The National Weather Service Alert System
The National Weather Service (NWS) issues weather alerts to protect life and property. Understanding the difference between watches, warnings, and advisories can help you make informed decisions about your safety. The alert system is designed to give you as much advance notice as possible about dangerous weather conditions.
Alert Levels Explained
Outlooks
Outlooks are issued days in advance to indicate that conditions may be favorable for hazardous weather. The Storm Prediction Center issues convective outlooks on a 1-5 risk scale, with categories from Marginal (1) through High (5). An outlook does not mean severe weather will definitely occur, but you should monitor conditions and have a plan ready.
Watches
A watch means conditions are favorable for a particular type of severe weather to develop. Watches are typically issued hours in advance and cover large geographic areas. When a watch is issued, you should prepare your emergency plan, charge devices, and stay tuned to weather updates. Common watches include Tornado Watch, Severe Thunderstorm Watch, and Winter Storm Watch.
Warnings
A warning means that hazardous weather is imminent or already occurring. Warnings require immediate action to protect life and property. When a warning is issued for your area, take shelter immediately if it involves tornadoes or severe thunderstorms. Warnings are more geographically specific than watches and typically last 30-60 minutes for thunderstorm-related events.
Advisories
Advisories fall between watches and warnings in severity. They indicate weather conditions that may cause inconvenience or be hazardous if caution is not exercised. Examples include Winter Weather Advisory, Dense Fog Advisory, and Wind Advisory. Take appropriate precautions but the situation is not as dire as a warning.
Common Alert Types
Tornado Warning
This is the most urgent weather alert. A tornado has been spotted by trained spotters or indicated by Doppler radar. Take shelter immediately in the lowest level of a sturdy building, away from windows, in an interior room or hallway. If you are in a mobile home, evacuate to a substantial structure.
Severe Thunderstorm Warning
A severe thunderstorm with winds of 58 mph or greater and/or hail 1 inch or larger in diameter is occurring or imminent. Move indoors and away from windows. These storms can produce damaging winds, large hail, dangerous lightning, and occasionally tornadoes.
Flash Flood Warning
Flash flooding is occurring or imminent. Move to higher ground immediately. Do not walk, swim, or drive through flood waters. Just six inches of moving water can knock you down, and two feet of water can float a car. Turn around, don't drown.
Hurricane Warning
Hurricane conditions (sustained winds of 74 mph or greater) are expected within 36 hours. Complete preparations and evacuate if ordered by local authorities. Hurricane warnings are issued well in advance to allow for evacuation of coastal and flood-prone areas.
Winter Storm Warning
Heavy snow, sleet, or freezing rain is expected. Limit travel and prepare for possible power outages. Stock up on food, water, and medications. Keep emergency supplies including flashlights, batteries, and warm clothing readily available.
Extreme Heat Warning
Dangerously hot conditions with temperatures and/or heat index values expected to exceed local criteria. Stay in air-conditioned spaces, drink plenty of water, and check on elderly neighbors. Heat is the number one weather-related killer in the United States.
How to Receive Alerts
Wireless Emergency Alerts (WEA) are sent directly to your cell phone for the most dangerous weather events. NOAA Weather Radio provides continuous broadcasts of weather information. The NWS also provides alerts through its website, social media, and the WeatherStream360 live map.
What to Do When You Receive an Alert
Read the entire alert carefully, noting the affected area, timing, and recommended actions. Share the information with family members and neighbors. Follow the recommended protective actions. Monitor the situation for updates, as alerts can be upgraded, downgraded, or extended.