Amihan
Amihan is the Filipino term for the northeast monsoon, a cooler, drier wind pattern that typically affects the Philippines from around October to February.
Full entry →Cone of Uncertainty
The cone of uncertainty is the shaded area shown on a forecast track map representing the range of possible paths a tropical cyclone's center could take, based on the historical accuracy of past forecasts.
Full entry →Eye
The eye is the calm, roughly circular center of a typhoon, typically 30 to 65 kilometers wide, where winds are light and skies can be clear.
Full entry →Flash Flood
A flash flood is a sudden, fast-rising flood that develops within minutes to a few hours, usually caused by intense rainfall over a short period.
Full entry →Flood Warning
A flood warning is an official notice indicating that flooding is occurring or is imminent in a specific area, issued by PAGASA or local disaster offices based on river levels or rainfall forecasts.
Full entry →Forecast Track
A forecast track is the projected future path of a tropical cyclone, issued by PAGASA and other agencies and updated with each new bulletin as conditions change.
Full entry →Habagat
Habagat is the Filipino term for the southwest monsoon, a seasonal wind pattern from roughly June to September that brings sustained heavy rainfall to Luzon and the western Visayas.
Full entry →Landfall
Landfall is the point at which a tropical cyclone's center crosses from open water onto land.
Full entry →Low Pressure Area (LPA)
A low pressure area, or LPA, is a region where atmospheric pressure is lower than its surroundings, often the earliest stage PAGASA flags before a system strengthens into a tropical depression.
Full entry →PAGASA
PAGASA, the Philippine Atmospheric, Geophysical and Astronomical Services Administration, is the national agency responsible for weather forecasting, typhoon tracking, and public weather warnings in the Philippines.
Full entry →Rapid Intensification
Rapid intensification is officially defined as an increase in a tropical cyclone's maximum sustained winds of at least 55 km/h within a 24-hour period.
Full entry →Satellite Imagery
Satellite imagery refers to the visible, infrared, and other captured images used to monitor a tropical cyclone's cloud structure, size, and organization from space.
Full entry →Storm Surge
Storm surge is an abnormal rise in sea level caused by a tropical cyclone's winds pushing water toward the coast, capable of flooding low-lying areas far beyond the normal high tide line.
Full entry →Super Typhoon
A super typhoon is PAGASA's classification for a typhoon with maximum sustained winds exceeding 220 km/h.
Full entry →Tropical Cyclone Wind Signal (TCWS)
The Tropical Cyclone Wind Signal, or TCWS, is PAGASA's five-level system indicating expected wind strength and the precautions residents in an affected area should take.
Full entry →Tropical Depression
A tropical depression is a tropical cyclone with maximum sustained winds of 55 km/h or less, the first classification stage under PAGASA's wind signal system.
Full entry →Tropical Storm
A tropical storm has maximum sustained winds between 62 and 88 km/h, strong enough that PAGASA assigns an internationally recognized name.
Full entry →Typhoon
A typhoon is a tropical cyclone with maximum sustained winds of 118 km/h or higher, the term used in the Northwest Pacific for what is called a hurricane in the Atlantic.
Full entry →Update
An update is a newer bulletin or advisory issued as a tropical cyclone's position, intensity, or forecast track changes, replacing the information in the previous release.
Full entry →No terms match your search.
Extratropical Cyclone
An extratropical cyclone is a storm system that draws its energy from temperature contrasts between air masses rather than warm ocean water, unlike a tropical cyclone.
Low Pressure Area (LPA)
A low pressure area, or LPA, is a region where atmospheric pressure is lower than its surroundings, often the earliest stage PAGASA flags before a system strengthens into a tropical depression.
Post-Tropical Cyclone
A post-tropical cyclone is a former tropical cyclone that has lost its tropical characteristics, such as a warm core, but can still produce heavy rain and strong wind.
Remnant Low
A remnant low is what remains of a tropical cyclone after its organized circulation and rain bands have broken down, though the low pressure center may persist.
Severe Tropical Storm
A severe tropical storm has maximum sustained winds between 89 and 117 km/h, one step below typhoon strength.
Super Typhoon
A super typhoon is PAGASA's classification for a typhoon with maximum sustained winds exceeding 220 km/h.
Tropical Cyclone
A tropical cyclone is a rotating low pressure weather system that forms over warm ocean water and draws its energy from heat released as moist air rises and condenses.
Tropical Cyclone Bulletin
A tropical cyclone bulletin is PAGASA's regularly updated advisory covering a storm's position, intensity, forecast track, and wind signals in effect.
Tropical Depression
A tropical depression is a tropical cyclone with maximum sustained winds of 55 km/h or less, the first classification stage under PAGASA's wind signal system.
Tropical Depression Warning
A tropical depression warning is a PAGASA bulletin issued once a system has been upgraded to tropical depression status, outlining expected track and areas at risk.
