Hydrometeorological Hazards

• Hydrometeorological hazard

  Hydro - water

  Meteorological - weather/atmosphere
• Hydrometeorological Hazard is

  • Processes or phenomena of atmosphere, hydrological, oceanographic nature.
  • Cause of life loss, either health, impacts, damages
• This hazard includes

  • Tropical cyclone
  • Thunderstorm
  • Hailstorm
  • Tornadoes
  • Cold Spells
  • Heavy Snowfall
  • Floods/Flashfloods
  • Drought
  • Heatwaves
  • Storm Surges
  • Avalanches
  • Blizzard
• National Oceanic and Atmospheric Administration (NOAA) shows that commonly known hazards are cyclone, typhoon, flood, storm, tornado, flashflood, thunderstorm and El Nino and La Nina.
• Cyclone

  • Powerful spinning storm that contain strong winds and rain.
  • Intense low pressure system
  • Counterclockwise flow in the hemisphere
• Classifications of cyclones are

  • Tropical Depression - max winds of 35 to 63 kmph
  • Tropical Storm - max winds of 64 - 118 kmph
  • Typhoon - max winds exceeding 118 kmph
• Typhoon

  • Large, powerful and violent tropical cyclone
  • Forms in warm water in the Pacific Ocean
  • Can inflict terrible damage (thunderstorm, violent winds, torrential rain, floods and landslides.)
• What they call Typhoon in other oceans

  • Atlantic Ocean - Hurricane
  • Indian Ocean - Cyclone
  • Australian Ocean - Wily-wily
• Thunderstorm

  • A weather condition producing thunder and lightning, heavy rainfall from cumulonimbus clouds and possibly a tornado.
  • A violent local disturbance.
• Cause of thunderstorms: Caused by convection as the air rising in the atmosphere heats up and becomes unstable. The air rises and called by expansion.
• Tornado

  • A violent rotating column of air extending from thunderstorm to the ground.
  • Form is visible condensation-funnel which is narrow.
  • Unstable air along ahead of cold-fronts developed from severe thunderstorm.
• Flash floods

  • Rapid flowing of geomorphic low lying areas (washes, rivers, dry lakes, basins)
• Common causes of flash floods are:

  1. Heavy rainfall with severe thunderstorm
  2. Tropical storm
  3. Melted water from ice
  4. Snow flowing over ice sheets/snowfields
  5. Hurricane
• Occurrence of flash floods

  • Flash floods may occur after collapse of a natural ice or debris dam, or a human structure such as man-made dams.
  • They are distinguished from regular floods by a timescale of less than six hours.
• Flood are inundation of land areas not normally covered by water. It is the temporary rise of water-overflowing of a river, streams as the inundation of adjacent lands or flood plains.
• Two elements of floods

  Intensity - rate of flood

  Duration - how long
• Storm Surge is the rise of seawater above normal sea level over the coast generated by the action of weather elements such as Cyclonic wind and Atmospheric pressure.
• Storm surges are "laging dala ng bagyo" or "daluyong ng bagyo"
• El Nino and La Nina are weather patterns resulting from variations in ocean temperature in equatorial pacific.
• El Nino and La Nina are two phenomena that are opposite phases of what is known as the:

  El Nino Southern Oscillation (ENSO) cycle
• ENSO cycle

  • a scientific term that describes the flunctuations of temperature between the ocean and the atmosphere in the East central Equatorial Pacific.
• Phases of ENSO cycle

  El Nino - Warm phase, occurs more than La Nina

  La Nina - Cold phase
• Signs of an impending hurricane/typhoon

  96 hours before landfall

  • No apparent signs
  • Barometer is steady
  • Fair weather cumulus clouds appear
• Signs of an impending hurricane/typhoon

  72 hours before landfall

  • Little change
  • Swell on the ocean surface: increased about six feet and waves come in every 9 seconds
• Signs of an impending hurricane/typhoon

  48 hours before landfall

  • Sky is clear of clouds
  • Barometer is steady
  • Almost steady wind
  • Swell is now 9 feet and coming in 8 seconds
• Signs of an impending hurricane/typhoon

  36 hours before landfall

  • First sign of the storm appear
  • Barometer is falling slightly
  • 11 mph wind
  • Swell is 13 feet and coming in 7 seconds
  • Large mass of white cirrus clouds appear. Veil of clouds approaches covers more of the horizon.
  • Hurricane watch is issued, giving order to begin evacutation
• Signs of an impending hurricane/typhoon

  30 hours before landfall

  • Sky is covered by high overcast
  • Barometer is falling at 0.1 millibar per hour
  • 23 mph wind
  • Swelling of ocean coming in 5 seconds, small whitecaps begin on the ocean surface.
• Satellite is the most advance technology used in monitoring a typhoon/cyclone. It can visualize exactly in real time the formation and path of a cyclone.
• Doppler Radar (Radio Detection & Ranging)

  • Radio detection device that emit and receive radio waves to determine the distance it takes for the wave to return.