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PUBLIC INFORMATION STATEMENT
NATIONAL WEATHER SERVICE NEW YORK NY
600 AM EDT FRI APR 26 2024

...This Is Severe Weather Awareness Week...

This statement covers flash floods.

Since 1996, flash floods have accounted for over 10 deaths and more 
than 125 million dollars in property damage across the Tri-State 
area.

Flash floods can occur anywhere from within a few minutes to a few 
hours of excessive rainfall. The two key elements contributing to 
flash flooding are rainfall intensity and duration.

Slow moving thunderstorms moving over the same area can produce 
rainfall rates in excess of 2 inches per hour for several hours. 
These storms, which are more common from late spring through early 
fall, can produce flash flooding of streets, poor drainage areas, 
small streams and rivers.

Never drive through a flooded roadway. Turn around, do not drown. It 
takes only 6 inches of running water to knock down an adult, just 12 
inches of running water to carry away a small car, and 2 feet of 
rushing water can carry away most vehicles. It is never safe to 
drive or walk into flood waters.

When there is a potential for flooding beyond 48 hours, our National 
Weather Service Forecast Office on Long Island NY will provide this 
information in our Hazardous Weather Outlook text product.

Flood Watches are issued by our NWS office when there is a potential 
for any type of flooding, within 48 hours.

Flash Flood Warnings will be issued when any type of flooding, 
except tidal flooding, will create an immediate threat to life and 
property within 6 hours. Our office uses a combination of weather 
radar, rain gages, and volunteer Skywarn Spotter observations to 
issue warnings.

Flash flood warnings are Impact-Based. This means that these 
warnings and follow-up statements include machine-readable tags 
which will appear at the bottom of the messages. Among these tags 
will be the damage threat. If considerable or catastrophic damage is 
tagged, the warnings will be disseminated as Wireless Emergency 
Alerts, in addition to the standard dissemination methods. 

The Catastrophic tagged flash flood warning is the Flash Flood 
Emergency. These events are extremely rare and life threatening, 
like what occurred during the July 9th 2023 flooding across the 
Lower Hudson Valley, Post Tropical Depression Ida in September 2021 
and the August 2014 Suffolk County flood. If a Flash Flood Emergency 
is issued for your area, you need to take immediate personal life 
saving action! Public safety officials may not be able to help you. 
If in a safe and dry location stay put, if not, get to higher ground 
immediately!

The final statement will cover a review of topics presented during 
this week.

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