Guam Coastal Waters
Gale Warning and Hazardous Seas Watch in force. Tonight: Southwest wind 20 to 30 kt with frequent gusts to 40 kt. Seas 14 to 17 ft. Scattered showers with isolated thunderstorms.
Guam Coastal Waters on the map
The zone and the zones around it, tinted where a marine warning or advisory is in force. Tap a neighboring zone to open its forecast.
- Tropical Storm Warning
- Gale Warning
Now
The nearest stations reporting each, as of Fri, Oct 2, 6:48 PM GMT+10.
- Wind
- SW 12 kt, gusts 18 kt at PGBP7
- Water
- 86°F at APRP7
Alerts in force
Gale Warning from Fri, Oct 2, 2:45 PM GMT+10 until Sat, Oct 3, 5:00 PM GMT+10
Gale Warning issued October 2 at 2:45PM ChST until October 3 at 5:00PM ChST by NWS Tiyan GU
The full text
* WHAT...For the Gale Warning, southwest winds 20 to 30 kt with frequent gusts up to 40 kt and seas 14 to 20 feet expected. For the Small Craft Advisory, southwest winds 25 to 30 kt with gusts up to 40 kt and seas 12 to 14 feet. For the Hazardous Seas Watch, very steep and hazardous seas 15 feet or greater possible. * WHERE...Guam and Rota Coastal Waters. * WHEN...For the Gale Warning, until 5 PM ChST Saturday. For the Small Craft Advisory, until 5 AM ChST Friday. For the Hazardous Seas Watch, from Saturday afternoon through Sunday afternoon. * IMPACTS...Strong winds will cause hazardous seas which could capsize or damage vessels and reduce visibility. * ADDITIONAL DETAILS...Combined seas of 14 to 20 feet tonight will continue Saturday, then gradually diminish. West to southwest winds will be strong to gale-force.
Inexperienced mariners, especially those operating smaller vessels, should avoid boating in hazardous conditions.
Hazardous Seas Watch from Sat, Oct 3, 5:00 PM GMT+10 until Sun, Oct 4, 5:00 PM GMT+10
Hazardous Seas Watch issued October 2 at 2:45PM ChST until October 4 at 5:00PM ChST by NWS Tiyan GU
The full text
* WHAT...For the Gale Warning, southwest winds 20 to 30 kt with frequent gusts up to 40 kt and seas 14 to 20 feet expected. For the Small Craft Advisory, southwest winds 25 to 30 kt with gusts up to 40 kt and seas 12 to 14 feet. For the Hazardous Seas Watch, very steep and hazardous seas 15 feet or greater possible. * WHERE...Guam and Rota Coastal Waters. * WHEN...For the Gale Warning, until 5 PM ChST Saturday. For the Small Craft Advisory, until 5 AM ChST Friday. For the Hazardous Seas Watch, from Saturday afternoon through Sunday afternoon. * IMPACTS...Strong winds will cause hazardous seas which could capsize or damage vessels and reduce visibility. * ADDITIONAL DETAILS...Combined seas of 14 to 20 feet tonight will continue Saturday, then gradually diminish. West to southwest winds will be strong to gale-force.
Inexperienced mariners, especially those operating smaller vessels, should avoid boating in hazardous conditions.
The forecast
Coastal Waters Forecast from National Weather Service Tiyan GU, issued Fri, Oct 2, 2:37 PM GMT+10, valid until Sat, Oct 3, 8:30 AM GMT+10. Wind in knots, seas in feet.
GALE WARNING IN EFFECT THROUGH SATURDAY AFTERNOON
HAZARDOUS SEAS WATCH IN EFFECT FROM SATURDAY AFTERNOON THROUGH SUNDAY AFTERNOON
- Tonight
- Southwest wind 20 to 30 kt with frequent gusts to 40 kt. Seas 14 to 17 ft. Scattered showers with isolated thunderstorms.
- Saturday
- Southwest wind 20 to 30 kt with frequent gusts to 40 kt. Seas 14 to 17 ft. Scattered showers with isolated thunderstorms.
- Saturday night
- Southwest wind 30 kt with occasional gusts to 40 kt. Seas 13 to 16 ft. Scattered showers with isolated thunderstorms.
- Sunday and Sunday night
- Southwest wind 30 kt. Seas 12 to 14 ft. Scattered showers with isolated thunderstorms.