Tropical Disturbance
A tropical disturbance is an organized area of thunderstorms over tropical waters that has not yet developed the closed, rotating circulation needed to be classified as a tropical cyclone.
Tropical Storm
A tropical storm has maximum sustained winds between 62 and 88 km/h, strong enough that PAGASA assigns an internationally recognized name.
Tropical Wave
A tropical wave is a trough of low pressure moving through the tropics that can seed the thunderstorm activity from which a tropical cyclone eventually forms.
Typhoon
A typhoon is a tropical cyclone with maximum sustained winds of 118 km/h or higher, the term used in the Northwest Pacific for what is called a hurricane in the Atlantic.
Center of Circulation
The center of circulation is the precise point around which a typhoon's winds rotate, tracked by forecasters to plot the storm's position and path.
Central Dense Overcast (CDO)
The central dense overcast, or CDO, is the thick shield of high clouds covering a typhoon's core, visible on satellite imagery as a solid white mass.
Cloud Shield
The cloud shield is the broad canopy of high cirrus clouds that spreads outward from a typhoon's core, often visible on satellite well before the storm's center arrives.
Convective Bands
Convective bands are elongated clusters of thunderstorms within a typhoon's circulation, another term used for the same feature as rainbands.
Cyclonic Circulation
Cyclonic circulation refers to counterclockwise rotating wind flow around a low pressure center in the Northern Hemisphere, the defining motion of a tropical cyclone.
Eye
The eye is the calm, roughly circular center of a typhoon, typically 30 to 65 kilometers wide, where winds are light and skies can be clear.
Eyewall
The eyewall is the ring of towering thunderstorms immediately surrounding the eye, where a typhoon's strongest winds and heaviest rain occur.
Eyewall Replacement Cycle
An eyewall replacement cycle occurs when a second, outer ring of thunderstorms forms around an intense typhoon, gradually chokes off the original eyewall, and takes its place.
Feeder Bands
Feeder bands are outer rainbands that draw warm, moist air into a typhoon's circulation, effectively feeding the storm's core with energy.
Inflow
Inflow is the low-level air spiraling into a typhoon's center, carrying the warm, moist ocean air that fuels the storm.
Inner Core
The inner core is the central region of a typhoon comprising the eye and eyewall, where the most rapid changes in intensity take place.
Outer Core
The outer core is the broader region of a typhoon beyond the eyewall, made up of spiral rainbands and weaker, more diffuse circulation.
Outflow
Outflow is the air that exits a typhoon at high altitude after rising through the storm, spreading outward and away from the center.
Rainbands
Rainbands are the curved bands of thunderstorms that spiral outward from a typhoon's center, producing heavy rain and gusty winds well ahead of the main circulation.
Spiral Rainbands
Spiral rainbands are the distinctive curved bands of thunderstorms visible on satellite imagery that wind inward toward a typhoon's eyewall.
Vortex
A vortex is a mass of spinning air, the general meteorological term for the rotating structure at the heart of a typhoon.
Atmospheric Instability
Atmospheric instability describes conditions where warm air readily rises through the atmosphere, fueling the thunderstorm activity a tropical cyclone needs to organize and grow.
Coriolis Effect
The Coriolis effect is the force caused by Earth's rotation that deflects moving air and gives tropical cyclones their spin, counterclockwise in the Northern Hemisphere.
Dissipation
Dissipation is the breakdown of a tropical cyclone's organized circulation, typically caused by land interaction, cooler water, or increasing wind shear.
Genesis
Genesis is the formal meteorological term for the formation of a tropical cyclone, the point at which a disturbance develops a closed low-level circulation.
Intensification
Intensification is the general process of a tropical cyclone's winds and organization strengthening over time, as opposed to the specific, faster threshold defined by rapid intensification.
Land Interaction
Land interaction refers to the weakening effect land has on a tropical cyclone once it moves over it, cutting off the storm's supply of warm ocean moisture and increasing surface friction.
Low-Level Circulation
Low-level circulation is the rotating wind pattern near the ocean surface that, once it becomes organized and persistent, marks the transition from a disturbance to a tropical depression.
Moist Air
Moist air is air carrying high humidity, providing the water vapor that condenses into the clouds and rainfall powering a tropical cyclone.
Ocean Heat Content
Ocean heat content measures the total heat energy stored in the upper ocean, a more complete indicator of a storm's potential fuel supply than surface temperature alone.
Rapid Intensification
Rapid intensification is officially defined as an increase in a tropical cyclone's maximum sustained winds of at least 55 km/h within a 24-hour period.
Rapid Weakening
Rapid weakening is a sharp drop in a tropical cyclone's maximum sustained winds over a short period, often caused by land interaction, dry air intrusion, or increased wind shear.
Sea Surface Temperature
Sea surface temperature is the temperature of the ocean's uppermost layer, the single most important factor in whether a tropical disturbance can develop into a cyclone.
