418
FXPQ50 PGUM 052006
AFDGUM

Area Forecast Discussion
National Weather Service Tiyan GU
606 AM ChST Sat Dec 6 2025

.Marianas Update...
A dry trade-wind pattern extends across the Marianas with Guam`s
Doppler radar showing only spotty trade showers this morning. Winds
are expected to be around 10 to 15 mph over the next few days. Buoy
data around Guam shows seas are between 5 and 6 feet, with altimetry
data showing seas increase to between 6 and 8 feet north of Saipan
as a pulse of northerly swell starts to move into the region. Seas
are expected will gradually subside a foot Sunday through Monday
before the next pulse comes in to bring seas back up to 6 to 8 feet.
Gentle to moderate wind will continue across the coastal waters
through Sunday before slightly subsiding Sunday night. Surf will be
elevated along north facing reefs with a moderate risk of rip
currents along north and east facing reefs the next few days, but
surf along north facing reefs is not expected to build to hazardous
levels of 9 feet.

&&

.Eastern Micronesia Update...
Satellite imagery shows dry weather across Pohnpei and Majuro, but a
cluster of numerous locally heavy showers and isolated thunderstorms
currently extends over Kosrae. This area of convection is being
generated by convergent flow and a trough extending from a buffer
circulation near 1N162E, and supported by upper-level troughing
extending northeast from near Pohnpei and into the northern Marshall
Islands. An preliminary reports from an automated rain gauge on
Kosrae suggest around 5 inches of rain has fallen at Kosrae since
midnight. Model guidance suggest the buffer circulation and trough
will shift westward, allowing the heavier convection to shift west
and south of Kosrae this afternoon, but scattered showers are
expected to at Kosrae through Sunday, while the potential for
isolated thunderstorms is expected to decrease this evening. For
Pohnpei and Majuro, a dry trade-wind pattern is expected across both
locations the next few days, while weak convergence may bring a brief
period of scattered showers to Pohnpei Sunday.

A Small Craft Advisory (SCA) remains in effect for Majuro for trade
winds of 15 to 25 kt along with a building northeast swell pushing
seas up around 8 to 12 feet. This elevated northeast swell, along
with a secondary long-period north swell, is also producing hazardous
surf waves 10 to 13 feet along north and east facing reefs, with the
High Surf Advisory (HSA) in effect through Sunday afternoon. The
Coastal Flood Advisory (CFA) is also still in effect through Sunday
afternoon as the combination of the King Tide cycle and swells will
increase the risk for moderate coastal flooding. The HSA is still in
effect for east facing reefs Kosrae for surf up to 8 feet through
Sunday afternoon. Pohnpei`s buoy shows seas are around 6 to 7 feet
with the primary swell being the elevated northeast swell, so surf is
below hazardous levels of 9 feet along north facing reefs. The GFS
and ECMWF wave models show another pulse of northerly swell moving
into the region around Sunday and around the same time it looks like
the northeast swell will also build slightly and together this may
build surf up to 9 feet along north facing reefs of Pohnpei and
Kosrae extending the HSA to north facing reefs at both locations
Sunday. The GFS shows a quick spike in surf and sea heights Sunday
that then starts to subside Sunday night into Monday, while the ECMWF
shows a very gradual decrease. If the ECMWF timing is correct, then
the advisories mentioned above may have to be extended beyond Sunday
afternoon.

&&

.Western Micronesia Update...
Satellite imagery this morning shows partly cloudy skies with spotty
showers across Chuuk, while mostly cloudy skies with scattered
showers and isolated thunderstorms are developing around Palau and
Yap due convergence along the Near-Equatorial Trough (NET). As the
NET shift westward, Yap should see showers and the potential for
thunderstorms decrease this afternoon, but scattered showers will
likely linger through the day at Palau before drier weather moves in
tonight. Model guidance and satellite trends favor a dry pattern
across the region through at least the middle of next week.

The main concern over the next few days will be the coastal and
marine conditions. For Chuuk, the north swell there continues to
subside, and limited altimetry data seas are around 5 to 7 feet,
down from the 6 to 8 feet yesterday, however, an elevated trade-wind
swell is expected to build at Chuuk around Sunday, likely pushing
seas back up to 8 feet. Will have to monitor if surf will reach
hazardous levels of 9 feet along north facing reefs at Chuuk Sunday,
but currently models suggest surf will be just below that threshold.
Moderate coastal inundation of just over 1 foot along north and east
facing reefs is still possible due to the King Tide cycle today. The
high tides will begin to slowly fall after today so unless data
supports extending the Coastal Flood Advisory, it may be allowed to
expire this afternoon. For Yap and Palau, another round of north
swell is now moving into the region. The north swell, combined with
the King Tide cycle is expected to produce minor coastal inundation
along north facing reefs. The north swell is expected peak at around
6 to 7 feet tonight, resulting in hazardous surf along north facing
reefs as well. Therefore, a High Surf Advisory (HSA) and Coastal
Flood Statement (CFS) remain in effect for north facing reefs of Yap
and Palau. Tides and swell should decrease enough by Sunday night
for the inundation and hazardous surf to end at Palau. Yap will see
higher swell a bit longer, so both the HSA and CFC will remain in
effect until early Monday morning.

