Strong Thunderstorm Over Southern Guam Waters; Boaters Advised to Seek Safe Harbor


Strong Thunderstorm Over Southern Guam Waters; Boaters Advised to Seek Safe Harbor

The National Weather Service (NWS) Weather Forecast Office Guam issued a marine weather statement for Guam. A strong thunderstorm is over the waters of southern Guam. The thunderstorm is capable of producing winds to around 35 knots. It is located near Cocos Island, 12 nautical miles south of Agat, moving north at 25 knots. Mariners can expect gusty winds to around 30 knots, locally higher waves, and lightning strikes. Boaters should seek safe harbor immediately until the storm passes.  

The following NWS advisories remain in effect:

flash flood watch remains in effect for Guam, Rota, Tinian, and Saipan, through this afternoon. Brief heavy showers and thunderstorms this afternoon may cause periods of flooding.

Through this afternoon:

  • Avoid driving on flooded roads;
  • If driving, be alert for low visibilities and slippery roads in heavy rain;
  • Slow down where water is ponding on the road;
  • Turn Around, Don’t Drown. Avoid walking or driving through flood waters. Just 6 inches of moving water can knock you down, and 2 feet of water can sweep your vehicle away;
  • Do not camp, park, or hike along streams, rivers, and creeks during heavy rainfall. These areas can flood quickly and with little warning.

small craft advisory remains in effect for the coastal waters of Guam, Rota, Tinian, and Saipan, until 6 a.m. Monday. South winds of 10 to 20 knots, with gusts up to 30 knots, and choppy seas between 5 to 7 feet are expected. Largest seas are likely near Guam. Expect reduced visibility at times due to brief heavy showers. Inexperienced mariners, especially those operating smaller vessels, should avoid navigating in hazardous conditions.

The Offices of Guam Homeland Security and Civil Defense (GHS/OCD) remind the community to practice caution while traveling in rainy conditions, driving below the speed limit and allowing enough braking distance between vehicles.

Visit the following links for the latest advisory information:

For more information, contact GHS/OCD Public Information Officer Jenna G. Blas at (671) 489-2540 or via email at



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June 2018 is Typhoon Preparedness Month