SAIPAN — A tropical disturbance, Invest 99W, has been upgraded to a medium chance of development by the Joint Typhoon Warning Center and is expected to be classified as a tropical depression on Wednesday, but the system does not pose a threat to the Marianas, the National Weather Service in Tiyan, Guam, said in its weekly regional weather outlook Tuesday.
The disturbance is currently located near 8.4N 138.8E, just east of Yap State, after tracking slowly westward across the area in recent days, NWS Guam said. The system is expected to lift north-northwestward into the Philippine Sea as it continues to develop, taking it well west of Guam and the CNMI.
“99W does not pose a threat to Guam or the CNMI, and will keep well to the west,” the outlook, prepared by Warning Coordination Meteorologist Landon Aydlett, said.
Despite the disturbance staying west of the region, the Marianas will remain under its influence this week. Moderate to fresh trade winds converging into the eastern periphery of the broader wind field around 99W will keep a showery pattern in place across Saipan, Tinian, and Rota, NWS Guam said.
Combined seas of 3 to 5 feet around the Marianas are expected to build to around 6 to 8 feet by the end of the week, as a long-period north swell and a southwest swell reach the region.
Conditions will be far more severe in western Micronesia, where Yap and Palau are bracing for a wet pattern with gusty southwest to west winds, locally heavy rainfall, and choppy seas as 99W moves through and northwest of the area, the outlook said. A Special Weather Statement has been issued for western Micronesia, including Palau, Yap, and Chuuk, NWS Guam said.
Farther east, variable winds and a few showers are present near Chuuk, while the Intertropical Convergence Zone is generating showers and thunderstorms near Pohnpei and Kosrae. Drier weather prevails near and north of Majuro.
NWS Guam said there are no other suspect areas for tropical cyclone development across its Area of Responsibility through the weekend.
The agency also said no drought concerns exist across the region at this time, though a drier trend is anticipated across Palau and Yap State into mid-June, with below-normal rainfall expected for those areas.