Vertical Wind Shear
Vertical wind shear is the change in wind speed or direction with height, and high shear is one of the main factors that prevents a tropical cyclone from forming or intensifying.
Warm Ocean Water
Warm ocean water is sea surface temperature of roughly 26.5 degrees Celsius or higher, the minimum threshold typically needed for a tropical cyclone to form and intensify.
Cone of Uncertainty
The cone of uncertainty is the shaded area shown on a forecast track map representing the range of possible paths a tropical cyclone's center could take, based on the historical accuracy of past forecasts.
Eastward Movement
Eastward movement describes a tropical cyclone tracking from west to east, an uncommon direction usually associated with a weakening or dissipating system caught in unusual steering flow.
Forecast Track
A forecast track is the projected future path of a tropical cyclone, issued by PAGASA and other agencies and updated with each new bulletin as conditions change.
Forward Speed
Forward speed is how fast a tropical cyclone's center is moving along its track, distinct from its wind speed, which measures how strong the winds are rotating around that center.
Landfall
Landfall is the point at which a tropical cyclone's center crosses from open water onto land.
Northeast Track
A northeast track describes a tropical cyclone that has recurved, shifting from a westward or northwestward path toward the northeast, typically after clearing the Philippines or Taiwan.
Northwest Track
A northwest track is a common path for Northwest Pacific tropical cyclones, curving from an initial westward motion toward the northwest as they near or cross the Philippines.
Recurvature
Recurvature is a tropical cyclone's shift from a westward track to a northward or northeastward one, usually caused by a break or weakening in the steering ridge of high pressure.
Second Landfall
A second landfall occurs when a tropical cyclone crosses back over water after an initial landfall and then makes landfall again on a different part of the coast or a different island.
Stationary Cyclone
A stationary cyclone is a tropical cyclone whose forward speed has slowed to near zero, often due to weak or conflicting steering flow.
Steering Flow
Steering flow is the broader pattern of winds in the atmosphere that pushes a tropical cyclone along its path, much like a leaf carried by a current.
Track
A track is the path a tropical cyclone follows over time, plotted from its center of circulation at each successive observation.
Westward Movement
Westward movement describes a tropical cyclone tracking from east to west, the typical direction for storms in the early stages of crossing the Philippine Area of Responsibility, driven by the prevailing easterlies.
Destructive Wind
Destructive wind refers to wind speeds capable of causing significant damage to structures, trees, and infrastructure, typically associated with typhoon and super typhoon strength systems.
Gale
A gale is sustained wind of 39 to 61 knots, roughly 63 to 88 km/h, strong enough to prompt gale warnings for coastal and marine areas.
Gust
A gust is a brief spike in wind speed above the sustained wind, typically lasting only a few seconds, but capable of causing damage that sustained winds alone would not.
Maximum Sustained Winds
Maximum sustained winds is the highest sustained wind speed found anywhere within a tropical cyclone's circulation, usually located in the eyewall, and the figure used to determine its official classification.
Strong Breeze
A strong breeze is a wind classification on the Beaufort scale, roughly 39 to 49 km/h, strong enough to make walking difficult and cause small branches to move.
Sustained Wind
Sustained wind is wind speed averaged over a set period, typically one or ten minutes depending on the agency, and the measurement used to classify a tropical cyclone's category.
Violent Wind
Violent wind describes wind strong enough to cause widespread structural damage, generally corresponding to the higher PAGASA wind signal levels.
Wind Direction
Wind direction indicates where the wind is blowing from, described using compass points, and shifts predictably as a tropical cyclone's circulation passes over a fixed location.
Wind Speed
Wind speed is the rate at which air moves, typically measured in kilometers per hour, and the basis for both PAGASA's wind signal levels and a storm's overall classification.
Continuous Rain
Continuous rain is rainfall that persists steadily over an extended period without significant breaks, a pattern that raises flood risk even at moderate rain rates due to accumulated volume.
Heavy Rainfall
Heavy rainfall generally refers to rain falling at 7.5 mm per hour or more, the threshold where PAGASA begins issuing color-coded rainfall warnings.
Intense Rainfall
Intense rainfall describes rain falling at a rate significant enough to cause rapid runoff and flooding, generally in the range covered by PAGASA's orange rainfall warning.
Localized Rainfall
Localized rainfall describes rain concentrated in a specific area rather than spread evenly across a region, often tied to individual rainbands or terrain effects.
Rain Rate
Rain rate is the intensity of rainfall measured in millimeters per hour, the figure PAGASA uses to determine which color-coded rainfall warning to issue.
Rainfall
Rainfall is the general term for precipitation falling as rain, measured in millimeters and tracked both as a rate per hour and as total accumulation over a storm's passage.
