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Marine, Tropical, and Tsunami Services Branch
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Marine, Tropical, and Tsunami Services


The National Weather Service's Marine, Tropical, and Tsunami Services Branch (W/AFS26) is responsible for oversight of the Marine, Tropical, and Tsunami Services Programs. The programs provide current, accurate information relating to the U.S. coast, coastal and offshore waters, the Great Lakes, and the open oceans. This information aims to:

  • Ensure the safety of life and protection of property
  • Promote international and interstate commerce by improving the efficiency of marine operations
  • Mitigate environmental impacts
  • Enhance the quality of life for the United States

Transport by water is generally the most economical and efficient means to move goods. Helping marine traffic avoid hazardous weather benefits Americans by keeping costs down, thus making products more affordable. More than 90 percent of the goods imported into the United States arrive via the oceans. Maritime commerce results in a contribution of $78.6 billion annually and generates nearly 16 million jobs. One out of six jobs in the U.S. is marine related. Further, over 77 million Americans enjoy recreational boating, an industry that generates nearly $18 billion annually in sales of boats and related materials.*

Death from rip currents, hurricanes and associated flooding represent a major share of U.S. weather-related fatalities. According to the CDC, severe weather conditions contributed to 148 (61%) of the fatal disasters aboard fishing vessels for the period 2000-2010.

According to the CIA World Factbook, the coastline of the United States and its territories extends for 19,924 km (10,758 nautical miles, 12,380 statute miles)

Coastal areas in the U.S. are home to a wealth of natural and economic resources and include some of the most developed areas in the nation. The narrow coastal fringe that makes up 17 percent of the nation's contiguous land area is home to more than half of its population. In 2010, 123.3 million people, or 39 percent of the nationís population lived in Coastal Shoreline Counties.**

Using the weather analyses and forecast guidance provided by NCEP, along with radar, satellite, and in-situ observational data, NWS marine weather forecasters issue wind, sea state, and significant weather warnings, forecasts, and weather statements. These are essential to the conduct of safe and efficient maritime operations and for the protection of the marine public.

The collection of weather observations is vital to accurate weather forecasting, and especially so over the waters where weather stations are few and far between. Thousands of vessels worldwide are Volunteer Observing Ships (VOS), sending observations every few hours which are used by marine forecasters and computer modelers to improve the accuracy of the forecasts. The National Data Buoy Center (NDBC) maintains 103 buoys and 47 fixed C-MAN stations in the oceans and the Great Lakes.

Marine forecasts are also issued as needed to aid in search and rescue operations, the containment and cleanup of oil spills or support to other disasters such as plane crash recovery operations.

A Tsunami Warning System is in place to help minimize loss of life and property. The National Tsunami Warning Center (NTWC) in Palmer, Alaska monitors for earthquakes and subsequent tsunami events. If a tsunami is generated, they issue tsunami advisories, watches and warnings, as well as tsunami information statements for the U.S. mainland, Canada, Puerto Rico and the U.S. Virgin Islands. The Pacific Tsunami Warning Center in Ewa Beach, Hawaii provides similar services for the Aloha state as well as all other American territories in the Pacific. PTWC also serves s the primary operational headquarters for the Pacific Tsunami Warning System, countries in the Caribbean Sea, and nations bordering the South China Sea (China, Macao, Hong Kong, Taiwan, Philippines, Malaysia, Brunei, Indonesia, Singapore, Thailand, Cambodia, Vietnam. The U.S. also hosts the International Tsunami Information Center.

*Source: Year of the Ocean Discussion Papers, Office of the Chief Scientist, NOAA, 1998.

**Source: National Coastal Population Report


National NWS Marine Forecasts Page:

  • Marine Forecasts
    Forecasts, warnings, observations, maps, pubs, broadcast info, contacts, etc.

High Seas Forecasts and Warnings:

Offshore Forecasts and Warnings:

Coastal and Great Lakes Forecasts and Warnings:

Ice Products:

Model Guidance and Products

Hurricane Forecasts and Warnings:

Tsunami Warnings and Information:


Awareness Weeks:



Warning and Forecast Area Maps:

Explanation of Codes Used in Various Marine Text Forecasts and Weather Broadcasts:

Service Assessments:

Performance Statistics:

Interagency Agreements:


This and That:

National Weather Service
Analyze, Forecast, and Support Office
Marine, Tropical, and Tsunami Services Branch (W/AFS26)
Last modified: Apr 01, 2015
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