin has developed. The ITCZ is a trough of low pressure created by the convergence of northeast and southeast trade winds.
- Tropical Upper Tropospheric Trough: The typical low pressure center that forms a typhoon starts at lower levels and is warmer than its surroundings
- Frontal Stall Over Tropical Water: A front has a cyclonic spin associated with it. Favorable winds aloft with little wind shear can lead to increased showers and storms, possibly forming a typhoon
- Mesoscale Convective Systems: Organized clusters of storms that can drift over warm waters. If they contain a small vortex, this can enhance the region’s suitability for tropical cyclone development

North Atlantic Ocean (June 1 - November 30): The most active period is from mid-August to late October. Impacts Caribbean, Bermuda, Central America, etc.
Eastern North Pacific Ocean (May 15 - November 30): The second most active region in the world. Storms mainly move into the eastern Pacific but can affect western Mexico and sometimes Hawaii.
Arabian Sea (April 1 - December 30): Has a double maximum due to the monsoon trough at different times of the year.
Southwest Pacific Ocean (October 15 - May 1): Tropical cyclones may affect eastern Australia.
Northwest Pacific Ocean (Typhoon) (Year-round): Most active basin in the world, with most typhoons forming between July and November. Can impact the Philippines, Southeast Asia, China, Taiwan and Japan.
Southeast Indian Ocean (October 15 - May): May affect northern and western Australia. Double maximum in mid-January and mid-February to early March.
Southwest Indian Ocean (October 15 - May 15): May affect Madagascar and southeastern Africa. Double maximum in mid-January and mid-February to early March

Formative Stage: The initial development of a tropical disturbance, characterized by the organization of thunderstorms and the formation of a low-pressure center.
Immature Stage: The tropical disturbance strengthens into a tropical depression or tropical storm with increasing wind speeds and a defined circulation.
Mature Stage: The typhoon reaches its peak intensity with well-defined structure, strong winds, and heavy rainfall
Decaying Stage: The typhoon weakens as it moves away from favorable conditions and eventually dissipates.

Buildings and Infrastructure: Wind and rainfall are the most destructive forces. Typhoon winds can damage buildings through direct force and projectiles. Persistent heavy rainfall can cause destructive flooding, making homes uninhabitable, roads impassable, and hindering rescue efforts.
Trees and Vegetation: Strong winds can uproot trees and cause widespread vegetation damage, potentially blocking roads, disrupting power lines, and impacting the natural environment.
Human Health: Flooding and landslides caused by typhoons can injure or kill people, while water-borne diseases can spread due to contaminated water.

Evacuation Plans: Preparedness for typhoon threats requires having evacuation plans in place to move people to safer areas before the storm hits.
Infrastructure Improvements: Strengthening buildings and structures to withstand strong winds and heavy rainfall is vital to mitigate damage, particularly in areas prone to typhoons.
Early Warning Systems: Accurate and timely weather forecasts and warning systems are crucial for allowing people to prepare and take appropriate actions, such as evacuating, securing property, and stocking up on essentials.
Sea Walls and Flood Control: Building seawalls and implementing effective flood control systems can help protect coastal areas from storm surges and reduce the risk of flooding.
Disaster Relief: Investing in and training teams for disaster relief is essential for providing aid and assistance to affected communities after a typhoon has passed.