Rainfall Accumulation
Rainfall accumulation is the total amount of rain that has fallen over a set period, such as 24 hours, distinct from rain rate, which measures intensity at a single point in time.
Rainfall Advisory
A rainfall advisory is a PAGASA notice highlighting expected rain intensity and potential flooding impact, issued using the yellow, orange, and red color-coded warning levels.
Torrential Rain
Torrential rain is very heavy rainfall, generally exceeding 30 mm per hour, corresponding to PAGASA's red rainfall warning and capable of causing severe flooding even in areas not typically prone to it.
Coastal Flooding
Coastal flooding is flooding driven by seawater pushing onto land, most commonly caused by storm surge during a typhoon's passage near or over the coastline.
Flash Flood
A flash flood is a sudden, fast-rising flood that develops within minutes to a few hours, usually caused by intense rainfall over a short period.
Flood Advisory
A flood advisory is a lower-level notice than a flood warning, indicating that flooding is possible but not yet occurring or imminent.
Flood Depth
Flood depth is the measured or estimated height of floodwater above ground level, used to assess severity and guide evacuation decisions.
Flood Risk
Flood risk describes the likelihood and potential severity of flooding in a given area, based on factors like elevation, proximity to rivers or coastline, and historical flooding patterns.
Flood Warning
A flood warning is an official notice indicating that flooding is occurring or is imminent in a specific area, issued by PAGASA or local disaster offices based on river levels or rainfall forecasts.
Floodplain
A floodplain is the low-lying land bordering a river that is naturally prone to flooding when the river exceeds its capacity.
Inundation
Inundation is the covering of normally dry land with water, the general term used for flooding from any source, whether river, rain, or storm surge.
River Flood
A river flood occurs when sustained or heavy rainfall causes a river to exceed its banks, typically developing more slowly than a flash flood but affecting a wider area for a longer duration.
Urban Flood
Urban flooding occurs when rainfall overwhelms a city's drainage system, causing water to pool on streets and low-lying areas even without a nearby river overflowing.
Coastal Erosion
Coastal erosion is the wearing away of shoreline by waves and storm surge, which can permanently reshape a coastline after a severe typhoon.
Coastal Inundation
Coastal inundation is the flooding of land along the shoreline by seawater, most often caused by storm surge during a typhoon's approach or landfall.
High Tide
High tide is the point in the daily tidal cycle when sea level reaches its highest, and storm surge coinciding with high tide produces the most severe coastal flooding.
Low Tide
Low tide is the point in the daily tidal cycle when sea level reaches its lowest, offering somewhat reduced coastal flood risk if storm surge arrives at this point in the cycle.
Phenomenal Seas
Phenomenal seas describes wave heights exceeding 14 meters, the most extreme category on the marine sea state scale, occurring only in the most intense typhoons over open water.
Rough Seas
Rough seas describes wave heights of roughly 2.5 to 4 meters, conditions under which PAGASA advises small boats and fishing vessels to remain in port.
Storm Surge
Storm surge is an abnormal rise in sea level caused by a tropical cyclone's winds pushing water toward the coast, capable of flooding low-lying areas far beyond the normal high tide line.
Storm Tide
Storm tide is the combined water level from storm surge plus the normal astronomical tide, and the figure that determines actual flood height at the coast.
Swell
Swell is a series of ocean waves generated by a distant storm system that travels outward and can reach coastlines well before the storm itself, or even if the storm never makes landfall nearby.
Very Rough Seas
Very rough seas describes wave heights of roughly 4 to 6 meters, hazardous conditions under which all sea travel is generally advised against.
Wave Height
Wave height is the vertical distance between a wave's crest and trough, a key figure in PAGASA's marine advisories for fishing and small vessel safety.
Wave Setup
Wave setup is the additional rise in nearshore water level caused by breaking waves piling up against the coast, a contributing factor to total storm surge height alongside wind-driven water.
Gale Warning
A gale warning is issued for coastal and marine areas when winds of 39 to 61 knots are expected, advising against sea travel for most vessels.
Heavy Rainfall Warning
A heavy rainfall warning is PAGASA's color-coded alert for expected rain accumulation, issued separately from wind signals since heavy rain can occur without strong winds.
Hydrological Forecast
A hydrological forecast projects river and reservoir water levels, used to anticipate flooding downstream of dams and major waterways during heavy rain events.
Orange Rainfall Warning
An orange rainfall warning signals 15 to 30 mm of rain per hour expected to continue for two or more hours, with flooding likely in many areas.
PAGASA
PAGASA, the Philippine Atmospheric, Geophysical and Astronomical Services Administration, is the national agency responsible for weather forecasting, typhoon tracking, and public weather warnings in the Philippines.
Red Rainfall Warning
A red rainfall warning signals over 30 mm of rain per hour expected to continue for two or more hours, PAGASA's highest rainfall alert, with severe flooding expected even in areas not normally prone to it.
