GUIDE MAP

Hurricanes, Tropical Cyclones and Typhoons

Early Warning levels

Tropical cyclones

Typhoons

Hurricanes

Hurricanes

Hurricanes form in low pressure systems over the Atlantic and are classified on a scale system from 71 mph winds and above.Click on the map to explore different alert levels around the America's, or on the buttons below to learn more:

HOME

• 1 represents possible minor damge
• 5 represents catastophic building failures expected

The US National Hurricane Centre uses the Saffir-Simpson Wind Scale for alert levels. Based on the storm's maximum sustained windspeed.

United STATES

Hurricanes

Caribbean

Caribbean countries have made signifcant progress in co-operatively implimenting and strengthing Hurricane forecasting and early warning. Most nations have adopted a 4 tier system between tropical storms and hurricanes, watch and warning.

Hurricanes

• Green: Watch
• Yellow: Advisory
• Orange: Alert
• Red: Protection and shelter

COLOMBIA

Colombia's National Unit for Disaster Risk Management (UNGRD) and Institute of Hydrology, Meteorology and Environmental Studies (IDEAM) operate a tiered alert system:

Hurricanes

Tropical cyclones that form in the North Pacific Basin are typically called Typhoons. With winds of above ~120km/h.There are regional forecast centres in Japan, Hawaii, the Philippines and Hong Kong.

Typhoons

HOME

• White: Tropical cyclones may pose a risk within the next 48 hours
• Blue: Cyclones pose a risk within 24 hours, with gusts above levels 6
• Yellow: Cyclones pose a risk within 24 hours, with gusts above levels 8
• Orange: Cyclones pose a risk within 24 hours, with gusts above levels 10
• Red: Cyclones pose a risk within 6 hours, with average wind power above level 12

Chinese provinces use a range of early warning alert levels for Typhoons. The five levels shown are from Guangdong; Zhuhai use a variation; wheras Shenzen, Hong Kong and other regions use slightly different symbols.

CHINA

Typhoons

The Japan Meteorological Agency and local authorities issue alerts to multiple hazards especially typhoons. The simple system is designed to speed up evacuations as much as possible.

Japan

Typhoons

In 2023 Vietnam's Meteorological and Hydrological Administration launched an EWS, including a community based element. Text message alerts are also being trialed. While there are no indivual levels of warning as of yet, the system has a large focus on community based approaches (see the links below):

Vietnam

Typhoons

• Signal 1 (Blue): Winds less than 61km/h expected within 36 hours 30
• Signal 2 (Yellow): 88km/h or less in 24 hours
• Signal 3 (Orange): 117km/h or less in 18 hours
• Signal 4 (Red): 184km/h or less in 12 hours
• Signal 5 (Purple): 185km/h or more in 12 hours

The Philippines Atmospheric, Geophysical and Astronomical Services Administration, operates a sophisticated cyclone EWS with clearly defined communication procedures.

Philippines

Typhoons

Tropical cyclones

home

Tropical cyclones form in the Indian Ocean and the South Pacific. 80-90+ Tropical Cyclones form each year. learn more below:

• Advice: No immediate threat, be aware
• Watch & Act: Possible threat to lives and homes, take protective action
• Emergency Warning: Threat to life and homes, take immediate action

Australia

Ahead of the Nov 2024 Cyclone season, Australia altered their cyclone ealry wanring levels in line with all other hazard warnings - removing the all clear signal.

CYCLONES

India's Meterology Department operates a cyclone EWS on a time based protocol:

india

• Pre-cyclone (Yellow): 72 hour warning in advance of landfall.
• Cyclone Alert (Orange): 48 and then 24 hours in advance including location, intensity and track.
• Post Landfall Outlook: 12 hours in advance of landfall, gives likely impacts and movement post landfall

CYCLONES

Sri Lanka

Sri Lanka has developed a signifcant multi-hazard warning system after the 2004 Tsunami. This includes provision for Cyclones, however there are no multi-level alerts based on storm serverity. Click on the buttons below to learn more:

CYCLONES

• Class I: Issued to allow no less than 36 hours but no more than 48 hours ahead of gusts of 120km per hour
• Class II: Issued to allow 12 hours of daylight ahead of predicted gusts of 120km per hour
• Class III: Issued to allow 6 hours of daylight ahead of 120km per hour gusts
• Class IV: 120km per hour recorded and expected to continue

Mauritius has a signifcant Cyclone alert framework based on prepartion time:

Mauritius

CYCLONES

• Flooding from rainfall
• Storm Surges

In this simplicaity though the scale does not take into account other potential danegrs like:

Uses & Limitations

The US National Hurricane Centre uses this scale to assess what warnings to issue. The simple scale provides easily understandable information to decision makers and the public alike as to what action to take.

