116
FXPQ50 PGUM 061809
AFDGUM

Area Forecast Discussion
National Weather Service Tiyan GU
409 AM ChST Fri Mar 7 2025


.Marianas Update...
No meaningful edits were needed to the forecast tonight. Typical dry
season regime, isolated showers for the Marianas. Combined seas are
around 4 to 6 feet and is anticipated to gradually build to 6 to 8
feet by Monday. Winds are expected to remain gentle to moderate. Fire
danger rating has climbed to 381 which remains moderate.

&&


.Eastern Micronesia Update...
Not much is happening weather-wise, with typical dry-season trades
in the moderate to fresh range, and seas of 6 to 8 feet near Pohnpei
and Kosrae, and about a foot higher for Majuro. The latest MIMIC also
show lower PWAT (Precipitable Water Values) of ~1 to 1.5 inches.

Look for isolated showers to continue area-wide for the next 5 to 7
days, before things become more convectively active, as there may be
a developing ITCZ Inter-Tropical Convergence Zone) forming a week to
10 days out.

&&

.Western Micronesia Update...
Similar to locations further east, isolated showers will continue
for Yap and Chuuk the next 5 to 7 days, as you`ll be farther-removed
from the "deeper" moisture and better surface convergence to your
south.

For Palau, however, you`re right on the edge of this and may see
low-end scattered shower coverage, with perhaps a thunderstorm,
through the Saturday night. This (the edge of deeper moisture/better
convergence) moves further away with just isolated shower coverage
expected for the first half of next week.

Seas will remain in the 6 to 8 foot range through the period, with a
light northerly swell developing Saturday night. Gentle to moderate
trades will prevail for Palau, with moderate to fresh winds at Yap
and Chuuk.

&&

.Prev discussion... /issued 533 PM ChST Thu Mar 6 2025/

Marianas Synopsis...
Satellite imagery shows isolated showers and partly cloudy skies
across the Marianas. Scattered showers are seen over the northern
CNMI, associated with a trade-wind trough nearby. East of the
Marianas, patchy showers can be seen, associated with areas of
shallow troughing and low-level trade wind convergence. Surface
observations and scatterometry show mostly moderate trades with
occasional fresh gusts. Latest buoy data indicates 4 to 6 foot seas
near the islands.

Discussion...
A mild trade wind pattern is in place across the Marianas. Satellite
and model trends point to a gradual increase in showers late overnight
for the northern CNMI, Saipan, and Tinian, as a subtle trough enters
the area. Similar weak, short-lived features embedded in the trade
winds will define the weather pattern for at least the next week,
occasionally interrupting what will otherwise be dry and quiet
conditions. Friday onward, showers are expected to remain isolated
throughout the forecast period, with occasional increases in
cloudiness and local coverage. Winds will remain gentle to moderate
for the remainder of the week as a col passes north of the area,
increasing slightly this weekend as the subtropical ridge begins to
reassert itself north of the region.

Marine/Surf...
Gentle to moderate trade winds will prevail for the period. Combined
seas of 4 to 6 feet will continue through Friday night. A weak pulse
of north swell arrives by Friday morning, before a stronger north
swell moves in Sunday night, in addition to slightly higher trade
swell. Seas will gradually increase over the next few days, coming up
to 6 to 8 feet by Monday. A pulse of elevated north to northeast
swell looks to graze the region around Tuesday, which may bring seas
up another foot or so by mid next week. These conditions will
maintain a moderate risk of rip currents for north and east facing
reefs for at least the next few days. Additionally, a moderate risk
of rip currents will continue for south facing reefs tonight,
decreasing to low risk Friday as east and east-southeast swell
diminish.

Eastern Micronesia...
A dry trade-wind pattern extends across the region with the CIMSS
MIMIC Total Precipitable Water (TPW) satellite product showing
precipitable water values around 1.3 to 1.6 inches, which is on the
drier side for the tropics. This, along with the lack of major
weather features, is helping to keep showers isolated and skies
partly cloudy. Models keep most of the tropical moisture near and
south of the equator, so any showers that develop within the trade-
wind flow are expected to remain spotty and short-lived through the
weekend and into the middle of next week. An area of high pressure
passing north of the region will cause to winds to increase,
especially around Kosrae and the Marshall Islands, tonight through
Saturday as the pressure gradient across the region builds. This will
create breezy conditions across the Marshall Islands and Kosrae with
winds reaching up to 25 mph, especially during the daytime. Winds
will start to decrease Sunday and especially Tuesday as the high
pressure system moves well northeast of the region and is replaced by
a low pressure system well north of the region, decreasing the
pressure gradient.

Altimetry and buoy data shows seas are between 5 and 8 feet from
Pohnpei to the Marshall Islands this evening. As winds build to
around 20 knots through Saturday, especially across the Marshall
Islands and near Kosrae, seas are expected to build up to 9 feet by
Saturday. Right now, model guidance keeps winds below 22 knots and 10
foot seas east of the Marshall Islands, but any slight increase in
winds or seas would generate hazardous sea conditions, and
necessitate a Small Craft Advisory. Regardless, seas will likely be
choppy, especially around the Marshall Islands, so practice caution
if traveling between islands. The increase in winds near and east of
the Marshall Islands the next few days will keep the primary trade
swell elevated, and surf along east facing reefs of Kosrae around 9
feet through at least Saturday night. As such, the High Surf
Advisory for east facing reefs of Kosrae has been extended through
Saturday night. This may have to be extended even further as models
show only a slight decrease in the trade swell late this weekend and
into early next week. Pohnpei and the Marshall Islands have a higher
threshold of 12 feet along east facing reefs, and surf is not
expected to build that high over the next several days. A long-period
but small, north swell is expected to move into the region around
Sunday. This north swell is not expected to have much impact on sea
heights, but surf will build along north facing reefs late this
weekend. However, surf is expected to remain below hazardous levels
of 9 feet along north facing reefs.

Western Micronesia...
Trade-wind convergence is generating an area of unsettled weather
south of the forecast locations, with an embedded trough helping
spread showers north over parts of eastern Yap State. Relatively
quiet conditions persist north of this feature, across Yap and
Chuuk, with spotty showers around Palau from a minor trade-wind
trough passing through. This area of convergence is expected to shift
west-northwest and weaken over the next couple of days, such that
periods of scattered showers can be expected to move through Palau
through Saturday night, then a drier trade-wind pattern is expected
next week. Fair weather conditions are expected to continue for Yap
and Chuuk, before another trade-wind convergence pattern builds back
in, increasing shower potentials at Chuuk late next week.

Combined seas are 5 to 7 feet and up to 6 to 8 feet near Chuuk. Seas
are expected to increase an additional foot or two over the weekend
across Yap and Palau waters as a pulse in north swell moves through.
Gentle to moderate winds across Yap and Palau become moderate to
fresh over the weekend, whereas moderate to fresh winds persist
across Chuuk over the next several days.

&&

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

$$

Marianas Update: Bowsher
East/West Micronesia Update: Doll
Marianas: DeCou
East Micronesia: Schank
West Micronesia: Cruz