Area Forecast Discussion

Marianas Synopsis

Satellite and radar imagery show partly cloudy skies and isolated showers across the region. Altimetry and buoy data show combined seas between 6 and 8 feet.

Discussion

A few changes were made to the short term forecast. The main one was to significantly reduce PoPs over the next few days. Guidance has backed off on scattered showers, shifting the bulk of showers and thunderstorms south of the Marianas. Low end (30%) scattered showers remain in the forecast for Monday night, but trends will need to be monitored as the forecast could continue to decrease in confidence. A moisture surge is looking to push into the Marianas late this week. This surge in moisture looks to be associated with a sharp surface trough that looks to approach the region on Saturday.

Marine

Combined seas are between 6 and 8 feet and are expected to persist through the middle of the week. A High Risk for Rip Currents is in effect for east facing reefs until Tuesday afternoon. A brief lull in rip currents of 9 feet is forecasted on Monday before rising to 9 feet Monday night and into Tuesday. Seas look to fall towards the end of the week with combined seas 4 to 6 feet expected on Friday.

Eastern Micronesia

An unsettled, disorganized pattern prevails across eastern Micronesia. Himawari visible satellite imagery this afternoon shows moderate to deep convection developing near and east of Pohnpei, and to the north of Kosrae, associated with convergence along a broad trade-wind trough extending south through the region. To the east, cloud cover is patchy and widespread, mainly from the central RMI northward, and along a trade-wind trough approaching from the east, located near the Date Line. Isolated to scattered showers prevail across much of the region, with numerous showers seen along and east of the Date Line.

Model guidance depicts an unsettled pattern continuing through much of the week as trade-wind troughs propagate westward across the area, along a developing Intertropical Convergence Zone (ITCZ). The ITCZ becomes better-organized Monday night and Tuesday as it extends west of Kosrae and Pohnpei, where a more robust disturbance begins to form. Meanwhile,an upper-level low, currently centered north of the Marshalls, will meander westward just north of the region, interacting with these features at the surface to develop showers and thunderstorms across the area. Showers are expected to become numerous for Pohnpei Monday night, with locally heavy rainfall possible, with at least scattered showers expected through the rest of the forecast period. Showers will remain scattered for much of this week for Kosrae and Majuro as well, as trade-wind troughs and a fragmented ITCZ maintain a wetter pattern, potentially with support from upper-level troughing.

Benign marine conditions are expected through the week. Latest altimetry data indicates combined seas between 5 and 7 feet across the region, peaking near 8 feet northeast of the RMI. Models depict a gradual relaxation of the east to northeast trade swell throughout the week, allowing seas to gradually decrease by a foot or two over the next several days.

Western Micronesia

The main weather makers for the regions is rather large band of convergence spanning across most of the regions. Most of the showers are from north of Chuuk to south of Palau. Within this band scattered to numerous showers are expected and some may be locally heavy at times. For now this is mainly effecting the outer islands of Yap state, however as time marches on this feature will move westward bringing showers to both Yap and Palau as early as Monday. Current model estimations suggest this feature will bring showers to both Yap and Palau through the end of the week.

Meanwhile in Chuuk as of this writing, showers appear to be fairly minimal. However, that is expected to change as shower are expected to fill in tonight. Then over the week, the showers and troughs that are effecting pohnpei now are expected to move into Weno making for a fairly wet week.

Benign marine conditions continue through much of the upcoming week. Altimetry shows 2 to 4 foot seas at Palau and Yap, increasing to 4 to 6 foot at Chuuk. Trade-wind swell continues to build into the region, and is expected to increase seas to 4 to 6 feet at Yap and slightly increase seas at Palau to 3 to 4 feet Monday and Monday night. Afterwards, trade winds and swell subside, allowing seas to decrease back down to 3 to 5 feet towards the second half of the week.

GUM WATCHES / WARNINGS / ADVISORIES

GU...High Rip Current Risk through Tuesday afternoon for GUZ001.

MP...High Rip Current Risk through Tuesday afternoon for MPZ001>003.

Marianas Waters...None.