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• Hydrometeorological hazard

  A process or phenomenon of atmospheric, hydrological or oceanographic nature that may cause loss of life, injury or other health impacts, property damage, loss of livelihoods and services, social and economic disruption, or environmental damage
• Hydrometeorological hazards


  • Typhoon
  • Thunderstorm
  • Flood
  • Flashflood
  • Storm Surge
  • El Niño
  • La Niña
• Hydrometeorological conditions lead to other hazards such as landslides, fires, plagues, epidemics and in transport and dispersal of toxic substances and volcanic eruption material
• Typhoon


  • A violent tropical cyclone that forms over warm waters
  • Contains winds rotating counterclockwise with a speed of 118-220 kilometers per hour. It could also develop into a super typhoon if the wind speed exceeds 220 kilometers per hour
  • Tropical cyclone, also called typhoon or hurricane, an intense circular storm that originates over warm tropical oceans and is characterized by low atmospheric pressure, high winds, and heavy rain
• Increased ocean swell

  • A swell is a series of ocean waves brought about by strong winds
  • An incoming typhoon would cause a swell on about a meter in height that hit the shore every 10 seconds
• Changes in clouds


  • Cumulus clouds may fill the sky about 36 hours before a typhoon
• Barometric pressure drop


  • The atmospheric pressure may start to drop about 36 hours before the typhoon landfall
  • This would continue as the storm approaches
• Abrupt changes in wind speed


  • Wind speed increases due to the drop in atmospheric pressure
  • The increase in wind speed also increases the height of the ocean swell
• Tropical cyclone


  • Also called as typhoon or hurricane
  • An intense storm that originates over warn tropical oceans and is characterized by low atmospheric pressure, high winds, and heavy rain
• Thunderstorm


  • A powerful, short-lived weather disturbance, almost always associated with lightning, thunder, dense clouds, heavy rain or hail, and fast, roaring winds
  • Thunderstorms occur when layers of dry, moist air rise to cooler regions of the atmosphere in a broad, rapid updraft
• Thunderstorm formation


  1. Cumulus stage: Sun heats the Earth's surface during the day and warms the air around it

  2. Mature stage: Cumulus cloud becomes very large, where the water therein becomes large and heavy, and raindrops begin to fall through the cloud when the rising air can no longer hold them up

  3. Dissipating stage: After 30 minutes, thunderstorm begins to dissipate, this occurs when the downdrafts in the cloud begins to dominate over the updraft. Since warm moist air can no longer rise, cloud droplets can no longer form
• Impending signs of thunderstorm

  • System of cumulonimbus clouds: Unequal heating of the Earth's surface causes the upward movement of moist air, forming a tower of cumulonimbus clouds
  • Sky turns dark: The cumulonimbus clouds filled with water droplets serve as a barrier for sunlight. The sky darkens with a greyish tint or may also have hues of green, yellow, or violet
  • Lighting and thunder: Flashes of lightning followed by thunder may be observed. This may occur even before the rain falls
  • Gusts of wind and changes in wind direction: Downburst descend even faster and maybe as strong as a tornado
• Flood


  A high-water stage in which water overflows its natural or artificial banks onto normally dry land, such as a river inundating its floodplain. The effects of floods on human well-being range from unqualified blessings to catastrophes
• Main types of floods


  • Inland flooding
  • Flash floods
  • River flooding
  • Coastal flooding
  • Urban flooding
• Flash flood

  • Caused by heavy rain or the sudden release of water over a short period of time
  • The name "flash" refers to their fast occurrence and also to their raging torrents of water that move with great speed
  • Flash floods are also caused by heavy precipitation in a short period of time, usually less than 6 hours
• Storm surge


  • The irregular sea-level rise during tropical cyclone or "bagyo" occurs
  • When the tropical cyclone reaches the coast, powerful winds force the ocean water over the coastal low-lying areas, which can lead to flooding
• El Niño


  El Niño refers to the large-scale ocean-atmosphere climate interaction linked to a periodic warming in sea surface temperatures across the central and east-central Equatorial Pacific
• La Niña


  • Represent periods of below-average sea surface temperatures across the east-central Equatorial Pacific
  • Global climate La Niña impacts tend to be opposite those of El Niño impacts. In the tropics, ocean temperature variations in La Niña also tend to be opposite those of El Niño
• El Niño effects on health


