The Commonwealth of the Northern Mariana Islands was placed under a tropical storm watch Thursday morning after Tropical Depression 12W moved west of Guam, according to the National Weather Service.
As of 7 a.m., 12W was located 50 miles west of Guam, 90 miles west-southwest of Rota, 150 miles southwest of Tinian and 160 miles southwest of Saipan near 13.5N 144.0E.
Maximum sustained winds were 30 mph.
The system was moving west-northwest at 2 mph and was expected to make a gradual turn toward the northwest, keeping just west of the CNMI as it heads north.
Tropical Depression 12W could become a tropical storm by Friday morning.
What to expect
Residents of Guam and the Northern Marianas can expect periods of showers, thunderstorms, locally heavy rainfall and strong gusty winds over the next few days.
“In what will be a two-part weather event, a southwest monsoon surge will build in across the Marianas, prolonging winds and rain into the weekend,” an announcement from the National Weather Service stated.
Forecasters warned residents to secure or take down loose and wind-vulnerable items, such as tents, canopies, tarps and trash bins.
The tropical storm watch for Rota, Tinian, Saipan, and their coastal waters, and for Alamagan, Pagan, and Agrihan means tropical storm force winds of 39 mph are possible
Dangerous conditions
A number of weather advisories remain in effect for the Mariana Islands.
A flash flood watch remains in effect for Guam, Rota, Tinian, and Saipan through late Saturday night. Flash flooding caused by excessive rainfall is possible. Rainfall amounts of 6 to 12 inches are possible through Saturday night.
A small craft advisory is in effect for Guam, Rota, Tinian and Saipan coastal waters through 6 a.m. Sunday. Seas of 8 to 12 feet are expected.
A high surf advisory with a high risk of deadly rip currents is in effect for Guam, Rota, Tinian and Saipan until 6 a.m. Sunday. The high risk of rip currents will start on east-facing reefs Thursday morning and shift to south and west-facing reefs late Thursday or early Friday.
A wind advisory is in effect for Guam until 6 a.m. Sunday, with South to southwest winds 20 to 35 mph with gusts up to 50 mph, especially at higher locations, in areas of channeled terrain, and near heavier showers and thunderstorms.
