National Weather Service United States Department of Commerce

On November 13, 2019, the Weather Forecast Office Guam will start using the new Impact-Based (IBW) Flash Flood Warning format. The new format is part of a national change that hopes to improve the communication of flash flood warning information by making it easier to identify the most valuable information. 

In addition to the change in information placement within the warning, machine-readable tags will change the dissemination of Wireless Emergency Alerts (WEA) received by mobile phones. This change in WEA receipt is currently scheduled to occur on or after December 16, 2019.

For additional information on the product format and features, please download the information sheet (pdf) at this link.