Learn more:

Fact Sheet: Sri Lankas early warning system

UN Adaptation Report: EWS in Sri Lanka

• High: You may need to take action as we are expecting...
• Medium: We should be prepared for...
• Low: Be aware of the possibility...

Case Study: Dominica

Dominica has a slightly different system with 4 colour levels and 3 confidence levels based on forecasted hurricanes or tropical storms. The confidence levels are as follows:

Evaporation: Warm seawater evaporates into the lower atmosphere. Rising air: Converging winds force warm, moist air to rise. Cloud formation: As the air rises, it cools and condenses into clouds and thunderstorms. Low pressure: The rising air creates an area of low pressure, which causes more air to rush in. Rotation: The air in the hurricane rotates due to the Coriolis effect, which causes winds to curve based on the Earth's rotation.

Hurricanes are formed when warmer sea waters eveoprates and winds cause it to rise. This then creates clouds and low pressure drawing in more air. Watch this video to learn more:

How do Hurricanes form?

Academic Studies:

Disaster Risk Management in Vietnam

Community Based EWS in Coastal Vietnam

In June 2023, a sevre cyclone hit Gujarat in India with speeds up to 125 kph. Over 100,000 were evacuated due to updated, EWS. Two shepards died. Just two years earlier 100 people died from a similar cyclone.

Early Warning in Action

These are some examples of alerts given in Sri Lanka. Left is a Sri Lankan Red Cross alert and below is a notice for a given daywithout potential cyclone activity.

Sri Lankan Alerts

Indias Early Warning System

Presentation: Indias Early warning System

To learn more about India's early warning system across the range of hazards the Ministry of Earth Sciences plans for, click the link below:

References:

This tool is intended for educational purposes only. Information on indivual countries where further information was gathered from national meterological and disaster management agencies - links are provided on relevatn slides. Otherwise the following review article by Olaf Neußner was used to create this tool (click below to access):

Academic Studies:

EWS and evacuation: cyclones in Philippines and Dominica

Disaster Warning System in the Philippines: Case Study

Fuzzy Logic Model of EWS for Typhoon Preparedness

Beyond Early: Decision Support for Improved Typhoon EWS

Early Warning Systems

The UN Early Warnings for All initative aims to provide early warning capacity for everyone on Earth. It is founded upon interconnected pillars, working alongside each other to detect, warn and respond to hazards.

• Increase forecasting of secondary hazards
• Strengthening cooperation between National Forecasting Services and Disaster Risk institutions
• Increasing public awareness of warnings

CREWS Caribbean

Climate Risk Early Warning Systems

CREWS is an initiative the 'strengthen and streamline' hydrogemterological early warning in the Caribbean.

Learn more:

Medellín Multi-hazard early warning system

Improving hurricane prepardness in colombia

Hong Kong Alert Levels

More Warning Signals Information:

Below you can see further information on the warning signal levels aswell as an example of signal bulletin. Alongside warning signals, PAGASA advises on storm locations, intensity, expected precipitation and potential community impacts. Then based on these warnings local authorities order evacuations.

Academic Studies:

SOCIAL MEDIA & EWS: A case study of Typhoon Etau (japan)

Multi-Hazard Early Warning System in Japan

Alongside the alert level organisations disseminate more information giving further context and advice for people and businesses to act upon. These often include:

• Expected weather conditions (wind speeds)
• Areas at risk
• Likely or potential impacts (flooding)

• Potential time frame

Warnings

Further information alongside alert level

How do Cyclones and Typhoons differ?

Cyclones form in the Indian and Australian basins between 5° - 30° latitude either north or south of the equator.

Scale Compairson