TCWS No. 1
TCWS No. 1 is raised when winds of 30 to 60 km/h are expected within 36 hours, PAGASA's lowest wind signal level.
TCWS No. 2
TCWS No. 2 is raised when winds of 61 to 120 km/h are expected within 24 hours, prompting the suspension of classes in affected areas.
TCWS No. 3
TCWS No. 3 is raised when winds of 121 to 170 km/h are expected within 18 hours, typically prompting preemptive evacuation in coastal and landslide-prone areas.
TCWS No. 4
TCWS No. 4 is raised when winds of 171 to 220 km/h are expected within 12 hours, indicating a very high risk of damage to structures.
TCWS No. 5
TCWS No. 5 is PAGASA's highest wind signal, raised when winds exceeding 220 km/h are expected within 12 hours, associated with catastrophic, widespread damage.
Thunderstorm Advisory
A thunderstorm advisory is issued by PAGASA when isolated to scattered thunderstorms are expected to affect an area within the next two hours.
Tropical Cyclone Wind Signal (TCWS)
The Tropical Cyclone Wind Signal, or TCWS, is PAGASA's five-level system indicating expected wind strength and the precautions residents in an affected area should take.
Weather Advisory
A weather advisory is a shorter-form PAGASA notice highlighting a specific expected hazard, such as localized thunderstorms or gusty winds, without the full detail of a bulletin.
Weather Bulletin
A weather bulletin is PAGASA's general-purpose update on current and forecast weather conditions, distinct from a tropical cyclone bulletin issued specifically for an active storm.
Yellow Rainfall Warning
A yellow rainfall warning signals 7.5 to 15 mm of rain per hour expected to continue for two or more hours, enough to flood low-lying, flood-prone areas.
Japan Meteorological Agency (JMA)
The Japan Meteorological Agency, or JMA, is the Regional Specialized Meteorological Center officially responsible for naming and issuing warnings on tropical cyclones across the Northwest Pacific, including those affecting the Philippines.
Joint Typhoon Warning Center (JTWC)
The Joint Typhoon Warning Center, or JTWC, is a US Navy and Air Force agency that issues tropical cyclone warnings and forecasts for the Pacific and Indian Oceans, widely used alongside PAGASA and JMA data.
Regional Specialized Meteorological Center (RSMC)
A Regional Specialized Meteorological Center, or RSMC, is a designation given by the WMO to a national agency responsible for official tropical cyclone forecasting and naming within a defined ocean basin, a role JMA holds for the Northwest Pacific.
World Meteorological Organization (WMO)
The World Meteorological Organization, or WMO, is the United Nations agency that coordinates international weather forecasting standards, including the regional naming systems used for tropical cyclones.
Amihan
Amihan is the Filipino term for the northeast monsoon, a cooler, drier wind pattern that typically affects the Philippines from around October to February.
Easterlies
Easterlies are prevailing winds that blow from east to west across the tropics, the general wind pattern that steers most tropical cyclones toward the Philippines from the Pacific.
Frontal System
A frontal system is a boundary between two air masses of different temperature and humidity, a feature more common in temperate latitudes but one that can occasionally influence weather over the northern Philippines.
Habagat
Habagat is the Filipino term for the southwest monsoon, a seasonal wind pattern from roughly June to September that brings sustained heavy rainfall to Luzon and the western Visayas.
High Pressure Area
A high pressure area is a region where atmospheric pressure is higher than its surroundings, generally associated with fair, stable weather and the opposite of the low pressure areas that spawn tropical cyclones.
Intertropical Convergence Zone (ITCZ)
The Intertropical Convergence Zone, or ITCZ, is a band near the equator where trade winds from both hemispheres converge, often triggering the thunderstorm clusters that can develop into tropical cyclones.
Northeast Monsoon
The northeast monsoon is the seasonal wind system, known locally as amihan, that brings cooler and generally drier conditions to the Philippines from around October to February.
Ridge
A ridge is an elongated extension of high pressure, often acting as a steering influence that pushes a nearby tropical cyclone along a particular track.
Ridge of High Pressure
A ridge of high pressure is an elongated area of relatively higher atmospheric pressure that can steer or block a tropical cyclone's path, sometimes causing a storm to stall or change direction.
Shear Line
A shear line is a boundary where winds from different directions meet, often producing a band of clouds and rain that can bring flooding independent of any tropical cyclone.
Southwest Monsoon
The southwest monsoon is the seasonal wind system, known locally as habagat, that brings sustained heavy rainfall to the western Philippines from around June to September.
Trough
A trough is an elongated extension of low pressure, often associated with cloudiness and rain, and the opposite counterpart to a ridge.
Advisory
An advisory is a general term for an official weather notice highlighting an expected hazard, ranging from a specific tropical cyclone advisory to a shorter-form warning about localized conditions.
