Hydrometeorological Hazards

• Intertropical Convergence Zone (ITCZ)


  Area near the equator where trade winds meet
• Philippines is in the Northern Hemisphere, which is above the equator
• Hydro-meteorological hazards


  Processes or phenomena of atmospheric, hydrological or oceanographic nature
• Typhoon


  A large, powerful and violent tropical cyclone that is a low pressure area rotating counter-clockwise and containing rising warm air that forms over warm water in the Western Pacific Ocean
• Classification of Tropical Cyclones

  • Tropical depression (TD): up to 61 kph
  • Tropical storm (TS): 62 to 88 kph
  • Severe tropical storm (STS): 89 to 117 kph
  • Typhoon (TY): 118 to 220 kph
  • Super typhoon (STY): exceeding 220 kph
• Thunderstorm


  Also known as electrical storm, a storm characterized by heavy rain with the presence of lightning
• Flood


  The presence of excessive water on a supposedly dry land, can be caused by continuous heavy rain or poor drainage
• Flash Flood


  A rapid flow of water on saturated soil or dry soil or any foundation that has poor absorption capability, caused by extensive rainfall but can also be induced by man-made structures such as water overflows from a dam
• Storm Surge


  An abnormal rise in coastal waters due to a massive force from the sea or from the air above the sea, can be caused by a strong typhoon or a sea quake, can instantly flood coastal areas, and can also be aggravated by the occurrence of high tide
• Tornado and Whirlwind 


  A rapidly rotating column of air that is in contact with the air and land, an average of 12-14 tornadoes hit the country every year, tornadoes form when there are strong winds and low thunderstorm clouds
• El Niño


  A natural part of the global climate systems, refers to the large-scale warming of the ocean and atmosphere across the central and east-central Equatorial Pacific, begins with the heating up of the Pacific Ocean near the equator
• La Niña


  A natural part of the global climate systems, begins in the eastern part of the Pacific Ocean, much similar to the location of El Niño, the sea surface temperatures during this period become lower by 3-5 degrees Celsius
• PSWS No. 1

  A weather disturbance is in the locality, and winds of up to 60 km/hour are expected within 36 hours. Classes in the pre-school are suspended.
• PSWS No. 2

  May affect the locality, and winds of 60 to 100 km/hour may be expected within the next 24 hours. Classes in the elementary and high school levels are suspended.
• PSWS No. 3

  May be dangerous to the locality, and winds over 100 km/hour may be expected within 18 hours. Classes in all levels are suspended.
• PSWS No. 4

  May be dangerous and destructive, winds of more than 185 km/hour may be expected in less than 12 hours. All schools are closed.
• PSWS No. 5

  Very destructive, winds of more than 220 km/hour may be expected within 12 hours. No schools or businesses should be in operation.
• Doppler radar

  used to measure important weather parameters such as amount of rainfall and direction, speed, and intensity of winds
• Automated rain gauge

  usually installed in telecommunication cell sites to observe and locate areas with excessive amount of rainfall