Debuting Experimental Graphical Marine Wind Warnings

[By: NOAA]

The National Hurricane Center's Tropical Analysis and Forecast Branch is proud to announce the availability of our experimental Graphical Marine Wind Warnings.

Experimental Graphical Marine Wind Warnings are a graphical depiction of official marine warnings, based on cumulative wind speed (gridded) forecasts where the resultant warning reflects specific wind speed thresholds. 

This service will offer shapefiles of graphical marine wind warnings for the next 48 hours, encompassing all of the National Hurricane Center/Tropical Analysis and Forecast Branch’s tropical oceanic domains (tropical North Atlantic Ocean, Caribbean Sea, Gulf of America, and tropical Northeast Pacific Ocean).

This proposal enables the display of wind-based warnings in the high seas (areas of 34-47 kt, 48-63 kt, and 64 kt or greater) for both the 0-24 hour and 24-48 hour forecast periods, a capability beyond the previous wind speed-based warnings which were only available previously via text products and broad brush graphics.

The experimental phase will involve providing this information live, updated four times daily with each forecast cycle.

The intent is for these experimental warning graphics to be displayed in a user-friendly format for integration into various navigational ship software and displays, such as Electronic Chart Display and Information Systems (ECDIS). By accessing these products that indicate active Tropical Storm, Hurricane and Hurricane Force, Gale, or Storm Warnings, captains and mates can make better hazardous weather avoidance decisions for their vessels, crew, and cargo.

The Experimental Graphical Marine Wind Warning will be available at the following link: https://www.nhc.noaa.gov/gis/marine/warnings/

An example of the GMWW in the Atlantic (Hurricane Melissa, 2025):

 

 

 

 

 

 

 

The legend for the GMWW:

The Experimental Graphical Marine Wind Warnings are scheduled to be available daily by: 0445 UTC, 1045 UTC, 1645 UTC, and 2245 UTC. *Note: that because these are experimental, there may be times when they are not available or delayed.

GMWWs are valid for both tropical cyclones (tropical storms and hurricanes) as well as extratropical cyclones (gale, storm, and hurricane force).

For an explanation of the KML format, please visit: www.weather.gov/media/cio/Keyhole%20Markup%20Language.pdf which is provided by NOAA’s National Weather Service.

Input on the Experimental Graphical Marine Wind Warnings is being sought from users: https://www.surveymonkey.com/r/ExpGraphicalMarineWindWarnings_2025