Special marine warning

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A Special Marine Warning (Specific Area Message Encoding SAME Code: SMW) is a warning product issued by the U.S. National Weather Service for potentially hazardous marine weather conditions usually of short duration (up to 2 hours) producing sustained marine thunderstorm winds or associated gusts of 34 knots or greater; or hail 3/4 inch or more in diameter; or waterspouts affecting areas included in a Coastal Waters Forecast, a Nearshore Marine Forecast, or a Great Lakes Open Lakes Forecast that is not adequately covered by existing marine warnings. It is also used for short duration mesoscale events such as a strong cold front, gravity wave, squall line, etc., lasting less than 2 hours and producing winds or gusts of 34 knots or greater.[1]


  1. ^ "Special Marine Warning Definition". NWS. Retrieved 28 September 2013.