067
FXPQ50 PGUM 280627 CCA
AFDGUM

Area Forecast Discussion...CORRECTED
National Weather Service Tiyan GU
427 PM ChST Fri Feb 28 2025

Corrected Advisory section and typos.

.Marianas Synopsis...
Latest ASCAT analysis and satellite imagery shows fresh to strong
northeast trades, mostly cloudy skies, and isolated to scattered
showers, associated with a shear line passing near Guam and Rota.
Buoy and altimetry data show seas between 7 and 10 feet.

&&

.Discussion...
A shear line continues to supply a series of light to moderate
showers across Guam and Rota today. Mostly cloudy to cloudy skies and
scattered showers are expected to persist through Saturday night
before the shear line further weakens and pushes south of the region
Sunday. Moderate to strong northeast trades continues through the
weekend, turning east-northeast early next week, as the area of high
pressure to the north pushes eastward. Yesterday, rainfall measuring
sites across Guam and Rota reported an average of 0.5 to 1.5 inches
of rain, with one site reporting as much as 1.8 inches. Additional
wetting rains remain possible through Saturday, which would continue
to suppress fire danger for Guam. Comparatively, Tinian and Saipan
received only 0.05-0.15 inches of rain, demonstrating the change in
impacts depending on where a shear line intersects the region. The
transition out of shear line weather next week would allow vegetation
to gradually dry out again. Periodic upticks in cloud cover and
showers may still occur with the passage with weak trade-wind
troughs, but daily rainfall amounts look to stay below 0.20 inches.

&&

.Marine/Surf...
Based on latest surf observations and latest buoy data, a High Surf
Advisory is no longer supported for north-facing reefs. A high risk
of rip currents remain in effect along east-facing reefs due to
elevated trade swell. Buoys show northerly swell energy has
diminished, leaving a dominant signal of northeasterly swell.
Combined seas of 7 to 10 feet and 15 to 25 kt winds will continue to
generate rough and choppy seas, so the Small Craft Advisory remains
in effect through Sunday night.

&&

.Eastern Micronesia...
Satellite shows two areas of trade-wind convergence, one just south
of Pohnpei and pulling away from Kosrae and the other extending
across the southern Marshall Islands and south of Majuro. The zone
of convergence near Pohnpei is generating scattered showers and
isolated thunderstorms across the southern waters of Pohnpei lifting
up and over the island, and this should continue through tonight
before pulling away to the west Saturday. For Majuro, the trade
convergence to the south will move west-northwest, causing isolated
showers tonight to become scattered Saturday. Drier weather is then
expected to move back into Majuro Saturday night as the convergence
continues westward, with a dry pattern expected across the Marshall
Islands through at least the middle of the upcoming week. Kosrae is
expected to be fairly dry tonight and Saturday, before the area of
convergence currently south of Majuro drifts westward into Kosrae
Sunday and into Pohnpei Monday, with showers expected to linger into
the middle of the upcoming week before the convergence starts to
fragment and weaken. Models show winds increasing across the region
around Wednesday as an area of high pressure move north of the
region.

Moderate to fresh trade winds and seas generally 6 to 8 feet, are
expected through the weekend and into early next week. Models show
winds increasing slightly around Wednesday to around 20 kt and seas
starting to build to 9 feet. This is just below hazardous levels to
small craft, so it will be something to watch for next week. An
elevated northerly swell remains, however, the easterly trade swell
is still dominant across the region. A longer period northerly swell
is expected to move through the region this weekend, increasing surf
along north facing reefs. For now, the forecast is calling for surf
to remain below hazardous levels of 9 feet as floating buoys north
of the region are not showing much of a sea increase as this swell
passes, but an increase in the primary period from 10 seconds to 13
seconds. However, high tides will be above normal through Monday due
to a new moon phase. The wave run-up forecast produced by PacIOOS is
showing the potential for some minor coastal inundation or wave
splash-up along north and east facing shores at Majuro due to its
low elevation. Any inundation is expected to be minor but decided to
issue a Coastal Flood Statement to highlight this potential,
especially for any low lying roads or properties along north and east
facing shores that are exposed to the north and east swells
affecting the region.

&&

.Western Micronesia...
Satellite imagery this afternoon shows patchy showers and cloud cover
near Yap Proper and the Republic of Palau, but to the southeast,
significant cloud cover and disorganized, widespread convection are
seen covering much of Yap State. This activity is associated with a
broad trough, which stretches south-southeast from southeast of Yap
Proper near 9N139E to roughly 2N140E. Further east, showers are
scattered both north and south of Weno, Chuuk, associated with
additional weak troughs and trade-wind convergence along the backside
of the aforementioned trough. Showers look to remain scattered near
Chuuk tonight, and become low-end scattered (30 percent chance of
showers) for Yap and Palau as the trough lifts gradually northwest
towards these forecast points. The bulk of the showers and isolated
thunderstorms will arrive this weekend, however, looking to peak
Saturday night near Yap Proper and on Sunday for Palau, as the trough
crests overhead. This disturbance looks to exit the region by Monday
morning. However, convergence along the backside of the trough,
followed by additional, weaker troughs, will keep showers scattered
near Palau through much of next week. Most of these showers look to
stay south of Yap Proper, however.

For Chuuk, shower chances remain scattered through Saturday as
additional weak troughs cross the area, diminishing to isolated
coverage early next week as a drier trade regime becomes dominant.
Embedded troughs within ITCZ-like fragments will increase showers
from time to time next week over Chuuk State, mainly south of Chuuk
Lagoon.

Babeldaob buoy data and altimetry data show that sea conditions have
relaxed near Yap and Palau as winds and trade swells subside, with 7
to 9 ft combined seas seen across much of the region. As north swell
has slightly diminished, corresponding surf for north-facing reefs
has fallen below hazardous levels, and the High Surf Advisory has
expired.


&&

.GUM WATCHES/WARNINGS/ADVISORIES...
GU...High Rip Current Risk through late Sunday night for GUZ001.

MP...High Rip Current Risk through late Sunday night for MPZ001>004.

Marianas Waters...Small Craft Advisory until 5 AM ChST Monday for PMZ151>154.

&&

$$

Marianas: Cruz
East Micronesia: Schank
West Micronesia: DeCou