Watch vs warning › Severe thunderstorm watch vs warning
Severe thunderstorm watch vs warning
A severe thunderstorm watch means severe storms are possible near you. Be ready. A severe thunderstorm warning means severe weather has been reported or picked up on radar. Get inside a sturdy building now.
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A severe thunderstorm can produce a tornado with little notice. Treat a severe thunderstorm warning as a reason to be somewhere safe, not a reason to go watch.
What the National Weather Service says
Severe Thunderstorm Watch
Severe thunderstorms are possible in and near the watch area.
- Issued by
- The Storm Prediction Center issues all severe thunderstorm watches. Your local National Weather Service office relays them.
- Area covered
- The watch area is typically large, covering numerous counties or even states.
- How long it lasts
- Watches last during a two to eight hour period. Each one carries an expiration time set when it is issued.
Severe Thunderstorm Warning
Severe weather has been reported by spotters or indicated by radar. Warnings indicate imminent danger to life and property.
- Issued by
- Your local National Weather Service forecast office issues severe thunderstorm warnings.
- Area covered
- Warnings typically encompass a much smaller area, around the size of a city or small county.
- How long it lasts
- The expiration time is written in the alert. Check it there.
A thunderstorm is considered severe when it contains one inch or larger diameter hail and/or wind gusts of 58 miles an hour or greater. Source: NWS Louisville, cited at the end of this page.
With any severe thunderstorm there is always the possibility of tornadoes.
Watch duration and who issues watches come from the Storm Prediction Center FAQ, cited at the end of this page.
What to do
If a severe thunderstorm watch is issued
- Stay informed and be ready to act if a severe thunderstorm warning is issued.
- Decide now which sturdy building you would go to.
- Turn on the emergency alerts in your phone settings and check your weather radio batteries.
- Bring in or tie down anything outside that could blow around.
- Move vehicles under cover if you can do it safely.
- Charge your phone. Damaging wind can take the power out.
If a severe thunderstorm warning is issued
- Take shelter in a substantial building. Go inside now.
- If you are in a mobile home, leave it and go to a substantial building. Mobile homes can blow over in high winds.
- Stay away from windows.
- Move to an interior room if the alert mentions destructive wind or large hail.
- Stay off the road if you can. If you are already driving, slow down and be ready for hail and sudden gusts.
- Stay inside until the warning expires or the National Weather Service cancels it.
Common questions
What counts as a severe thunderstorm?
A thunderstorm is considered severe when it contains one inch or larger diameter hail and/or wind gusts of 58 miles an hour or greater. Heavy rain and lightning alone do not make a storm severe, even though both can kill you. With any severe thunderstorm there is always the possibility of tornadoes.
Source: www.weather.gov/lmk/ref_svrWho issues a severe thunderstorm watch?
The Storm Prediction Center issues all severe thunderstorm watches and tornado watches. All warnings are issued by local National Weather Service offices. That split is why a watch covers a large area and a warning covers a small one.
Source: www.spc.noaa.gov/faqShould I take shelter during a severe thunderstorm warning?
Yes. A severe thunderstorm warning means severe weather has been reported by spotters or indicated by radar, and there is imminent danger to life and property. Take shelter in a substantial building. If you are in a mobile home, leave it and go to a substantial building, because mobile homes can blow over in high winds.
Source: www.weather.gov/safety/thunderstorm-wwIs a severe thunderstorm warning as serious as a tornado warning?
They are different hazards with different actions, and both mean imminent danger to life and property. A severe thunderstorm warning sends you inside a substantial building and away from windows. A tornado warning sends you to a small interior room on the lowest floor. If a severe thunderstorm warning mentions a destructive damage threat, treat it with tornado-level urgency and move to an interior room.
Source: www.weather.gov/safety/thunderstorm-wwWhy did I not get a phone alert for a severe thunderstorm warning?
Severe thunderstorm warnings are only sent to cell phones as Wireless Emergency Alerts when the damage threat is destructive. Most of them are not, so most do not reach your phone. Do not use your phone as your only source during storms.
Source: www.weather.gov/wrn/weaHow a severe thunderstorm alert reaches your phone
Severe Thunderstorm Warnings go to cell phones as Wireless Emergency Alerts only when the damage threat is destructive. Most severe thunderstorm warnings do not trigger a phone alert.
Severe thunderstorm watches never trigger a phone alert. The National Weather Service list of alerts sent to phones contains warnings only.
This is the hazard where a quiet phone misleads people most. Use a weather radio or a local news source during storms.
Source: www.weather.gov/wrn/weaHow a severe thunderstorm alert reaches you without cell service
NOAA Weather Radio All Hazards broadcasts official Weather Service warnings, watches, forecasts and other hazard information 24 hours a day, 7 days a week, directly from the nearest National Weather Service office.
It carries every severe thunderstorm watch and warning, including the ones that never reach your phone. It needs a special radio receiver or scanner.
Source: www.weather.gov/nwrAbout outdoor sirens
Cities and counties own outdoor warning sirens and decide when to sound them. Some sound them for severe thunderstorm warnings and some do not, and the National Weather Service does not sound them at all.
Sirens are built to warn people who are outdoors. Do not make a siren your only alert.
Source: www.weather.gov/dvn/sirenFAQ