FROM: NWS GUM
AREA: NWS GUM County Warning Area
SENT: 2026-07-28T08:49:00+00:00
Area Forecast Discussion: NWS GUM
000
FXPQ50 PGUM 280849
AFDGUM
Area Forecast Discussion
National Weather Service Tiyan GU
649 PM ChST Tue Jul 28 2026
.Marianas Synopsis…
Light to moderate easterlies prevail across the region. Satellite
imagery and Doppler radar indicate a line of significant
thunderstorms trailing off the coast of Umatac. Buoys show seas are
around 3 feet.
&&
.Discussion…
Remnants of 93W, now a slowly-rotating trough axis, is expected to
continue bringing scattered showers and isolated thunderstorms
overnight. Then, gradual improvement is expected through Wednesday
night as light diffusive southerlies ensue thereafter. As Typhoon
Dolphin (12W) continues to strengthen and pass well northeast of the
region, this will induce a much stronger monsoonal flow across the
Marianas, likely to bring another period of elevated showers and much
stronger winds by next week.
&&
.Marine…
Combined seas of 3 to 5 feet are expected to decrease through
Thursday night, followed by the arrival of an easterly swell
generated by distant Typhoon Dolphin and lingering south-
southwesterly swells. By the weekend, a consistent monsoonal regime
will ensue, potentially introducing sea conditions hazardous to small
craft.
&&
.Tropical Systems…
Typhoon Dolphin is seen to the N of the Marshall Islands, well SE of
Wake Island, centered near 13.3N 171.7E. Dolphin is moving W at 10
mph. Maximum sustained winds are now 85 mph, with tropical storm
force winds extending up to 80 miles from the center. Dolphin is
expected to make a turn toward the WNW, then NW over the next few
days as it continues to strengthen. Latest guidance shows Dolphin
could go through rapid intensification, possibly becoming a super
typhoon Thursday night or Friday. Dolphin is not expected to directly
impact Micronesia or the Marianas, though it is eventually expected
to move through somewhere between the far northern CNMI and Wake
Island. Residents of Wake Island need to monitor the progression of
Dolphin, as it is expected to strengthen into a significant typhoon
over the next couple of days as it passes S of Wake Island. If
Dolphin makes a more NW turn toward Wake Island than expected, it
could become a very dangerous situation for the island.
For more information on TS Dolphin, please refer to bulletins by the
Joint Typhoon Warning Center under WMO header WTPN31 PGTW and by the
National Weather Service under WMO header WTPQ31 PGUM.
&&
.Eastern Micronesia…
The main feature affecting eastern Micronesia continues to be the
monsoon trough. Westerly winds are seen across the region, with
increased moisture and convergence south of the monsoon trough
creating areas of scattered showers and isolated thunderstorms,
mainly near Pohnpei and Kosrae. Convection does look to increase
over the next few hours at all three locations as the monsoon flow
strengthens south of TS Dolphin. With Dolphin likely to go through
some rapid intensification some time over the next couple of days,
this is expected to increase the monsoon flow over eastern
Micronesia, resulting in more convection across the region. An
overall very unsettled pattern is expected through the end of the
week at Pohnpei and Kosrae, and through the weekend at Majuro.
Although seas will not be too impressive, they could still be choppy
at Pohnpei and Majuro due to moderate to fresh winds producing wind
waves of 4 feet.
&&
.Western Micronesia…
An unsettled monsoon pattern persists across much of Micronesia. The
western portion of the monsoon trough remains anchored just north of
Palau and Yap, with a broad area of convergent, moderate westerlies
to southwesterlies producing scattered showers across the islands,
and numerous showers just farther east across much of central Yap
State. Surface observations at Palau showed wind gusts up to 25 kts,
associated with some of the heavier passing showers. Far to the east,
showers are patchy across Chuuk State, but satellite and model trends
point to increasing showers near Weno this evening, and especially
late overnight as convergence builds across the area. The western
half of the monsoon trough will be semi-stationary north of Yap and
Palau through the next few days, while the eastern half gradually
shifts north, with the expected northwest movement of Typhoon
Dolphin. This will take the convergence and showers farther north of
Chuuk, leading to drier conditions there this weekend and early next
week. Meanwhile, at least scattered showers will continue at Palau
and Yap throughout the week, becoming locally heavy at times, and
shower coverage will shift slightly farther north over Yap Proper
late in the week.
Benign marine conditions continue, but seas will become increasingly
choppy late in the week for Chuuk as the west to southwest monsoon
swell builds, wind waves increase, and a long-period swell arrives
from the northeast, emanating from TY Dolphin. This could bring
challenges to small craft through the weekend, as well as increasing
surf along west, north, and east-facing reefs. The magnitude of these
impacts are uncertain, and will depend in part on the movement and
development of Dolphin far to the northeast. In the meantime,
altimetry and Yap buoy data show combined seas between 2 and 4 feet
near Yap and Palau, and between 3 and 5 feet near Chuuk.
&&
.GUM WATCHES/WARNINGS/ADVISORIES…
GU…None.
MP…None.
Marianas Waters…None.
&&
$$
Marianas: Montvila
East Micronesia/Tropical Systems: Kleeschulte
West Micronesia: DeCou
Alert Expiration: 2026-07-28T16:49:00+00:00
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