textproduct: Tiyan

Marianas Update

Overall the forecast for the Marianas was in good shape, and no changes were made. The advisories will almost certainly have to be extended. Any reprieve will be too short to cancel or expire them. Left that for the day shift to decide how far they should be extended as this is my first night so I had no continuity to work with.

Marine

Ipan buoy is showing 7 to 8 foot seas from the northeast. Northeast is a fairly sheltered direction for Ipan buoy, so the real heights are probably higher. Gradient wind of 26 knots also supports gusts of 25 knots, and the forecast has it going up to 30 knots later, so overall the advisory is looking good, as long as it gets extended.

Eastern Micronesia Update

The forecast for Eastern Micronesia was in good shape. Just tweaked the clouds higher at Pohnpei and the daytime temperatures lower, accordingly. The forecasts for Kosrae and Majuro looked to be on track as they were. The ITCZ will be the big influence here the next few days.

Western Micronesia Update

Western Micronesia was looking just fine and no changes were needed. A Tropical Disturbance will reach Yap Monday and Koror Monday night, primarily it will just be rain, with maybe breezy winds. Being close to the ITCZ, Chuuk should have scattered showers through Tuesday then could dry out a bit Wednesday and Thursday.

Prev discussion

/issued 547 PM ChST Sat Mar 21 2026/

Marianas Synopsis... Moderate to fresh northeast winds and isolated to scattered showers prevail across the region this afternoon. A trade-wind trough that moved through today is now west of the region. Radar observations show scattered showers linger across western waters of Guam and Rota and are expected to move out of coastal waters by late tonight. A Small Craft Advisory remains in effect through Sunday afternoon for seas of 7 to 10 feet. A High Surf Advisory for north-facing reefs and a high risk of rip currents along north- and east-facing reefs remain in effect through Sunday afternoon as well.

Discussion... After scattered showers in the wake of a trade-wind trough moves west of coastal waters, moderate to strong northeast winds and isolated showers are expected through Sunday night. A weak circulation in southern Chuuk State is producing a broad area of showers well to the southeast of the Marianas. Showers along the northern periphery of this disturbance is expected to bring an increase in showers Monday through Wednesday, with a slightly higher shower coverage and thunderstorm potential for Guam and Rota. As this disturbance passes well to the south, an area of high pressure pushes eastward off the coast of Japan, tightening the pressure gradient across the Marianas. This will result in breezier conditions through Monday night or Tuesday.

Marine/Surf... Elevated northeast to east swell and wind waves, and long-period north to northeast swell continues to produce hazardous seas up to 10 feet within the eastern Marianas coastal waters, with 7 to 9 feet expected west of the islands. Combined seas may briefly diminish around Sunday night, increasing once more through Monday as a trade-wind surge increases northeast swell and wind waves. Winds will be moderate to fresh out of the northeast to east, briefly becoming moderate to strong Monday and Monday night, then gradually diminishing to light to gentle late week. An extension or another issuance of a Small Craft Advisory will likely be needed for hazardous conditions for Monday and Monday night. Hazardous surf along north facing reefs and a high risk of rip currents along north and east facing reefs continues through at least Sunday afternoon. Swells, surf, and rip current risk will then briefly diminish, although the increase in northeast to east trade-wind swell may increase the rip risk along east-facing reefs back up to high around Monday night. A moderate risk of rip currents will continue along west and south facing reefs through tonight, before rip risk along west reefs decreases to low for Sunday.

Eastern Micronesia... The forecast remains in great shape with minimal changes needed to the entire forecast, mainly to adjust temps upward at Pohnpei and Kosrae, as both hit 90 today. Majuro had a high of 88, but convective debris may help temper afternoon highs tomorrow. An outflow boundary pushing south will focus increased convective development. As such, we increased rainfall probabilities to 50 percent. We contemplated going with higher potential than that, but questions as to how long convection will develop overnight remained, so 50 percent seemed like a good compromise. Otherwise, remaining changes to the forecast were cosmetic (minor).

As for marine conditions, elevated seas at Pohnpei and high surf at Pohnpei and Kosrae remain a concern, as do inundation concerns at Majuro. With that said, seas and surf will decrease early next week, with light to gentle winds prevailing.

Western Micronesia... The latest satellite imagery shows partly cloudy skies with spotty showers for Palau, Yap and Chuuk this afternoon. Altimetry shows seas of 7 to 8 feet near Weno, with 9 foot seas north of Fananu. Seas of 5 to 7 feet are seen near Palau and Yap, with 8 foot seas a little farther north.

A weak circulation remains the focus for the forecast across western Micronesia for the next several days. The circulation has slowed its westward progression a bit and the model guidance has picked up on this. Based on guidance along with satellite trends, kept isolated showers for the evening at Weno, with increasing convection moving in from the east as the circulation drifts west-northwest. The slow movement of this feature looks to maintain scattered showers across Weno for the next few days as it progresses toward Yap and Palau. Yap Proper will see increased convection around Monday as the circulation moves toward the island and pulls the weak Near- Equatorial Trough (NET) a bit farther north. As the system progresses, it looks to spread convection into Palau Monday night. This overall unsettled pattern then looks to continue at Yap and Palau through at least the middle of next week. For Weno, a drier pattern is expected to move into Chuuk around midweek.

The marine forecast is progressing as expected. Seas continue to slowly subside, with the north to northeast swell now down enough for surf to fall below hazardous levels at Yap. However, surf will remain elevated, hovering just below hazardous levels along north facing reefs through tonight. For Palau and Chuuk, mostly light to gentle winds are expected through the coming week. At Yap, gentle to moderate winds will continue through most of next week, with occasional fresh winds possible early in the week.

GUM WATCHES/WARNINGS/ADVISORIES

GU...High Rip Current Risk until 4 PM ChST this afternoon for GUZ001.

High Surf Advisory until 4 PM ChST this afternoon for GUZ001.

MP...High Rip Current Risk until 4 PM ChST this afternoon for MPZ001>003.

High Surf Advisory until 4 PM ChST this afternoon for MPZ001>003.

Marianas Waters...Small Craft Advisory until 5 PM ChST this afternoon for PMZ151>154.