Difference between a flood watch and a flood warning

A (coastal) flood watch is issued when coastal flooding is possible within the next one to two days.  That flooding has to have the potential to be moderate, major, or record in order for a watch to be issued.

A (coastal) flood warning is issued when coastal flooding is occurring or is expected to happen in the next day.  Again, moderate flooding or worse is needed to trigger a warning.  If the flooding is only minor, then a coastal flood advisory will be issued instead.

Tidal flooding is a year-round hazard along the South Jersey shore and a way of life for island residents.

In the winter, Nor'easters can cause it. In the summer, it's tropical storms and hurricanes that pose the threat. Even the simple setup of a full or new moon with an onshore wind from the east and northeast can cause water levels to rise in the back bays all year long.

The National Weather Service continuously monitors the expected water levels along the coast, and will issue flood related watches and warnings when the threat of tidal flooding rises. But what does a coastal flood warning mean, and how does it differ from a coastal flood advisory?

COASTAL FLOOD WATCH: Issued when there is a potential for at least moderate tidal flooding in the next one to two days. The chance for moderate, major, or record flooding levels triggers a coastal flood watch.

COASTAL FLOOD WARNING: Issued when tidal flooding is occurring or likely to occur within the next day.  Flooding has to be at least moderate or higher in order for a coastal flood warning to be issued.

COASTAL FLOOD ADVISORY:   Issued when minor tidal flooding is expected to occur within the next 24 hours.  

In South Jersey, minor tidal flooding occurs most frequently and causes minor disruptions in the most flood prone areas.  Moderate flooding is more problematic, and causes more road closures and more properties to flood throughout the area. Major flooding is more rare, but is experienced during major Nor'easters like Jonas in January of 2016.

Never miss breaking news as it happens! Sign up now to receive alerts delivered to your inbox.

Meteorologist/Staff Writer

Recommended for you

Welcome to the discussion.

Keep it Clean. Please avoid obscene, vulgar, lewd, racist or sexually-oriented language.
Don't Threaten. Threats of harming another person will not be tolerated.
Be Truthful. Don't knowingly lie about anyone or anything.
Be Nice. No racism, sexism or any sort of -ism that is degrading to another person.
Be Proactive. Use the 'Report' link on each comment to let us know of abusive posts.
Share with Us. We'd love to hear eyewitness accounts, the history behind an article.

PLEASE BE ADVISED: Soon we will no longer integrate with Facebook for story comments. The commenting option is not going away, however, readers will need to register for a FREE site account to continue sharing their thoughts and feedback on stories. If you already have an account (i.e. current subscribers, posting in obituary guestbooks, for submitting community events), you may use that login, otherwise, you will be prompted to create a new account.