658
FXPQ50 PGUM 081917
AFDGUM

Area Forecast Discussion
National Weather Service Tiyan GU
517 AM ChST Thu Jan 9 2025

.Marianas Update...
Satellite and radar show lines of isolated showers moving northwest
across the Marianas early this morning ahead of a shallow trade-wind
trough, mainly over Guam and Rota with diminishing coverage to the
north. A dry trade-wind pattern will continue across the region
through early next week, and little change was made to the forecast
package.

Buoy data shows combined seas of 5 to 7 feet across the Marianas.
Recent altimetry data shows higher seas across the broader region,
with 7 to 9 foot seas east of the islands, and 8 to 10 feet west of
the area. Seas will gradually rise by around 1 to 3 feet as a larger
northerly swell and trade swell enter the area, potentially becoming
hazardous to small craft come Sunday. Gentle to moderate trades will
continue, becoming fresh at times tonight through Sunday. East facing
reefs may face a high risk of rip currents come Friday.

&&

.Eastern Micronesia Update...
The main focus was on Majuro for today and tonight, centered on two
items of interest. First, there`s a high probability for waves to
peak near 12 feet from the northern RMI to Majuro, extending further
south tonight into Friday. The north and east facing reefs will be
most at risk, where coastal inundation is possible at Majuro.
Additionally, mariners may face 9 to 13 foot seas and sustained
winds of 15 to 25 knots.

The other minor issue was trying to determine if the southern half
of Majuro`s coastal waters would see scattered showers, versus
isolated coverage, similar to Majuro proper and the remainder of the
RMI near and north of Majuro. As suspected yesterday, the plume of
higher moisture and better shower coverage potential looks to bypass
most of the area as it`ll be located just to the south of Majuro.

The remainder of the forecast for Majuro was unchanged, with no
significant changes made at Pohnpei and Kosrae.

&&

.Western Micronesia Update...
No significant changes were made as the forecast remains on track.

&&

.Prev discussion... /issued 452 PM ChST Wed Jan 8 2025/

Marianas Synopsis...
Satellite imagery shows mostly cloudy skies over Guam, and partly
cloudy skies over CNMI. Winds are gentle to moderate. Combined seas
are 5 to 7 feet.

Discussion...
Fair weather is expected through the middle of next week. Only real
change to be expected is whether it is partly cloudy or mostly
cloudy. Time heights show a rather large and very dry mid level
layer.

Marine...
Here is where the main concerns are for the Marianas. A quick north
northeasterly pulse is anticipated for Thursday night. This is due
to a longer period secondary swell coming in. This pulse may bring
sea condition up slightly for a brief time that night. For Friday and
much of Saturday seas will fall slightly before picking back up
again on Saturday evening into Sunday morning. The arrival of a
north swell around Sunday could raise seas to levels hazardous for
small craft.

Eastern Micronesia...
Satellite shows a band of scattered showers from over the central
Marshall Islands eastward to beyond the Date Line. This is an area of
stronger and slightly convergent trade winds. Models indicate the
patchy areas of showers will gradually edge toward Kosrae tonight or
tomorrow, and probably toward Pohnpei later. Otherwise a relatively
dry, but fresh to strong, trade-wind flow prevails across Eastern
Micronesia.

Small Craft and High Surf Advisories remain in effect for Pohnpei,
Kosrae and Majuro, and including Coastal Flood Statement for Majuro.
Combined seas of both north and northeast waves will build over the
whole region during the next couple of days, then very gradually
diminish over this weekend.

Western Micronesia...
A Near-Equatorial Trough (NET) remains anchored across the southern
extent of the region. Satellite and scatterometry data shows equatorial
westerlies south of Chuuk State and eastern Yap State, where
moderate to deep convection is occurring along the NET, whereas the
feature has broken down moving westward across the Republic of Palau
and into the Philippine Sea. Chuuk Lagoon is north of the NET
convection and a drier airmass is moving through as well, with MIMIC
TPW and 00Z sounding showing PWATs 1.20 to 1.40 inches. A fairly dry
trade-wind pattern will continue through the middle of next week with
a period of scattered showers expected Thursday night. In far
western Micronesia, a surface trough is between Palau and Yap and
will slowly drift westward, eventually becoming absorbed into the NET
in the coming days. This and trailing trade-wind convergence will
keep scattered showers in the area, primarily across Palau through at
least the weekend.

Dominant trade swell, background north swell, and moderate to fresh
trade winds will maintain choppy seas across the region. Arrival of
north-northwest swell for Yap and Palau, as well as an increase in
trade winds and swell, is expected to make marine conditions
hazardous over the weekend and into early next week. Winds may
occasionally reach hazardous levels of 22 kt for Chuuk as early as
Friday, but will continue to monitor subsequent model runs to
reassess the need for a Small Craft Advisory.

&&

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

$$

Marianas: DeCou
East/West Micronesia: Doll