Area Forecast Discussion
Issued by NWS Tiyan, Guam
Issued by NWS Tiyan, Guam
930 FXPQ50 PGUM 100816 AFDGUM Area Forecast Discussion National Weather Service Tiyan GU 616 PM ChST Fri Jan 10 2025 .Marianas Synopsis... Moderate diffusive trades prevail in the region, carrying shallow low-level clouds upstream. Tanapag buoy indicates seas are around 6 feet. && .Discussion... Model time heights indicate very little moisture above 850mb over the region, which is complement by recent MIMIC TPW values below 1.30 inches upstream. In addition to the diffusive nature of the trade winds, and the shear line remaining well north of the main islands in the Marianas, mostly pleasant weather with little to no showers expected for much of the forecast period. Saturday night looks to be a good night for stargazing, if conditions remain as expected. && .Marine/Surf... Combined seas of 6 to 7 feet are expected to trickle a foot or two higher in the next few days, as a larger north swell is expected to move into the region by Sunday, coinciding with the arrival of increased trade swell. This will bring combined seas to between 8 and 10 feet, producing sea conditions hazardous to small craft. Seas will briefly ease Monday through Tuesday, followed by a stronger pulse of north swell arriving around midweek. These fluctuating conditions are expected to increase surf heights as well, with potentially hazardous surf along north facing reefs starting Sunday into early next week. During the same time period, a high rip current risk may develop along north and east facing reefs. In the meantime, a moderate risk of rip currents is expected along west, north, and east facing reefs through Saturday night. && .Eastern Micronesia... Satellite shows just patchy showers across southern parts of the region; from over southern Pohnpei State, moving across Kosrae, to near and southeast of Majuro. These patchy areas of showers and convergent trade winds are expected to move only slowly, perhaps farther westward, without much change of intensity. Today`s ASCAT winds show fresh to strong surface winds spreading across Eastern Micronesia from the east-northeast. Other than the patchy showers mentioned above, relatively dry weather is still expected to develop over most of the region. Small Craft and High Surf Advisories remain in effect for Pohnpei, Kosrae and Majuro, and including Coastal Flood Statement for Majuro. Wave models indicate the north swell of about 5 to 7 feet across the Marshall Islands earlier today will subside to 4 to 6 feet tonight, then 3 to 5 feet on Saturday. Hazardous surf of 10 to 12 feet and minor coastal inundation could persist through tonight and Saturday along north facing shores, especially during high tide. && .Western Micronesia... ASCAT analysis shows the Near-Equatorial Trough (NET) in the southwest corner of the region, from EQ141E and extending northwestward to beyond 4N130E. Satellite trends show the feature weakening as moderate convection near Sonsorol dissipated over the course of the day. Across the rest of the region, a moderate to fresh trade-wind pattern exists. Breezy conditions will gradually develop for Chuuk in the coming days as the pressure gradient increases, most notably late weekend and early next week. Expect periods of scattered showers over the next several days as shallow trade-wind troughs move through. Trade-wind troughs moving north of the NET yield slightly better shower coverage for Palau over the next day or two, then the NET shifts even farther southwest. Dominant trade swell, background north swell, and moderate to fresh trade winds will maintain choppy seas across the region. Occasionally strong wind gusts may occur for Chuuk in the coming days, then trade winds are expected to build to moderate to strong by Monday. Seas are also expected to reach hazardous levels of 10 feet by Sunday or Monday with the arrival of north-northwest swell for Yap and Palau and building trade winds and swell. Mariners operating small craft should check for forecast updates as a Small Craft Advisory will likely be issued within the next couple days. Surf may also become elevated along north-facing reefs with an increase in long-period north swell and refracted waves from building ENE trade swell. Model projections do not indicate hazardous surf at this time, but will continue to monitor this in subsequent model runs. && .GUM WATCHES/WARNINGS/ADVISORIES... GU...None. MP...None. Marianas Waters...None. && $$ Marianas: Montvila East Micronesia: Simpson West Micronesia: Cruz