085
FXPQ50 PGUM 071958
AFDGUM

Area Forecast Discussion
National Weather Service Tiyan GU
558 AM ChST Sat Feb 8 2025

.Marianas Update...
A shear line lingering over Tinian and Saipan today and will slowly
drift south over Guam and Rota the next couple of days, with
scattered showers expected. Winds will increase behind the shear line
and will become breezy at times early to mid next week.

Seas continue to subside and will be 6 to 8 feet this weekend.
Another large northerly swell arrives by late Sunday night into
Monday morning and seas are expected to become hazardous to small
craft. Gentle to moderate winds increase to moderate to fresh by
tonight for Tinian and Saipan and by Sunday night for Guam and Rota.
Winds look to increase further and could also become hazardous to
small craft by around Tuesday.

Hazardous surf and a high risk of rip currents will continue along
north facing reefs through this afternoon, with a moderate risk of
rip currents starting tonight. A moderate risk of rip currents may
remain along east and west facing reefs through the weekend.
Increasing surf along west, north, and east facing reefs as another
pulse of significant north swell makes its way across the region
early next week.

&&

.Fire weather...
The Guam airport received only 0.01 inches of rain yesterday,
allowing the KBDI to rise to 558, which is still in the high
category. A shear line is anticipated to move across Guam into early
next week, bringing an increased potential for showers and a wetting
rain. Winds are also expected to increase early next week behind the
shear line.

&&

.Eastern Micronesia Update...
The ITCZ remains in a weakened state this morning with the heaviest
showers located southeast of Kosrae, while light to moderate showers
extend from Chuuk, through the coastal waters of Pohnpei and Kosrae,
and to the south and southeast of Majuro, extending over islands
such as Jaluit and nearby atolls. The main short-term change to the
forecast was to increase cloud cover and showers at Majuro around
noon since the scattered showers southeast of Majuro have been
slowly lifting northwest overnight. Satellite altimetry still shows
sea around 10 feet just east of Majuro, driven by the elevated trade
swell, so continued the Small Craft Advisory for Majuro through
early Sunday morning, while seas remain around 6 to 8 feet at Pohnpei
and Kosrae. This trade swell does weaken near Kosrae and Pohnpei,
but it still strong enough to continue to High Surf Advisory for
Kosrae through at least early Sunday morning with surf up to 8 feet.

&&

.Western Micronesia Update...
Scattered showers and isolated thunderstorms are moving through
Chuuk this morning as a series of weak troughs ahead of the ITCZ are
drifting through. Over by Palau and Yap most of the showers and
thunderstorms remain just south of the coastal waters of Palau, along
the NET that extends from south of Palau and westward through the
Phillipines. Altimetry and buoy data has shown a steady decrease in
sea heights overnight around Yap and Palau, so the High Surf
Advisory and Small Craft Advisory for Palau and Yap were allowed to
expire this morning.

The CIMMS MIMIC TPW satellite product shows some drier air just
north of Chuuk and it looks to be slowly mixing in, so introduced
showers becoming isolated this afternoon at Chuuk, but kept scattered
showers for tonight as models have the moisture moving back in as the
ITCZ in eastern Micronesia nudges into eastern Chuuk State. Showers
along the trough that was in eastern Yap State have diminished
overnight and the convection along the NET trough has been slow to
lift up into Palau. Given this trend, delayed scattered showers and
isolated thunderstorms at both Palau and Yap to the afternoon, and
decreased the chance of showers at Yap from 40 percent to 30 percent.
Kept the chance of showers of 50 percent for the main islands of
Palau as scattered showers continue to develop just south of Palau
and it would just take a slight shift northward to bring these
showers to the main islands of Palau. Seas across the region have
stabilized around 6 to 8 feet as the north swell that was affecting
Yap and Palau has diminished. Another northerly swell event looks to
impact western Micronesia early next week. This may bring another
round of hazardous conditions for small craft and hazardous surf to
Palau and Yap.

&&

.Prev discussion... /issued 521 PM ChST Fri Feb 7 2025/

Marianas Synopsis...
Satellite shows scattered showers and mostly cloudy skies across
Tinian and Saipan, associated with a shear line in the region.
Partly cloudy skies exists south of this boundary, over Guam and
Rota. Buoys indicate seas have decreased to 7 to 9 feet.

