861
FXPQ50 PGUM 032018
AFDGUM

Area Forecast Discussion
National Weather Service Tiyan GU
618 AM ChST Wed Nov 4 2026

.Marianas Update...
Satellite and radar imagery depict widely scattered showers moving
west-northwest across the coastal waters, associated with a subtle
trade-wind trough moving into the Marianas this morning. Showers were
increased slightly in the forecast this morning, but are expected to
decrease to isolated by noon. Low-end scattered showers look to build
after midnight tonight as the next trade-wind trough moves in, but
this increase in showers will mainly be for the CNMI and northern
coastal waters of Guam. A fairly dry regime will continue for the
next few days before a robust trade-wind trough or weak disturbance
moves across the Marianas, around Friday night through Saturday.

&&

.Tropical Systems Update...
Typhoon In-fa (30W) strengthened slightly overnight as it crawled
northwestward, nearly stationary to the west-southwest of Iwo To. At
2 AM ChST, it was located near 23.6N 138.7E, or about 805 miles
north-northwest of Guam. Maximum sustained winds are now 85 mph and
In-fa remains a Category 1 typhoon, but it may briefly strengthen to
Category 2 tonight after it passes to the west of Iwo To, before
weakening Thursday.

For more information on Typhoon In-fa, please refer to bulletins
from the Joint Typhoon Warning Center under WMO header WTPN31 PGTW
and from the National Weather Service under WMO header WTPQ31 PGUM.

&&

.Eastern Micronesia Update...
A fairly unsettled regime continues. Satellite imagery this morning
shows bands of scattered to numerous showers building along the broad
monsoon-like trough that extends across the region, especially near
and south of Pohnpei within an area of enhanced convergence. So,
showers were increased in Pohnpei`s forecast for today with isolated
thunderstorms still expected. Otherwise, little change was made in
the forecast package.

&&

.Western Micronesia Update...
Little change was made to the forecast package overnight. An
elongated circulation remains southwest of Chuuk within the broad
monsoon-like near-equatorial trough across the region. Most of the
showers and thunderstorms are focused along its southern periphery
where convergence is stronger, and Chuuk remains fairly dry.
Conditions also remained mostly dry for Palau and Yap overnight. The
High Surf Advisory for north facing reefs of Palau and Yap was
extended through 5 PM ChST this afternoon, as pulses of long-period
swell from distant, nearly-stationary Typhoon In-fa continue to move
through the region.

&&

.Prev discussion... /issued 516 PM ChST Tue Nov 3 2026/

Marianas Synopsis...
Radar and visible satellite imagery show isolated, light trade-wind
showers, with highest coverage around Guam and Rota. Models and
observations show combined seas of 5 to 6 feet.

Discussion...
Showers are expected to remain largely isolated through Friday.
Occasional patches of weak, scattered trade-wind showers will be
possible, particularly in the late night hours over the coastal
waters. Gentle winds tonight will become gentle to moderate Wednesday
and hold steady before possibly decreasing with the arrival of a
trough Friday night. Models indicate this trough will move into or
just north of the Marianas by Friday. So the location remains
uncertain, however, confidence is high enough to put scattered
showers in the forecast for Tinian and Saipan, and isolated
thunderstorms for all islands. By Saturday night, the isolated trade-
wind shower regime will likely return.

Marine...
Gentle to moderate winds are expected through Friday. Combined seas
of 5 to 6 ft will now remain steady, before possibly increasing
slightly in the latter half of the week due to an increasing trade-
wind swell. There is a moderate risk of rip currents along north,
east, and west-facing reefs. Swells consist of a diminishing
northwest swell from distant Typhoon In-fa and an east-northeast
trade-wind swell. Scattered showers will be possible after midnight
tonight and Wednesday night. A trough may move into the Marianas
Friday night and Saturday, possibly bringing more scattered showers
and isolated thunderstorms. Therefore, a moderate risk of lightning
is possible Friday night and Saturday.

Tropical Systems...
Typhoon In-fa continues to churn across the open Pacific while
retaining its symmetry on visible imager. The 1 PM ChST position has
In-fa at 23.2N 139.1E, located 175 miles southwest of Iwo To, moving
west (280 degrees) at 7 mph. However, the latest visible imagery
suggests it may have made that northward turn. Typhoon force winds
extend outward from the center up to 35 miles, mainly on the northern
side. Tropical storm force winds extend outward from the center up
to 115 miles.

For more information please refer to bulletins from the Joint
Typhoon Warning Center under WMO header WTPN31 PGTW and from the
National Weather Service under WMO header WTPQ31 PGUM.

Eastern Micronesia...
The main forecast challenge continues to be rainfall potential,
mainly at Kosrae. Currently, the monsoon trough is in an east-west
orientation near 4N, which is a little further south than yesterday.
This is far enough south to only produce isolated showers for most
of the time across Pohnpei, Kosrae, and Majuro. Although, if it ends
up lifting slightly north, rainfall coverage could increase some for
Kosrae. Looking ahead, the trough looks to weaken, which in turn
weakens surface convergence, reinforcing the isolated shower
approach.

For our mariners, look seas of 4 to 6 feet to continue, possibly
dropping a foot later in the week. Winds will be light to gentle
area-wide.

Western Micronesia...
A monsoon-like, near-equatorial trough remains stretched out across
the region, producing patchy showers across Palau and Chuuk. Active
weather continues on the southern side of the trough, across open
waters south of Yap State and western Chuuk State. Drier air lingers
across Yap, so fair weather is expected to persist through the week.
For Palau and Chuuk, overall weather pattern remains fairly quiet
and mainly isolated showers are expected through Saturday, then a
slight uptick in showers is possible Sunday due to an increase in
trade-wind convergence.

Combined seas are 4 to 6 feet, with seas increasing to 5 to 7 ft at
Yap and Palau from north to northeast swell emanating from distant
Typhoon In-fa. Hazardous surf of 7 to 9 feet continue along north-
facing reefs of Yap and Palau and a High Surf Advisory remains in
effect through late tonight, although elevated surf may still persist
through Wednesday as the pulse of long-period swell diminishes.
Benign seas and surf continue at Chuuk, comprised of a dominant
northeast swell and diminishing northwest swell. Combined seas of 3
to 5 feet peak up to 6 feet around Thursday night from a brief
increase in northeast swell.

&&

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

$$


Marianas/East and West Micronesia/Tropical Update: DeCou
Marianas: Ogle
East Micronesia: Kennedy/Stanko
West Micronesia: Cruz
Tropical: Doll