NOAA

Ensuring Storm Tide Data 

Are Available When Needed Most

NOAA Sentinels are water level observing stations which have been strengthened 

to deliver real-time storm tide data during severe coastal events. Elevated atop 

substantial single pile platforms, these stations are specifi cally designed to withstand 

category four hurricanes. NOAA Sentinels measure and disseminate real-time 

water level and meteorological observations. All of this information helps coastal 

authorities prepare for, mitigate, and respond to storm tides generated by severe 

coastal storms.

HOW DO NOAA SENTINELS HELP PROTECT COASTAL COMMUNITIES?

Coastal communities are vulnerable to a wide range of coastal hazards including 

severe storm events, sea level rise, tsunamis, shoreline erosion, and coastal ecosystem 

degradation. Preventive actions and emergency response planning can help to reduce 

this vulnerability, bolster community resilience, and help communities recover from 

disruptions in basic services and economic activity.

NOAA water level and meteorological data have long been key components of coastal 

decision making before, during, and after major storm events. This information is 

critical for developing vulnerability assessments, providing more accurate marine 

weather and fl ood forecasts, evacuation planning and execution, determining when 

to open and close locks, and facilitating the reopening of ports after storms pass. 

The NOAA Sentinels hardening effort was borne out of NOAA’s recognition of the 

critical need for accurate data at the height of storms.

WHAT ARE NOAA SENTINELS?

The Center for Operational Oceanographic Products and Services (CO-OPS), part 

of NOAA’s National Ocean Service (NOS), is responsible for operating the National 

Water Level Observation Network (NWLON). By virtue of their location at the 

ocean’s edge, water level observing stations are exposed to severe damage by the 

very storms which make their operation so important. Strengthening key NWLON 

stations ensures that observations of water level, wind speed and direction, barometric 

pressure, and air and water temperature will be available when the information is 

needed most.

NOAA Sentinels are large single-pile structures. A single-pile structure presents a 

minimal profi le to a storm coming from any direction. Engineering specifi cations 

based on Category 4 generated wind and wave action analysis determined that the 

platforms stand at least 25 feet above the sea surface on a 4-foot diameter single pile. 

The piles are driven 60-80 feet into the seafl oor to ensure stability.
Sentinel Locations in the Gulf

Hurricane Katrina QuickLook

WHERE ARE NOAA SENTINELS?

NOAA Sentinels are deployed in coastal areas most vulnerable to 

severe storms such as Hurricanes Rita and Katrina. Sentinels are being 

extablished at four locations which were selected based on two objectives; 

re-establish NWLON stations either destroyed or heavily damaged by 

recent hurricanes; and establish new stations in areas identifi ed as gaps 

in the NWLON. Additional Sentinels will be established as funding 

becomes available.

WHAT PRODUCTS COME FROM NOAA SENTINELS?

Real-time data from all of NOAA’s NWLON stations are available on the 

internet http://tidesonline.nos.noaa.gov and show observed water levels 

in relation to tidal datums and predicted levels. During tropical storm 

warnings CO-OPS provides Storm QuickLook, a compilation of near realtime oceanographic and meteorological observations within the affected 

coastal area. An overlay map of NOAA satellite imagery and National Weather Service forecast information displays storm 

characteristics relative to CO-OPS water level measurement stations. The plotted data are summarized along with the time 

of the next predicted high tides. 

Sentinels will provide vertical control for emergency 

hydrographic surveys required to re-open ports and 

harbors for commerce. Post-storm reports are created 

using verifi ed data to provide an overview of the storm 

water level impacts. Technical reports also supply a 

more detailed analysis of storm-induced water levels 

and historical storm comparisons.

In addition to the real-time uses of NOAA Sentinels 

information, archived data are used in many coastal 

protection engineering projects including levee 

construction and evacuation route planning, and 

verifi cation of storm surge forecast models.

FOR MORE INFORMATION

NOAA’s Center for Operational Oceanographic 

Products and Services (CO-OPS) mission is turning 

operational oceanographic data into meaningful 

information for the Nation. To access NOAA’s realtime water level, currents, and meteorological data, as 

well as background information on CO-OPS products 

and services, visit the CO-OPS website at

http://tidesandcurrents.noaa.gov.

NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION

CENTER FOR OPERATIONAL OCEANOGRAPHIC PRODUCTS AND SERVICES

1305 East-West Highway, Silver Spring, MD 20910

301-713-2981