When a hurricane or tropical storm develops in the Atlantic or Eastern Pacific Ocean, meteorologists at the National Hurricane Center issue a variety of products, including watches and warnings, to keep the public informed about the dangers faced along the tropical storm’s projected track.
The primary goal of any NHC product is to protect life and property, so it’s important to understand what it means when a Hurricane or Tropical Storm Watch or Warning is issued for your town.
The NHC issues advisories every six hours for all active Atlantic and Eastern Pacific tropical cyclones. These updates always occur at 5 a.m., 11 a.m., 5 p.m. and 11 p.m. Eastern daylight time. But in the case that watches and warnings are in effect for any land areas, the NHC provides additional updates at the three-hour intervals between those times, which might include new watches or warnings.
What is a Tropical Storm Watch, Hurricane Watch and Storm Surge Watch?
- Tropical Storm Watch: Tropical-storm-force winds (sustained winds of 39 to 73 mph) are possible within the storm watch area, generally within 48 hours. These winds may be accompanied by storm surge, coastal flooding and/or river flooding.
- Hurricane Watch: Hurricane-force high winds (sustained winds of 74 mph or greater) are possible within the watch area, generally within 48 hours. These winds may be accompanied by storm surge, coastal flooding and/or river flooding.
- Storm Surge Watch: There is a possibility of life-threatening inundation from rising water moving inland from the shoreline somewhere within the watch area, generally within 48 hours.
Watches do not mean these disaster conditions will definitely occur; they only mean those dangerous conditions are possible, but you still need to take Tropical Storm Watches seriously.
What is a Tropical Storm Warning, Hurricane Warning and Storm Surge Warning?
- Tropical Storm Warning: Tropical-storm-force winds are expected within the storm warning area within 36 hours. These winds may be accompanied by storm surge, coastal flooding and/or river flooding.
- Hurricane Warning: Hurricane-force winds are expected somewhere within the emergency warning area. The National Hurricane Center issues Hurricane Warnings 36 hours before the most likely arrival of tropical-storm-force winds to give you time to complete your preparations. These winds may be accompanied by storm surge, coastal flooding and/or river flooding. Hurricane Warnings can remain in effect when dangerously high water, or a combination of dangerously high water and exceptionally high waves, continues, even though winds may be less than hurricane force.
- Storm Surge Warning: There is a danger of life-threatening inundation from rising water moving inland from the shoreline somewhere within the warning area, generally within 36 hours.
- Extreme Wind Warning: Extreme sustained winds of major-hurricane force (115 mph or greater), usually associated with the eyewall, are expected to begin within one hour. Take immediate shelter in the interior portion of a well-built structure to secure safety.
The difference between Tropical Storm and Hurricane Warnings vs. Watches is that warnings are more dire than watches because they mean the storm is imminent, so all preparations should be rushed to completion when a warning is issued for your town.