Hydrometeorological Hazards

• Hydrometeorological hazards are natural processes or phenomena of atmospheric, hydrologic, or oceanographic nature.
• Recognizing signs of impending hydrometeorological hazards, interpreting hazard maps, and using available monitoring tools are essential learning competencies.

Review: Hazard Map

• Hazard maps include a title, location, susceptibility, and color key to provide crucial information.

Hydrometeorological Hazards

• Atmospheric + Hydrological make for hydrometeorological hazards.
• Examples include:
• Typhoon
• Flood
• Thunderstorm
• Storm surge
• El Niño
• La Niña

Typhoon

• A typhoon involves a violent tropical cyclone forming over warm waters north of the equator in the Western Pacific Ocean.
• A low-pressure area has lower atmospheric pressure, cloudiness, and rain with winds below 30 km/h and forms due to warm, rising air over oceans.
• A tropical depression is the weakest stage of a tropical cyclone, with organized circulation and stronger winds (30-61 km/h).

Hurricane vs Typhoon vs Cyclone

• Hurricane, typhoon, and cyclone are the essentially the same weather phenomenon that depends on where the storm forms and happens
• Hurricane = Northeast Pacific and Atlantic Ocean
• Typhoon = Northwest Pacific Ocean
• Cyclone = South Pacific and Indian Ocean

Hazards Associated with Tropical Cyclones:

• Floods
• Strong Winds
• Storm Surge
• Landslides

Tropical Cyclone Classification:

• Tropical Depression: Maximum sustained winds up to 61 kilometers per hour (kph) or less than 33 nautical miles per hour (knots)
• Tropical Storm: Maximum wind speed of 62 to 88 kph or 34 - 47 knots
• Severe Tropical Storm: Maximum wind speed of 89-117 kph or 48-63 knots
• Typhoon: Maximum wind speed of 118-220 kph or 64-120 knots
• Super Typhoon: Maximum wind speed exceeding 220 kph or more than 120 knots

Tropical Cyclone Wind Signals (TCWS)

• TCWS #1: Winds of 30-60 km/h expected within 36 hours.
• TCWS #2: Winds of 61-120 km/h expected within 24 hours.
• TCWS #3: Winds of 121-170 km/h expected within 18 hours.
• TCWS #4: Winds of 171-220 km/h expected within 12 hours.
• TCWS #5: Winds exceeding 220 km/h expected within 12 hours.

Rainfall Warning System

• Advisory (Yellow): Flooding is possible in low-lying areas.
• Alert (Orange): Flooding is threatening with possible landslides.
• Emergency (Red): Severe flooding is expected; roads are not passable, and there is a higher chance of landslides.

Impending Signs of a Typhoon

• Increased ocean swell
• Changes in clouds
• Barometric pressure drop
• Abrupt changes in wind speed

Thunderstorm

• A small-scale storm accompanied by lightning and thunder.

Impending Signs of a Thunderstorm

• System of cumulonimbus clouds due to Earth's surface's unequal heating
• The sky turns dark
• Lightning and thunder
• Gusts of wind and change in wind direction

Storm Surge

• A rapid rise of seawater above normal sea level on the coast, generated by strong winds brought about by typhoons and thunderstorms.

Flood Types

• Flood: When land areas normally not covered with water become submerged, often after heavy/continuous rainfall.
• Flash Flood: Is characterized by a raging current due to heavy rainfall.
• Inland flooding: Flooding that occurs in inland areas, hundreds of miles from the coast.
• Flash floods: Caused by heavy rain or sudden water release within a short period and moves with great speed.
• River flooding: rising water levels in rivers, lakes, and streams that overflow onto the surrounding land.
• Coastal flooding: Inundation of land areas along the coast by seawater
• Urban flooding: Lack of drainage in an urban area

Impending Signs of a Flash Flood

• Typhoon or thunderstorm occurrence
• Water collecting in puddles and rapidly rising
• Muddy water
• Roaring sound from upstream
• Floating debris in water

El Niño and La Niña

• El Niño means "The Little Boy" or "Christ Child" in Spanish and is characterized by warmer-than-average sea surface temperatures in the central and east-central Equatorial Pacific.
• El Niño leads to drier and warmer conditions than normal in the Philippines.
• Reduced rainfall, drought conditions, water shortages, agricultural losses, and increased risk of wildfires are key features of El Niño in the Philippines
• La Niña means "The Little Girl" in Spanish, representing below-average sea surface temperatures.
• La Niña often brings increased rainfall and above-average precipitation, leading to floods and landslides in the Philippines.
• El Nino is the abnormal heating of earth's ocean surface in the Pacific
• La Nina is the abnormal cooling
• Key strategies to mitigate the effects of these climate phenomena include water management, agricultural practices, and public awareness.

Tools for Monitoring Hydrometeorological Hazards

• Includes tools such as barographs, thermographs, clinometers, ceiling balloons, theodolites, radiosondes, rawinsondes, weather surveillance radar, Doppler radar, and weather satellites.
• The Philippine Atmospheric, Geophysical, and Astronomical Services Administration (PAGASA) is responsible for monitoring and issuing typhoon warnings.
• Forecasters are able to use weather maps to forecast and determine the surface map and upper air maps