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• A typhoon is a severe weather disturbance characterized by strong winds and heavy rains which revolve around a central low pressure area.
• A typhoon is the most powerful type of tropical cyclone that forms in the northwestern Pacific Ocean.
• A typhoon is one of three types of tropical cyclones, which can be distinguished according to their maximum sustained-wind speed (over 10- minute periods).
• Tropical Depression has wind speed up to 62kph.
• Tropical Storm has wind speed ranging from 63-118kph.
• Typhoon has wind speed greater than 118kph and is called hurricane in northeast Pacific and northern Atlantic regions.
• A typhoon can be categorized as super typhoon with wind speed exceeding 220 kph.
• Tropical cyclone activity is usually lowest in May and increases gradually through June.
• Tropical cyclone activity greatly increases from July until September, with the level of activity reaching its highest during August.
• Tropical cyclone activity eventually dies off by November.
• The SOI indicates whether an El Niño or La Niña events will take place in the Pacific Ocean.
• PAGASA categorizes El Niño and La Niña events based on sea surface temperature anomalies (SSTAs).
• El Niño and La Niña occur alternatingly and usually recur every 3–5 years but can range from 2 to 7 years.
• El Niño and La Niña both usually develop during March–June, reach maximum intensity during December–April, and eventually weaken during May–July.
• An ENSO-neutral is a period when neither an El Niño nor a La Niña occurs.
• ENSO-neutral periods usually occur during the transition between El Niño and a La Niña.
• During an ENSO-neutral, sea surface temperatures (tropical precipitation amount and patterns, and atmospheric wind patterns in the equatorial Pacific Ocean) are close to the long-term average conditions.
• The term El Niño was adapted for the phenomenon it was named after.
• El Niño is differentiated from La Niña.
• El Niño events are more frequent than La Niña events.
• Farmers can protect their livelihood from the effects of El Niño and La Niña by implementing mitigation measures such as crop diversification and drought-resistant crop varieties.
• Government agencies implement mitigation measures for El Niño and La Niña, including providing disaster relief and implementing early warning systems.
• Tropical cyclones form as a result of the atmosphere’s natural tendency to maintain equilibrium by redistributing heat through wind from the equatorial regions to the polar regions.
• Rainfall brought about by tropical cyclones replenishes ground water and surficial water.
• Flora and fauna in the Philippines are heavily reliant on tropical cyclones for source of water.
• Tropical cyclones facilitate the redistribution of heat which prevents the tropical areas from getting excessively hot and the polar regions from becoming extremely cold.
• Strong winds, which cover a much larger area during tropical cyclones, cause the most obvious damage.
• Flooding is the abnormal rise of water level in rivers, coastal areas, plains, and in highly urbanized centers which may be a result of natural phenomena, human activities, or both.
• Flooding duration can be as short as a few minutes but can take as long as several days or even weeks to subside.
• Flooding can be a natural process and can be the result of man’s inadvertence.
• Some areas, due to their location, land configuration, and climactic setting, are naturally susceptible to flooding.
• Riverine flood happens when the level of water owing through rivers increases and goes beyond the average water level, or worse, further encroaches levee.
• Water levels usually rise slowly in larger rivers with large catchment areas and rise more rapidly in smaller rivers which have smaller catchment areas.
• Extreme and sustained rainfall is one cause of riverine flooding.
• Estuarine and Coastal flood occurs when seawater encroaches low-lying land that is usually still above sea level.
• Flooding in these areas can be a result of storm surges and can also be caused by unusually high tides.
• When an astronomical high tide coincides with the occurrence of a tropical cyclone, flooding is aggravated and can cause far more damage.
• Urban flooding usually occurs in highly populated, developed areas set on relatively low-lying areas like valleys and plains.
• Urban flooding is largely due to man-made causes like lack of proper drainage systems, obstruction of waterways by solid industrial material, household wastes, wrongly situated settlements.
• Catastrophic flooding may result from ground failure, the weakening of the rock or soil such as subsidence, liquefaction, and occurrence of landslides that may be triggered by earthquakes, volcanic eruptions, intense rainfall, and other natural disasters.