313 
FXPQ50 PGUM 222023
AFDGUM

Area Forecast Discussion
National Weather Service Tiyan GU
623 AM ChST Sat Sep 23 2023

.Marianas Synopsis...
Satellite and radar indicating partly cloudy skies with isolated
showers. Ipan buoy and latest altimetry data showing seas of 3 to 5
feet.

&&

.Discussion...
The monsoon trough has sagged south, along with the better coverage
of showers and thunderstorms. Just isolated showers expected through
Sunday with a drier northerly flow over the region. An increase in
showers and potential for thunderstorms expected next week as the low
to our east, formerly Invest 96W, passes west through the Marianas and
models indicating a potential monsoon push and trough setting up in 
its wake.

&&

.Marine/Surf...
Combined seas of 3 to 5 feet expected through the weekend. Seas 
could rise 1 to 2 feet next week as an elevated west to southwest 
swell arrives. Winds look to be light to gentle for most of the 
period, possibly becoming moderate at times Sunday night into Monday.

A moderate risk for rip currents will continue for east facing reefs,
with a moderate risk possibly developing for south and west facing
reefs early next week as the west to southwest swell increases.

&&

.Eastern Micronesia...
The trough across eastern Micronesia continues to generate scattered
showers at and to the south of Pohnpei, Kosrae and Majuro. This 
feature will linger through Sunday, before the main axis of the 
monsoon trough across the Marianas, starts to retreat westward, and 
the trade winds begin to push back across eastern Micronesia. 
Overall, expect a wet pattern with chaotic flow for the rest of the 
weekend and into next week as models show a slow transition from the 
trough retreating westward to a overall pattern dominated by the 
trade winds and passing trade showers.

Altimetry data shows combined seas of 3 to 5 feet around Pohnpei and
Kosrae, and up to 6 feet near the Marshall islands. Expected seas to
increase by a foot or two around the Marshall Islands next week as
and elevated trade swell pushes into the region from across the Date
Line.

.Western Micronesia...
Not much has changed with the monsoon trough that stretches across 
the region to the north of western Micronesia. Satellite imagery 
shows isolated showers around Palau, while scattered showers are 
developing just to the north and northeast of Yap and Chuuk as they 
are closer to monsoon trough overall. A ridge of high pressure south 
of Palau and Yap will help to keep Palau drier through Sunday, while 
the monsoon trough is not expected to move much over the next couple 
of days which should keep Yap and Chuuk in a slightly wetter pattern.
For Yap, showers look to be more hit or miss as the more widespread 
and heavier convection is expected to remain to the north, along the 
monsoon trough. Chuuk is closer to the trough/disturbance in eastern 
Micronesia, which will help to increase the potential for showers 
around Chuuk into next week. After Sunday, models show the monsoon 
trough slowly retreating westward, while the ridge of high pressure 
drifts slightly north. For Palau and Yap, this will increase the 
pressure gradient near the islands, causing winds to become breezy 
Sunday night and into the middle of next week. This will also shift 
the zone of convergence along the monsoon trough, where showers are 
expected to become scattered at Palau around the same time.

Seas of 4 to 5 feet are expected tonight through Sunday. The increase
in winds mentioned above will also raise seas to 5 to 7 feet at
Palau and Yap Sunday night through Tuesday night. This increase in 
winds will also produce a short-period westerly swell that will also 
extend into Chuuk.

.GUM WATCHES/WARNINGS/ADVISORIES...

GU...None.
MP...None.
Marianas Waters...None.

&&

$$

Marianas: Slagle
Micronesia: Schank