GUIDE MAP

Early Warning levels

Hurricanes, Tropical Cyclones and Typhoons

Hurricanes

Typhoons

Tropical cyclones

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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:

Hurricanes

United STATES

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

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

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

COLOMBIA

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

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

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Typhoons

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

CHINA

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.

• 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

Typhoons

Japan

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.

Typhoons

Vietnam

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):

Typhoons

Philippines

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

• 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

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Tropical cyclones

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

CYCLONES

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.

• 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

CYCLONES

india

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

• 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

Mauritius

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

• 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

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.

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

• Flooding from rainfall
• Storm Surges

Learn more:

Fact Sheet: Sri Lankas early warning system

UN Adaptation Report: EWS in Sri Lanka

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:

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

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.

How do Hurricanes form?

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:

Academic Studies:

Community Based EWS in Coastal Vietnam

Disaster Risk Management in Vietnam

Early Warning in Action

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.

Sri Lankan Alerts

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.

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:

Presentation: Indias Early warning System

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:

Beyond Early: Decision Support for Improved Typhoon EWS

Disaster Warning System in the Philippines: Case Study

Fuzzy Logic Model of EWS for Typhoon Preparedness

EWS and evacuation: cyclones in Philippines and Dominica

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.

CREWS Caribbean

Climate Risk Early Warning Systems

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

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

Learn more:

Improving hurricane prepardness in colombia

Medellín Multi-hazard early warning system

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:

Multi-Hazard Early Warning System in Japan

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

Warnings

Further information alongside alert level

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

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