Bulletin
A bulletin is the formal, structured document PAGASA issues covering a tropical cyclone's current position, strength, forecast track, and wind signals in effect for specific areas.
Doppler Radar
Doppler radar is an advanced form of weather radar that also measures wind velocity, allowing forecasters to detect rotation and intensity changes within a storm's rainbands as it approaches.
Ensemble Forecast
An ensemble forecast runs a weather model multiple times with slightly different starting conditions, producing a range of possible outcomes used to gauge forecast confidence.
Forecast
A forecast is a prediction of future weather conditions based on current atmospheric data, computer models, and forecaster analysis.
Forecast Confidence
Forecast confidence reflects how much agreement exists across different weather models and ensemble members regarding a storm's future track and intensity.
Numerical Weather Prediction
Numerical weather prediction is the general method of using mathematical models of the atmosphere, run on supercomputers, to generate forecasts, the underlying approach behind every modern weather model.
Probability Forecast
A probability forecast expresses the likelihood of a specific weather outcome, such as the percent chance a given area will experience damaging winds from an approaching typhoon.
Radar
Radar detects precipitation and its movement by sending out radio waves and measuring what bounces back, giving forecasters detailed, near real-time views of rainfall intensity once a storm is close enough to land-based radar coverage.
Satellite Imagery
Satellite imagery refers to the visible, infrared, and other captured images used to monitor a tropical cyclone's cloud structure, size, and organization from space.
Update
An update is a newer bulletin or advisory issued as a tropical cyclone's position, intensity, or forecast track changes, replacing the information in the previous release.
Weather Model
A weather model is a computer simulation of the atmosphere used to project how current conditions, including a tropical cyclone's position and intensity, will evolve over time.
Weather Satellite
A weather satellite is an orbiting instrument that captures continuous imagery of cloud patterns, used to track a tropical cyclone's position, structure, and intensity, especially over open ocean where no other data exists.
Air Pressure
Air pressure is another term for atmospheric pressure, the force exerted by the weight of the atmosphere at a given location.
Atmospheric Pressure
Atmospheric pressure is the weight of the air pressing down on a given point, and a tropical cyclone's central pressure is one of the key figures used to estimate its intensity.
Barometric Pressure
Barometric pressure is atmospheric pressure as measured by a barometer, the standard instrument used to track pressure changes as a storm approaches.
Dew Point
Dew point is the temperature at which air becomes saturated with moisture and condensation begins to form, a more consistent measure of humidity than relative humidity alone.
Hectopascal (hPa)
The hectopascal, or hPa, is the standard unit meteorologists use to measure atmospheric pressure, with a typical fair-weather reading around 1013 hPa at sea level.
Humidity
Humidity is the amount of water vapor present in the air, a key ingredient that fuels the thunderstorm activity within a tropical cyclone.
Millibar
A millibar is a unit of atmospheric pressure, numerically equal to a hectopascal, historically used before hPa became the standard meteorological unit.
Relative Humidity
Relative humidity is the amount of water vapor in the air expressed as a percentage of the maximum the air could hold at that temperature.
Temperature
Temperature measures how warm or cool the air is, and sea surface temperature specifically is one of the main factors determining whether a tropical cyclone can form or intensify.
Wind Chill
Wind chill is the perceived drop in temperature caused by wind increasing the rate of heat loss from exposed skin, a measurement more relevant to temperate climates than the tropical Philippines.
Disaster Response
Disaster response is the overall coordinated effort by government agencies, local units, and humanitarian organizations to address the immediate needs of a community affected by a typhoon.
Disaster Risk Reduction
Disaster risk reduction is the broad practice of minimizing the impact of hazards like typhoons through preparedness, mitigation, and planning, rather than only responding after a disaster occurs.
Emergency Kit
An emergency kit is a prepared set of essential supplies, such as water, food, flashlights, and first aid items, kept ready in case a typhoon requires evacuation or extended power outage.
Emergency Shelter
Emergency shelter refers to temporary housing provided to displaced residents after a typhoon has damaged or destroyed their homes.
Evacuation
Evacuation is the organized movement of people away from an area expected to be affected by a typhoon's hazards, whether wind, flooding, storm surge, or landslide risk.
Evacuation Center
An evacuation center is a designated public facility, often a school or barangay hall, set up to temporarily shelter residents displaced ahead of or during a typhoon.
Go Bag
A go bag is a portable emergency kit packed in advance so a household can evacuate quickly with essential supplies, documents, and medication in a single grab.
Incident Command System
The Incident Command System is a standardized management structure used to coordinate personnel, resources, and communication during a disaster response, adopted by Philippine disaster agencies for large-scale typhoon operations.
Mitigation
Mitigation refers to long-term measures that reduce a community's vulnerability to future disasters, such as building sea walls, enforcing flood-resilient construction codes, or reforesting watersheds.
