A severe thunderstorm watch is a statement issued by weather forecasting agencies to advise the public that atmospheric conditions in a given region may lead to the development of severe thunderstorms within several hours1. This alert indicates that conditions are favorable for severe thunderstorm development, but it does not guarantee that storms will actually occur.
The National Weather Service defines a severe thunderstorm as any storm that produces one inch hail or larger in diameter and/or winds equal to or exceeding 58 miles per hour. These criteria distinguish severe thunderstorms from ordinary thunderstorms, which may still produce heavy rain and lightning but lack the intensity to cause significant damage.
The Three-Tiered Warning System
Weather forecasters use a systematic three-tiered approach to alert the public about severe weather threats:
Outlooks are issued well in advance when conditions are uncertain, often three or more days before potential severe weather. The Storm Prediction Center issues convective outlooks that depict severe thunderstorm threats across the contiguous United States.
Watches are issued when conditions become more favorable and forecasters gain greater certainty about potential hazards. A severe thunderstorm watch encourages planning, preparation, and increased awareness.
Warnings are issued when severe weather is either imminent or has been reported, requiring immediate action to protect life and property.
How Severe Thunderstorm Watches Are Issued
Severe thunderstorm watches are issued by the NOAA Storm Prediction Center after consultation with local National Weather Service offices. The Storm Prediction Center, located in Norman, Oklahoma, is dedicated to providing daily forecasts and risk assessments for severe thunderstorms across the contiguous United States.
These watches typically cover large areas, spanning numerous counties or even multiple states, and are usually issued for a duration of 4 to 8 hours. The size and duration can vary depending on the specific weather situation and atmospheric conditions.
What to Expect During a Watch
When a severe thunderstorm watch is in effect, it’s important to understand that you may experience deceptively fair weather with few clouds before thunderstorms actually develop. The watch simply means that atmospheric ingredients are beginning to come together, and severe thunderstorms may develop if conditions continue to align.
During a watch, you should continue normal activities but remain alert for changing weather conditions and possible warnings. It’s crucial to monitor NOAA Weather Radio or local media for updates and be prepared to take shelter if conditions deteriorate.
Safety Recommendations
While under a severe thunderstorm watch, prepare for potential severe weather by securing outdoor objects that could blow away or cause damage. Avoid natural lightning rods such as golf clubs, fishing poles, and metal equipment, as lightning is attracted to metal objects.
If you’re planning outdoor activities, consider postponing them if storms appear imminent. Keep a battery-operated radio or NOAA Weather Radio available to stay informed about changing conditions.
Have disaster supplies readily available, including flashlights, extra batteries, first aid kit, emergency food and water, and essential medicines. Check on neighbors who may require special assistance, including infants, elderly individuals, and people with disabilities.
Understanding the Difference: Watch vs. Warning
The key distinction between a watch and a warning lies in timing and certainty. A severe thunderstorm watch means conditions are favorable for severe weather development, while a severe thunderstorm warning indicates that severe weather is imminent or already occurring.
Warnings are typically issued for much smaller areas and shorter durations, usually lasting 30 to 60 minutes and covering parts of one to several counties. When a warning is issued, immediate action is required to protect life and property.
The Role in Public Safety
Severe thunderstorm watches serve as an essential early warning system, giving communities time to prepare before dangerous weather arrives. This advance notice allows emergency managers, media, and the public to take appropriate precautions and develop action plans.
Understanding and responding appropriately to severe thunderstorm watches can significantly reduce the risk of injury and property damage when severe weather strikes. By staying informed and prepared, communities can better weather nature’s most powerful storms.