626
FXPQ50 PGUM 240900
AFDGUM

Area Forecast Discussion
National Weather Service Tiyan GU
700 PM ChST Sat May 24 2025

..Marianas Synopsis...
Light to gentle trades reign over the Marianas. Satellite imagery
indicates just partly cloudy skies over Guam and Rota, and scattered
showers with some thunderstorms in northeastern Saipan waters. The
buoys indicate seas are around 4 feet, complimented by recent
altimetry passes indicating seas of 3 to 5 feet to the west of the
region.

&&

.Discussion...
A mostly calm night is expected at Guam and Rota overnight, meanwhile
Tinian and Saipan may observe some showers moving through as a
trade-wind boundary makes its way across near midnight. No
thunderstorms are expected tonight, but some thunderstorm development
is observed along the northeastern peripheries of the surface trough
with embedded mid-level low moving in near Tinian and Saipan.
Confidence remains low regarding any development near Saipan, but the
forecast may be updated if conditions warrant. Once this feature
exits the region, patchy showers will continue across Tinian and
Saipan due to lingering remnants of a quasi-stationary front
upstream. Meanwhile at Guam and Rota, occasional upticks in low-end
scattered showers are expected throughout the forecast period as a
nearby TUTT helps to continue to enhance local convection.

&&

.Marine...
Benign seas of 3 to 5 feet are expected the next few days, before
gradually falling to 2 to 4 feet around Tuesday, due to the primary
swell weakening. A moderate risk of rip currents remains along east
facing reefs through at least Tuesday. As the primary swell
diminishes, so too will the risk of rip currents along east reefs,
potentially dropping to low as early as Tuesday night.

&&

.Fire weather...
0.01 inches of rain has fallen since midnight. The KBDI remains at
741, which is in the high category due to the sustained winds
remaining below the 20 mph threshold. Showers are not expected to
produce enough rain for the remainder of the night, to prevent the
KBDI from rising. Both winds and relative humidity values look to
remain below Red Flag Warning criteria the next few days.

&&

.Eastern Micronesia...
A couple of weak trade-wind troughs near Pohnpei and Kosrae, and
developing trade-wind convergence near Majuro are generating
scattered showers across the region and affecting Pohnpei, Kosrae,
and Majuro. Thunderstorms have been very isolated and brief across
most of the region, with the exception for the far northern Marshall
islands, just north of Bikini and Rongelap, where the TUTT and a
trade-wind trough are interacting. As the trade-convergence near
Majuro strengthens and shifts west-southwest, it will continue to
produce scattered showers and isolated thunderstorms across Kosrae
and southern Pohnpei state, while, the island of Pohnpei sits on the
northern edge of this feature through Tuesday, these showers may
become isolated at times. Meanwhile, Majuro should see showers become
isolated Sunday night through Monday night as the trade convergence
shifts west-southwest. A trade-wind trough will move cross the Date
Line and into the Marshall Islands, Tuesday. The trough is expected
to shift the showers northward into Majuro and potentially into the
northern Marshall Islands. Then, further increasing showers and the
potential for thunderstorms at Kosrae and Pohnpei around Wednesday
and Thursday as the trough continues westward across the region.

Scatterometer data this afternoon shows gentle to moderate trade
winds across Pohnpei and Kosrae, and moderate to fresh around the
Marshall Islands. Combined seas are currently around 3 to 5 feet
around Pohnpei and Kosrae and 4 to 6 feet around Majuro. The east
swell will slowly build across the region causing seas to build to
between 5 and 7 across the Marshall Islands, and 4 to 6 feet at
Pohnpei and Kosrae.

&&

.Western Micronesia...
A moderate to occasionally deep, albeit disorganized trade-wind
convergence, will continue to bring unsettled weather to Palau and
Yap through at least Sunday night. Heavy showers and some
thunderstorms will continue to pummel Palau tonight, followed by
increasing showers at Yap. A peak in shower and thunderstorm coverage
is expected Sunday at both Palau and Yap, but high uncertainty
remains in the exact timing due to the disorganized nature of
localized convection. Conditions will then steadily improve beginning
Monday, as more familiar moderate trades return. Meanwhile at Chuuk,
patchy showers brought by gentle to moderate trades are expected for
much of the forecast period.

Combined seas of 3 to 5 feet are expected across much of the region
for much of next week, potentially a foot lower near Palau and Yap
(indicated by recent altimetry passes), as trade swell remains
seasonally diminished due to weaker trades upstream.

&&

.GUM WATCHES/WARNINGS/ADVISORIES...
GU...None.
MP...None.
Marianas Waters...None.
&&

$$

Marianas: Bowsher/Montvila
East Micronesia: Schank
West Micronesia: Montvila