Preemptive Evacuation
Preemptive evacuation is the movement of residents out of high-risk areas before a typhoon arrives, rather than waiting until flooding, landslides, or storm surge are already underway.
Preparedness
Preparedness covers the actions taken before a typhoon strikes, such as stocking emergency supplies, securing property, and knowing evacuation routes, to reduce harm once the storm arrives.
Recovery
Recovery is the phase following a typhoon focused on restoring homes, infrastructure, and livelihoods, often extending months or years after the storm itself has passed.
Relief Operations
Relief operations involve distributing food, water, medical care, and other essential supplies to communities affected by a typhoon, typically coordinated by local government and the DSWD.
Rescue Operations
Rescue operations are the coordinated efforts to locate and safely remove people stranded or trapped by flooding, landslides, or storm damage during a typhoon.
Response
Response is the phase of disaster management focused on immediate actions during and right after a typhoon, including rescue, evacuation, and emergency relief.
Barangay DRRM
Barangay DRRM refers to the disaster risk reduction and management responsibilities held at the barangay level, the smallest unit of local government and often the first point of coordination during a typhoon.
CDRRMO
The CDRRMO, or City Disaster Risk Reduction and Management Office, is the local government unit responsible for disaster preparedness and response at the city level.
MDRRMO
The MDRRMO, or Municipal Disaster Risk Reduction and Management Office, is the local government unit responsible for disaster preparedness and response at the municipal level.
NDRRMC
The NDRRMC, or National Disaster Risk Reduction and Management Council, is the top-level government body that coordinates disaster preparedness, response, and recovery across the Philippines.
OCD
The OCD, or Office of Civil Defense, serves as the operating arm of the NDRRMC, implementing national disaster policy and coordinating with regional and local disaster offices.
State of Calamity
A state of calamity is an official declaration by a local or national government following a disaster, unlocking emergency funds and enabling price controls on essential goods in the affected area.
Suspension of Classes
Suspension of classes is a local government or school-level order canceling in-person classes, typically issued once a wind signal is raised or heavy flooding is expected in the area.
Suspension of Work
Suspension of work is a local government order halting work in government offices and, in some cases, the private sector, issued under similar conditions to a class suspension during a typhoon.
Coastal Waters
Coastal waters are the sea areas close to shore, generally more sheltered than open or offshore waters but still subject to PAGASA's marine advisories during a typhoon.
Fishing Advisory
A fishing advisory warns fishing operators of unsafe sea conditions, often tied to a gale warning or rough sea state during a nearby tropical cyclone.
Offshore Waters
Offshore waters are sea areas beyond the coastal zone but not yet in the open sea, typically experiencing rougher conditions than coastal waters during a passing tropical cyclone.
Open Sea
Open sea refers to waters beyond the sheltered coastal zone, where wave heights and wind conditions tend to be more severe during a typhoon than in coastal waters.
Small Craft Advisory
A small craft advisory is a PAGASA notice warning small fishing boats and recreational vessels to avoid sailing due to hazardous wind or wave conditions.
Swell Direction
Swell direction indicates where incoming ocean swell is traveling from, information used by mariners and coastal communities to anticipate wave impact even before a storm arrives.
Wave Period
Wave period is the time between successive wave crests, a figure used alongside wave height to assess how hazardous sea conditions are for vessels.
Catch Basin
A catch basin is a drainage structure designed to collect surface runoff and channel it away from roads and low-lying areas, reducing localized flooding during heavy rain.
Dam Spillway
A dam spillway is a structure that releases excess water from a reservoir to prevent overtopping, and spillway releases during heavy typhoon rainfall are a major contributor to downstream flooding.
Reservoir
A reservoir is a large artificial or natural body of water used to store water for supply, irrigation, or flood control, requiring careful management during heavy typhoon rainfall.
River Basin
A river basin is the larger geographic area drained by a river and all its tributaries, encompassing multiple watersheds.
River Level
River level specifically refers to the water level of a river, monitored at gauging stations and compared against alert, alarm, and critical thresholds during heavy rainfall.
Streamflow
Streamflow is the volume of water moving through a river or stream channel over time, used alongside water level to assess flood risk and dam release planning.
Water Level
Water level is the height of water in a river, reservoir, or other body, tracked continuously to determine when flood warnings or evacuation orders should be issued.
Watershed
A watershed is the area of land where all rainfall and runoff drain toward a common river, lake, or outlet, the basic unit used to track flood risk from heavy typhoon rainfall.
Climate Change
Climate change refers to long-term shifts in global weather patterns, linked by researchers to trends such as rising sea levels that worsen storm surge impact and warmer oceans that can fuel more intense typhoons.
Dry Season
The dry season in the Philippines runs roughly from December to May, when tropical cyclone activity and overall rainfall are typically at their lowest.