- Monday
- Southwest wind 20 to 25 kt. Seas 10 to 13 ft. Wave Detail: West 11 ft at 10 seconds, southwest 6 ft at 8 seconds and northwest 3 ft at 13 seconds. A chance of showers with a slight chance of thunderstorms.
- Tuesday
- Southwest wind 15 to 20 kt. Seas 8 to 10 ft. Wave Detail: West 8 ft at 9 seconds, southwest 4 ft at 6 seconds and northwest 3 ft at 13 seconds. A chance of showers with a slight chance of thunderstorms.
- Wednesday
- West wind 10 to 15 kt. Seas 6 to 8 ft. Wave Detail: West 6 ft at 9 seconds, southwest 3 ft at 4 seconds and northwest 3 ft at 13 seconds. A chance of showers with a slight chance of thunderstorms.
Synopsis
Synopsis for Marianas Waters
Strong to gale force southwesterlies will continue. Combined seas of 15 to 20 ft will persist through Saturday, then begin to gradually diminish as Tropical Storm Choi-wan (26W) moves away from the northern CNMI and brings elevated southwest monsoon swell to the Marianas. For Saipan and Tinian, a Tropical Storm Warning remains in effect. For Guam and Rota, a Gale Warning remains in effect. Mariners should continue monitoring the forecast for changes in the coming days.
Buoys and stations nearby
The latest report from each station within reach of the zone, nearest first. Distances in nautical miles from the middle of the zone.
The past year
Warnings, watches and advisories the National Weather Service issued for this zone over the past 12 months, from the Iowa Environmental Mesonet’s archive.
The archive of past products did not answer just now.
What this means
Marine forecasts give wind in knots (1 knot is 1.15 mph) and seas in feet, except the high seas forecasts, which give seas in meters. Seas are the significant wave height, the average of the highest third of the waves; individual waves may be more than twice that. On the Great Lakes the forecast gives waves, not seas. "Wave Detail" splits the seas into the wind waves and each swell, with its direction and period.
Each coastal office writes a Coastal Waters Forecast for the bays, sounds and ocean out to 20 to 60 nautical miles, or on the Great Lakes a Nearshore Marine Forecast within 5 nautical miles of shore; the Open Lakes Forecast covers the rest of each lake. The Ocean Prediction Center and the National Hurricane Center write the Offshore Waters Forecasts out to about 250 nautical miles, and the High Seas Forecasts beyond. Forecasts are issued at least twice a day and updated when they go wrong.
- Small Craft Advisory
- Winds or conditions hazardous to small boats. The thresholds are set by each NWS region: typically sustained winds or frequent gusts of 20 to 25 knots up to 33 knots, and seas of 5 to 7 feet or more.
- Gale Warning
- Sustained winds or frequent gusts of 34 to 47 knots, not from a tropical cyclone.
- Storm Warning
- Sustained winds or frequent gusts of 48 to 63 knots, not from a tropical cyclone.
- Hurricane Force Wind Warning
- Sustained winds or frequent gusts of 64 knots or more, not from a tropical cyclone.
- Special Marine Warning
- A thunderstorm or squall over the water with winds or gusts of 34 knots or more, hail of 3/4 inch or more, or a waterspout, for up to two hours.
- Hazardous Seas Warning
- Wave heights or steepness at or above the office’s warning threshold, when the wind alone does not warrant a warning.
- Heavy Freezing Spray Warning
- Spray freezing on a vessel at 2 cm (3/4 inch) an hour or more.
- Tropical Storm and Hurricane Warnings
- Tropical storm (34 to 63 knots) or hurricane (64 knots or more) conditions expected within 36 hours. Watches: possible within 48 hours.
Nearby
Open the live map with marine zones and buoysThe hour-by-hour forecast for the middle of the zoneGuam BeachesEvery Guam and Micronesia zone
Sources
Coastal Waters Forecast CWFGUM from National Weather Service Tiyan GU, issued Fri, Oct 2, 2:37 PM GMT+10. Original at NWS. Buoy reports from the National Data Buoy Center. Past products from the Iowa Environmental Mesonet. Zone outlines from the NWS marine and offshore zone boundaries. Warnings and advisories from the NWS API, read 09:22 UTC. All public domain, from the National Weather Service.