Hurricane Ida rapidly intensified into a Category 4 hurricane just before making landfall near New Orleans on Aug. 29, causing catastrophic damage and flooding in the region. Although Ida weakened as it moved inland and eventually lost its tropical status, meteorologists predicted it would bring flooding to metro areas in the northeast after it merged with another storm system.
The New York Times and NPR were among the first news organizations to report that the system caused New York City to receive its first-ever “flash flood emergency.” Social media users who remembered New York City flood warnings for Hurricane Sandy and other weather events quickly expressed doubt over the reporting.
Did the National Weather Service issue its first-ever “flash flood emergency” for New York City during floods caused by Hurricane Ida?
Yes, the National Weather Service issued its first-ever “flash flood emergency” in New York City because of heavy rains dumped by Hurricane Ida. The NWS started using the term in 2014 as the most urgent type of flash flood warning used for the most dangerous floods.
WHAT WE FOUND
The National Weather Service’s Weather Forecast Office for the New York City metro area confirmed on Twitter it issued its first-ever flash flood emergency on Sept. 1, the night the remnants of Hurricane Ida passed through the area.
Iowa State University’s Iowa Environmental Mesonet, which keeps an archive of all NWS alerts dating back to 1986, lists no flash flood emergencies — or regular flash flood warnings that include the term “flash flood emergency” — issued by the NWS New York City metro office (OKX) before September 2021.
Flash flood emergencies are for “exceedingly rare situations” that pose “a severe threat to human life and catastrophic damage,” according to an NWS graphic posted to Twitter.
They are issued during flash flood warnings as more urgent warnings for more dangerous floods, only becoming an official part of the emergency alert system in 2014 and rarely issued since then.
This urgent, rarely used type of warning aligned with a Feb. 2020 change in how the NWS handles weather alerts sent to phones with a system called Wireless Emergency Alerts (WEA). The NWS limited flash flood warnings, which the public previously thought were over-alerted, to only broadcast through the WEA system if they were dangerous enough to cause “considerable'' or “catastrophic” damage.
A “catastrophic” flood is often one in which water rapidly rises to “levels rarely, if ever, seen” and can even rise above areas normally safe from flooding, according to an Aug. 3, 2021, NWS directive. The NWS warns of imminent “catastrophic” floods with flash flood emergencies.
So a “flash flood emergency” is a relatively new warning designed to be the most urgent flood alert the NWS issues.