&&

.Prev discussion... /issued 620 PM ChST Fri Dec 5 2025/

Marianas Synopsis...
Satellite imagery shows mostly cloudy skies for Guam and mostly
sunny skies over the CNMI. Radar imagery shows scattered showers and
isolated thunderstorms over Guam and Guam coastal waters. Altimetry
show seas of 6 to 7 feet, while buoy data shows 4 to 6 foot sea
heights.

Discussion...
Scattered showers and isolated thunderstorms over Guam panned out.
These showers are expected to diminish as through the evening.
Pleasant weather is in store for all of the Marianas through most of
next week. Winds are expected to be 10 to 15 mph providing a nice
breeze to compliment the pleasant weather.

Marine...
The seas and swells are expected to be in a bit of flux over the
next week as pulses from a distant mid-latitude feature ripple
through the region. Seas are expected to bounce between 5 to 7 and 6
to 8 over the next several days. This will firmly place the risk of
rip currents along north and east facing reefs in the moderate
category. While these sea conditions will be elevated, they are
expected to remain below Small Craft Advisory (SCA) and High Surf
Advisory (HSA) conditions. However, seas are expected to be choppy.

Eastern Micronesia...
Satellite observations show isolated showers over eastern
Micronesia. Altimetry and buoy date show combined seas between 6 and
9 feet across the region.

Quiet conditions are in place across the island zones with only
Kosrae expected to see scattered showers starting late tonight and
continuing through the next few days. Otherwise, the axis of shower
activity has shifted south of Pohnpei and Majuro and isolated
showers are forecast through the period. Long range guidance beyond
seven days shows little change with this pattern, with the focus of
convection remaining further south.

The marine forecast continues to be the main talking point for
eastern Micronesia. Combined seas are currently between 6 and 9 feet
across the region, but will continue to rise over the coming days.
This afternoon`s ASCAT pass showed 22 to 25 kt winds entering the
northern portions of the Marshall Islands. These winds are
forecast to shift southward tonight and a Small Craft Advisory was
issued for Majuro through Sunday afternoon. Large breaking waves of
10 to 13 feet will also lead to hazardous surf for north and east
facing reefs of Majuro beginning Saturday morning and continue until
Sunday afternoon. The Coastal Flood Advisory was also extended into
Sunday afternoon.

The High Surf Advisory was cancelled for Pohnpei and north facing
reefs of Kosrae. Confidence is high enough that surf will remain
below the 9 foot threshold for at least 24 hours. The High Surf
Advisory was extended for east facing reefs of Kosrae due to the
criteria being 8 feet. Surf does look to become hazardous again for
north facing reefs of Pohnpei and Kosrae on Sunday or Sunday night
and a High Surf Advisory will likely need to be re-issued for those
reefs with tomorrow`s package.

Western Micronesia...
Latest satellite data shows partly cloudy skies with spotty showers
across Palau and Chuuk. Yap has mostly cloudy skies with isolated
showers, however, scattered showers and isolated thunderstorms are
seen to the east of Yap Proper. Altimetry shows seas between 4 and 7
feet for Yap and Palau, with higher seas north, and 6 to 8 feet for
Chuuk.

A mostly dry pattern is now in place across western Micronesia. The
only exception is Yap. Only isolated showers are seen at Yap right
now, however, a band of scattered showers and isolated thunderstorms
is approaching from the east. This convection is associated with a
weak band of convergence north of the Near-Equatorial Trough (NET).
The NET continues to weaken as it drifts west and this will allow
the band of convergence to move across Yap tonight as it pushes
toward the northwest. By Saturday morning, expect to see the dry
pattern set up across Yap State. Model guidance and satellite trends
favor a dry pattern across the region through at least the middle of
next week.

The main concern over the next few days is the coastal and marine
forecast. For Chuuk, the north swell there continues to subside,
however, a large trade-wind swell is building into the state. This
will maintain moderate coastal inundation of just over 1 foot along
north and east facing reefs due to the King Tide cycle. Later in the
weekend and early next week, the high tides will begin to fall and
coastal flooding will no longer be a problem. For Yap and Palau,
another round of north swell is now moving into the region. The north
swell, combined with the King Tide cycle is expected to produce
minor coastal inundation along north facing reefs Saturday morning.
The north swell is expected to reach 6 to 7 feet, resulting in
hazardous surf along north facing reefs as well. Therefore, a High
Surf Advisory (HSA) and Coastal Flood Statement (CFS) were issued for
north facing reefs of Yap and Palau. Tides and swell should decrease
enough by Sunday night for the inundation and hazardous surf to end
at Palau. Yap will see higher swell a bit longer, so both the HSA and
CFS will remain in effect until early Monday morning.

&&

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

$$


Marianas/East and West Micronesia Update: Schank
Marianas: Bowsher
East Micronesia: Williams
West Micronesia: Kleeschulte