010
FXPQ50 PGUM 222044
AFDGUM

Area Forecast Discussion
National Weather Service Tiyan GU
644 AM ChST Mon Sep 23 2024


.Marianas Synopsis Update...
The forecast was left in good standing last night, so only minor
updates were needed. A passing trough has flared up convection in the
region. Showers as of this writing were light with a few areas that
make get a short-lived heavier shower. Lightning has been observed
with these showers. The cloud tops are warming which suggests that
the showers are in the final stages of their life cycle.

&&

.Tropical systems Update...
Invest 91W (sub-low) is a lack luster circulation near 12N152E,
according to ASCAT last night. Currently, this system looks to be
falling apart into an open trough. 91W is expected to bring some much
needed moisture to the Marianas near the middle of the week. This
system will continue to be monitored as it progresses across the
region.

&&

.Eastern Micronesia Update...
With at least 5 days of isolated showers, the forecast for Eastern
Micronesia was pretty homogeneous. Some clouds were slow to get out
of the way at Pohnpei though, which led to the only change in this
forecast... For today, Pohnpei is now partly sunny instead of partly
cloudy. Otherwise, everything is looking just fine.

Seas at Pohnpei and Kosrae will be 2 to 4 feet. Seas at Majuro will
be 3 to 5 feet. Winds will be 5 to 10 knots across the area. These
will all work together to extend the peaceful reign of benign marine
conditions across Eastern Micronesia.

&&

.Western Micronesia Update...
A somewhat wet pattern persists over Yap and Koror, nothing like we
had the past week or two though. Yap is in a brief lull right now.
The forecast had this handled, so no changes were needed.

Seas will be 2 to 4 feet throughout Western Micronesia, with winds
of 5 to 10 kt. This will extend the run of benign marine conditions
for Western Micronesia as well.

&&

.Prev discussion... /issued 444 PM ChST Sun Sep 22 2024/

Marianas Synopsis...
Satellite and radar observations show isolated showers across the
Marianas with scattered showers seen just to the east and southeast
of Guam`s coastal waters. Ritidian and Tanapag buoys show combined
seas between 2 and 4 feet.

Discussion...
A few changes were made with this forecast package. Scattered showers
are expected to develop overnight and into Monday. Precipitation
chances look to increase this week as a plume of moisture that is
associated with Invest 91W move over the Marianas. A monsoonal-like
pattern will set up across the Marianas with gentle to moderate
westerly winds towards the middle of the week. At this time, the
monsoonal pattern and Invest 91W appear to be little to low impact
for the Marianas with low development chances. Please see the
Tropical systems section for more details. Continue to monitor
forecasts for any potential changes in the development of 91W.

Marine...
Seas look to remain benign with combined seas of 3 to 5 feet expected
for much of the week at this time. Moderate to fresh winds of 15 to
20 knots may be possible as Invest 91W lifts away from the Marianas
later this week. Although marine conditions look to remain calm this
week, the forecast could change significantly depending on the
development of Invest 91W. Continue to monitor forecasts for future
updates.

Tropical systems...
Joint Typhoon Warning Center`s Invest 91W has moved rapidly northwest
over the last 12 hours. Latest model guidance indicates that 91W
will slow down considerably over the next couple days and approach
the Marianas around Tuesday night or Wednesday. Models don`t favor
much intensification of this circulation, with increased convection
and winds of 20 to 25 mph possible around midweek as it passes
through the Marianas. Invest 91W will continue to be monitored over
the next few days.

Eastern Micronesia...
Eastern Micronesia has entered into an unseasonable dry period. This
dry period looks to continue across the region into the weekend. As
weak surface troughs move through the region, the islands could see
brief periods of increased showers, though overall, look for POPs
(Probability of Precipitation) to remain around 20 percent.

No changes to the marine forecast. Combined seas of 2 to 3 feet will
continue for Pohnpei and Kosrae, with 3 to 4 feet continuing for
Majuro. Light to gentle trade winds will continue through the week.

Western Micronesia...
A broad west-southwest to east-northeast oriented trough stretches
across western Micronesia and to the south of the Marianas, extending
through JTWC`s Invest 91W near 12N152E. Satellite shows a region of
scattered to numerous showers focused along the trough`s axis, mainly
to the east-southeast of Yap and west of Chuuk. Based on model
guidance and latest satellite trends, showers look to remain sparse
for Palau and Yap this evening before becoming scattered at times
overnight, and POPs were adjusted accordingly. The monsoon-like
trough extending into 91W will linger over western Micronesia for the
next few days before shifting northward during the mid-week,
bringing gentle to moderate southwesterly flow over Palau and Yap.
The associated convergence and moisture will yield on-and-off
scattered showers throughout the week to both locations. Chuuk
remains under the influence of a dry low-level ridge, and currently
sits within the southwesterly flow to the south of the trough`s axis.
Chuuk will remain fairly dry for the next few days, with a slight
increase in showers for the latter half of the week due to a broad
passing trade- wind trough.

Marine conditions remain fairly benign. Babeldaob buoy data shows 1
to 3 ft seas near Palau, and altimetry data shows 2 to 4 ft seas just
east of Chuuk. Light to gentle winds are expected throughout the
week, with no marine hazards anticipated.

&&

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

$$

Marianas: Bowsher
Micronesia: Stanko