Discussion...
A shear line divides the region`s weather conditions over the next
few days. This feature is currently over Tinian and Saipan, expected
to create scattered showers through Sunday. Guam and Rota can expect
fair weather tonight and most of the weekend, before the shear line
starts to shift south. This feature is expected to gradually weaken,
but is still expected to bring scattered showers to Guam and Rota
Sunday night through Monday night.

Marine/Surf...
A High surf Advisory and a high risk of rip currents remain in
effect through tonight. The Small Craft Advisory was cancelled due to
buoy data indicating seas have fallen to 7 to 9 feet and are
expected to further decrease to 6 to 8 feet this weekend. However,
seas look to build back up to hazardous levels when another pulse of
north swell arrives by Monday. Gentle to moderate winds increase to
moderate to fresh starting at Tinian and Saipan over the weekend and
for Guam and Rota by Monday.

Eastern Micronesia...
The Inter-Tropical Convergence Zone is much weaker than was
previously expected, resulting in a decrease in shower coverage
across the region. Eastern Micronesia still looks to continue in a
moist pattern, however, showers look to remain scattered throughout
the forecast with numerous showers no longer expected. There will be
short periods of deep convection as weak trade-wind troughs move
through, though thunderstorms look to remain very isolated. Kosrae
and Majuro can expect a drier trade-wind pattern to return around the
middle of next week.

Latest altimetry shows seas remaining around 10 feet across the
Marshalls, just east of Majuro. Strong gusts are expected to continue
as well. Based on this, extended the Small Craft Advisory for Majuro
for another 24 hours. For Kosrae, trade swell will remain high enough
to maintain hazardous surf along east facing reefs through at least
Sunday night. Latest WaveWatch guidance indicates that the swell
could remain high enough to produce surf of up to 8 feet a little
longer, so the High Surf Advisory may need to be extended. Otherwise,
expect seas to remain around 6 to 8 feet for Pohnpei and Kosrae
through the weekend. Moderate to fresh winds will decrease over the
weekend for Pohnpei and Kosrae, becoming gentle to moderate. Fresh
winds will continue at Majuro through the weekend.

Western Micronesia...
Overall, not many changes were made to this forecast package. The
area of convection that was formerly JTWC Invest 92W is situated
just south of Palau. For the most part, the bulk of the showers have
remained just south of Palau`s southern coastal waters. Scattered
showers will be possible across Palau tonight as the area of
convection remains just south of Palau. Shower coverage is expected
to increase across Palau and Yap tomorrow as a trade-wind trough
moves into the region. A fairly active weather pattern looks to
develop near Chuuk this weekend with guidance developing a Near
Equatorial Trough (NET) across Chuuk State. Towards the middle and
end of next week, quieter conditions look to setup across Palau and
Yap while Chuuk remains fairly active.

The Small Craft Advisory was extended until 5 AM Saturday morning
for Yap and Palau. Palau buoy has generally ranged between 9 and 10
feet today and the latest ECMWF-Wave delayed the decrease in seas
until later tonight. Palau`s buoy is also likely missing some of the
secondary north swell due to it`s position on the eastern coast of
Palau. Combined seas are expected to fall below Small Craft Advisory
criteria later tonight with surf also falling below hazardous
criteria. Another northerly swell event looks to impact western
Micronesia late this weekend and into early next week. This may
bring another round of hazardous conditions for small craft and
hazardous surf to Palau and Yap. Travel between islands will likely
remain choppy for Palau and Yap for the next several days.

&&

.GUM WATCHES/WARNINGS/ADVISORIES...
GU...High Rip Current Risk through this afternoon for GUZ001.

     High Surf Advisory until 5 PM ChST this afternoon for GUZ001.

MP...High Rip Current Risk through this afternoon for MPZ001>003.

     High Surf Advisory until 5 PM ChST this afternoon for MPZ001>003.

Marianas Waters...None.

&&

$$

Marianas: Slagle
East/West Micronesia: Schank