  • Diseases related to water scarcity or shortage such as diarrhea and skin diseases
  • Red Tide Blooms: Paralytic shellfish poisoning
  • Disorders associated with high temperatures: heat cramps, heat exhaustion, exertional heat injury and heat stroke
• La Niña effects on health

  • Diseases related to contaminated water due to flooding, such as acute gastroenteritis, typhoid fever, cholera and hepatitis A
  • Diseases related to wading in floodwaters contaminated with urine of infected animals, such as leptospirosis
  • Disease brought by mosquitoes, such as dengue and malaria
  • Accidents and injuries such as contusions, lacerations, fractures, electrocution
• La Niña global impacts

  • Stronger winds along the equatorial region, especially in the Pacific
  • Decreased convection in the Pacific leading to a weaker jet stream temperatures are above average in the southeast and below average in the northwest
  • Conditions are more favorable for hurricanes in the Caribbean and central Atlantic area
  • Greater instances of tornados in those states of the US already vulnerable to them
• Weather forecast


  • Done by meteorologist
  • He/she must know about the existing weather conditions over a large area
  • The accuracy of forecast decisions is based on forecasting tools known as the Weather Map
• Weather map


  Displays the air pressure, wind, temperature, and humidity distribution trends at various atmospheric rates
• Types of weather maps


  • Surface map
  • Upper-air map
• Surface map


  Shows air temperature, wind, pressure, and humidity at the Earth's surface
• Upper-air map


  Shows the same weather elements but at various levels in the atmosphere
• Weather forecast


  Done by meteorologist
• Meteorologist


  • Must know about the existing weather conditions over a large area
  • The accuracy of forecast decisions is based on forecasting tools known as the Weather Map
• Two kinds of weather maps


  • Surface Map
  • Basic Weather Map
• Surface Map


  Shows air temperature, dewpoint temperature, air pressure, and wind formation (wind speed and direction)
• Basic Weather Map


  Depicts the distribution patterns of atmospheric pressure, wind, temperature, and humidity at the different levels of the atmosphere
• Steps in making weather forecast


  1. Observation

  2. Collection and transmission of weather data

  3. Plotting of weather data

  4. Analysis of weather maps, satellite, and radar imageries, and other data

  5. Formulation of the forecast
• Observation


  • A meteorologist forecasts weather decision through surface observations at least every three hours over land and sea, and upper air stations at least every twelve hours
  • Weather radars are also used to track the position of the atmosphere within radar range
  • A numerical weather prediction is fed to the computer which analyzes data as programmed and makes a time integration of physical equations
  • Meteorological satellites, geostationary and polar orbiting, take pictures of the cloud imagery of the atmosphere
• Collection and transmission of weather data

  • Condensed into coded figures, symbols and numerals are transmitted via radiophone, teletype, facsimile machine or telephone to designated collection centers for further transmission to the central forecasting station
  • Weather satellite images are transmitted to receiving stations on the ground while radar measurements are transmitted through a local communication network to forecast centers
• Plotting of weather data


  • Observations on land and sea are plotted on charts of surface or mean sea level, which are prepared four times a day
  • Once the coded messages have been received, they are decoded, and each set of observations is plotted over the respective areas or regions in symbols or numbers on weather charts
  • Observations of radiosonde, theodolite, aircraft, and satellite wind are plotted on top-level charts that are prepared twice daily
• Four weather charts

  • Surface (MSL) Chart
  • Upper Air Charts
  • Numerical Weather Prediction Model Output
  • Monitor Weather Charts
• Surface (MSL) Chart


  Data plotted on this weather map are analyzed isobarically. The same atmospheric pressure at different places is interconnected with a line taking into consideration the direction of the winds.
• Upper Air Charts


  Data plotted on this weather map are analyzed using streamlined analysis
• Numerical Weather Prediction Model Output


  Computer-plotted weather maps are analyzed manually so that weather systems like cyclones and anticyclones are located
• Monitor Weather Charts


  Plotted cross-section data, rainfall charts and 24 hours pressure change charts are analyzed to determine wind wave movement, rainfall distribution and atmospheric pressure behavior