A dust storm warning (SAME code: DSW) is issued by the National Weather Service in the United States when blowing dust is expected to frequently reduce visibility to 1⁄4 mile (400 m) or less, generally with winds of 25 miles per hour (40 km/h) or more.
[1] Beginning November 1, 2018, the National Weather Service issued these dust storm warnings in a polygon- and storm-based format, similar to the format of severe thunderstorm and tornado warnings.
In addition to the new dust storm warning format, a lesser-impact dust advisory will be issued by the National Weather Service if the criteria for a warning are not met and if travel impacts are still expected.
[2] The following is the first issuance of the new "storm-based" dust storm warnings, which is in use as of June 19, 2018.
[3] The following is an example of the previous-format dust storm warning issued by the National Weather Service in Tucson, Arizona.