Area Forecast Discussion

Marianas Synopsis

Satellite imagery shows mostly sunny skies, while radar imagery shows a few isolated showers to the south of Guam. Altimetry and buoy data show combined seas of 3 to 4 feet.

Discussion

Time heights show a rather thick dry mid-layer which will inhibit deep convection, meaning any showers that do form will be short lived. Island-induced convection will also be minimal as the winds will be above the threshold for these types of showers to stay on island. Overall, a dry pattern regime of isolated showers are expected through the middle of next week.

Marine

Combined seas are 3 to 4 feet across the region. These seas are expected to fall to 2 to 3 feet over the next few days. Winds are expected to be light to gentle. Overall benign seas are expected through the weekend.

Eastern Micronesia

The models today have shown a slowing trend in the organization of a tropical wave crossing the Date Line this afternoon. This was expected though as the models have been ejecting systems too fast and developing them too quick, with a turn to the north and east too quick as well. As such, the "staggered approach" of using a model blend then tempering-down these rainfall potentials looks like a good approach. As such, the westward progression of scattered showers is also slower. Additionally, this allows what is expected to be a broad, slowly-organizing low-level circulation center closer to Majuro. This was reflected in the wind directions in the forecast.

We thought about using a "standard variable wording" to cover this, but ultimately decided on specifying the light wind direction in an attempt to portray where the loosely-orgaized center may track, as this is where the heaviest rainfall/best potential will likely occur (near the circulation center). With that said, Majuro and portions of the RMI may begin to see these effects by the end of the weekend. Otherwise, the system will continue to track slowly west (versus more northwest like the models suggest). This approach aligns well with how previous systems this year have behaved, as mentioned above.

As for marine conditions, light to gentle winds will continue into early next week, with seas holding in the 3 to 5 foot range.

Western Micronesia

Himawari visible satellite imagery depicts a fairly quiet pattern across the region this afternoon. Scattered showers are seen to the east and south of Palau and Yap Proper, on the edge of a broader band of numerous showers that extends across eastern Yap State and to the south of Weno, Chuuk. Isolated thunderstorms were seen within the developing convection south of Weno, associated with the convergence along a robust surface trough that extends roughly east to west through the area. This trough then curves southwest where it meets a broad surface wave centered over southeast Yap State. Showers look to increase for Palau tonight as this surface wave, and associated convergence, lifts northwest toward the area. Scattered showers and isolated thunderstorms will remain in the forecast for Chuuk tonight with the east-west oriented trough nearby. Periods of scattered showers will continue near Palau through Friday as the area of convergence and unsettled weather crosses the region. A quiet doldrum-like pattern then looks to prevail across much of western Micronesia next week with just light to gentle winds expected, becoming variable at times. This may help to support daytime island convection over the major islands of Palau from time to time. Otherwise, just isolated showers are expected for much of the coming week across the region.

Recent altimetry data shows combined seas around 2 to 4 feet throughout the region. Benign sea conditions are expected to continue throughout the forecast period, with a primary swell out of the northeast to east. Sea heights look to increase by a foot or so in the coming week.

GUM WATCHES / WARNINGS / ADVISORIES

GU...None. MP...None. Marianas Waters...None.