ENSO
ENSO, or El Niño Southern Oscillation, is the broader climate cycle encompassing both El Niño and La Niña phases, tracked by PAGASA to inform seasonal typhoon and rainfall outlooks.
El Niño
El Niño is a climate pattern marked by warmer than normal sea surface temperatures in the central and eastern Pacific, generally associated with fewer tropical cyclones affecting the Philippines and a higher risk of drought.
La Niña
La Niña is a climate pattern marked by cooler than normal sea surface temperatures in the central and eastern Pacific, generally associated with more tropical cyclone activity and higher rainfall in the Philippines.
Seasonal Forecast
A seasonal forecast is a long-range outlook, typically issued by PAGASA at the start of the year, projecting how many tropical cyclones are expected to affect the Philippines in the months ahead.
Wet Season
The wet season in the Philippines runs roughly from June to November, overlapping closely with the peak of typhoon season and the southwest monsoon.
Crop Damage
Crop damage refers to agricultural losses caused by a typhoon's wind, flooding, or saltwater intrusion, a major economic impact in farming provinces across the Philippines.
Debris Flow
A debris flow is a fast-moving mixture of water, mud, and rock that rushes down a slope or channel, a more destructive variant of a landslide often triggered by intense rainfall.
Fallen Trees
Fallen trees are a common source of damage during a typhoon, blocking roads, damaging structures, and downing power lines even at moderate wind signal levels.
Flood Damage
Flood damage refers to harm caused by floodwater, including structural damage, contamination, and loss of belongings, and is often assessed separately from wind damage in disaster reports.
Infrastructure Damage
Infrastructure damage covers harm to roads, bridges, power lines, and public facilities caused by a typhoon, often the slowest category of damage to fully repair after a major storm.
Landslide
A landslide is the sudden downward movement of soil and rock on a slope, commonly triggered by saturated ground after prolonged or intense typhoon rainfall.
Power Outage
A power outage is a loss of electricity, commonly caused by fallen trees, damaged power lines, or precautionary shutdowns during a typhoon's passage.
Storm Damage Assessment
Storm damage assessment is the post-typhoon process of surveying and documenting harm to homes, infrastructure, and agriculture, used to guide relief distribution and calamity fund allocation.
Wind Damage
Wind damage refers to structural harm caused directly by a typhoon's winds, ranging from roof and signage damage at lower wind signals to widespread building collapse under super typhoon conditions.
Auxiliary Names
Auxiliary names are a backup list PAGASA uses when more tropical cyclones form in a single year than the regular annual list of names can cover.
International Naming System
The international naming system, maintained by the WMO through JMA, assigns names to tropical cyclones in the Northwest Pacific from a rotating list contributed by member countries across the region.
PAGASA Naming System
The PAGASA naming system assigns a local Filipino name to any tropical cyclone that enters the Philippine Area of Responsibility, separate from the international name the same storm may carry.
Retired Typhoon Names
Retired typhoon names are names permanently removed from PAGASA's or the international naming list following a storm so catastrophic or deadly that reusing the name is considered inappropriate.
Tropical Cyclone Name List
A tropical cyclone name list is the pre-assigned, rotating set of names PAGASA or JMA cycles through each year to identify new storms as they form.
Average Annual Typhoons
On average, roughly 19 to 20 tropical cyclones enter the Philippine Area of Responsibility each year, with about 9 making landfall or crossing the archipelago.
Costliest Typhoon
The costliest typhoon in Philippine history is Haiyan (Yolanda), with total damages estimated at roughly PHP 95.48 billion.
Deadliest Typhoon
The deadliest typhoon in Philippine recorded history is Haiyan (Yolanda), which killed more than 6,300 people as it crossed the Visayas in November 2013.
Earliest Typhoon
The earliest typhoon of a given year refers to the first named tropical cyclone to affect the Philippines, occasionally forming as early as January in years with active early-season conditions.
Latest Typhoon
The latest typhoon of a given year refers to the final named tropical cyclone to affect the Philippines, sometimes forming as late as December during an extended season.
Peak Typhoon Season
Peak typhoon season in the Philippines runs roughly from July through October, when the majority of the country's annual tropical cyclones typically form or make landfall.
Strongest Typhoon
The strongest typhoon to make landfall in the Philippines, and worldwide, on record is Goni (Rolly), which struck Catanduanes in November 2020 with 1-minute sustained winds of 315 km/h.
About This Section
The Philippine Area of Responsibility sees an average of roughly 20 tropical cyclones a year, and the terminology used to describe them spans meteorology, PAGASA's own classification system, and disaster response. This glossary keeps all of it in one place.
Each entry links back to the province pages and PAGASA wind signal reference on azifind.com, so a term like storm surge connects directly to the coastal provinces where it carries the most risk.
Definitions on this page are written independently for azifind.com, informed by PAGASA, the World Bank/GFDRR catastrophe risk data used across our province pages, and AIR Worldwide. About azifind.com →