NWS Guam wrote its last area forecast discussion before the first event at Aug 31, 8:08 PM UTC, 3 hours 52 minutes earlier.
Area forecast discussion, Aug 31, 8:08 PM UTC, 3 hours 52 minutes before
Area Forecast Discussion
National Weather Service Tiyan GU
608 AM ChST Sun Sep 1 2024
.Marianas Update...
Just refreshed the winds, which took them down a couple miles per
hour. This was in good agreement with the 12Z gradient wind which was
only 8 knots. Otherwise little change, we are still in an unsettled
pattern, with scattered showers expected through at least Wednesday
night.
Combined seas look to remain around 3 to 5 feet and winds at 5 to 10
knots through Thursday. Directions will be mainly east or southeast.
There will be an east and a west swell competing after the first day
or two, so we will need to add a secondary swell.
&&
.Eastern Micronesia Update...
Minor changes were made to the short-term forecast. Scattered showers
were re-introduced into the Pohnpei and Kosrae forecasts based on
satellite observations and model data. Satellite shows a cluster of
showers and isolated thunderstorms just east of Kosrae racing
westward. Both the GFS and ECMWF show these showers and thunderstorms
moving across Kosrae today. The ECMWF is also showing scattered
showers developing across Pohnpei today where low level flow remains
convergent.
No change was made to the marine forecast. Gentle to moderate winds
are expected to continue, with occasional fresh winds possible at
Majuro and Pohnpei this week. Combined seas of 3 to 5 feet at
Pohnpei will build slightly, reaching 4 to 6 feet at Pohnpei. For
Majuro, seas of 4 to 6 feet are expected to reach 5 to 7 feet over
the weekend.
&&
.Western Micronesia Update...
Chuuk's forecast was adjusted to account for the widespread
convection that is currently seen on satellite. Shower coverage
should decrease to numerous this afternoon. Elsewhere the forecast
remains status quo. Satellite currently show a lack of convection
over Palau, but the ECMWF shows the lull ending this afternoon with
another round of convection. This appears to be backed by satellite
showing a new round of developing convection to the east of Palau.
Slight changes were made to the marine forecast with combined seas
remaining in the 4 to 5 feet range for Yap and Palau instead of the 4
to 6 feet range previously forecasted. These seas will generally fall
to 3 to 4 feet early this week. Combined seas will remain between 3
and 5 feet for Chuuk through the forecast.
&&
.Prev discussion... /issued 651 PM ChST Sat Aug 31 2024/
Marianas Synopsis...
Gentle to moderate southeasterlies prevail in the region. Satellite
imagery indicates some showers in the outer coastal waters of Guam,
Tinian and Saipan. Ritidian buoy indicates seas are about 4 feet.
Discussion...
Little change has been made to the Marianas forecast. Expect low-end
scattered showers for much of the forecast period, as an unsettled
pattern lingers. This is mainly due to Invest 92W well southwest of
the region dragging a monsoon trough northward during the next week,
allowing minor perturbations in the trades to move across the
Marianas.
Marine...
Gentle to moderate east-southeasterlies and combined seas of 3 to 5
feet continue across the Marianas through tonight, staying as such
for much of next week. A moderate risk of rip currents is expected
along east facing reefs, while the risk of rip currents remains low
along south, west and north facing reefs, for at least the next few
days. Increasing west to southwest swell will likely result in rip
current risk becoming moderate along south and west facing reefs by
the middle of next week.
Tropical systems...
JTWC's Invest 92W is centered near 11N131E well northwest of Palau,
continuing its northwest trek over the open waters of the Philippine
Sea. This system is becoming better organized, producing bands of
moderate to deep convection across southeast, southwest, and
northwest quadrants outwards from the center. Although this feature
is moving away from Palau, numerous showers continue to develop along
the far southern peripheries of said feature, including over Palau.
92W is expected to continue moving northwest, exiting Guam's AOR
sometime tonight, hugging the eastern coasts of the Philippines early
next week.
Eastern Micronesia...
A weak ITCZ (Inter-Tropical Convergence Zone) stretches across
Pohnpei and ends just west of Kosrae. Two trade-wind troughs are
seen traversing the ITCZ. These features are interacting to produce
numerous showers and isolated thunderstorms across Pohnpei this
evening. By midnight, the troughs are expected to be far enough west
to allow a dry pattern to move into Pohnpei. Both troughs are west
of Kosrae, allowing a drier pattern to move over the island. For
Majuro, dry conditions look to continue for the atoll through
Sunday. For early next week, weak trade-wind convergence and a series
of weak troughs look to move through eastern Micronesia, bringing
increased convection to all three locations Sunday night thru Monday
for Majuro and Kosrae, and through Monday night for Pohnpei. A drier
pattern will then move into the region and continue through midweek
next week. For the last half of next week, models are favoring the
development of a stronger ITCZ from Majuro, across Kosrae and
Pohnpei, possibly into the far eastern portion of western Micronesia.
As this ITCZ develops, modest trade-wind troughs are expected to
interact with the convergence to produce periods of increased
convection to all three locations. It is difficult to narrow down
when there will drier periods this far out, therefore, maintained
POPs (Probability of Precipitation) around 50 percent Wednesday night
into next weekend.
Marine conditions look to remain fairly calm over the next several
days, with mostly gentle to moderate winds through the middle of
next week. However, Majuro and Pohnpei could see occasional fresh
winds around midweek next week. Seas of 4 to 6 feet are expected
through the next several days. Seas could reach up to 7 feet around
Thursday next week at Majuro.
Western Micronesia...
Recent Himawari visible satellite data shows numerous showers and
isolated thunderstorms building to the south of Palau, embedded
within the monsoon southwesterlies wrapping into Invest 92W. Latest
scatterometry winds show 10 to 20 kt west-southwesterlies about 170
nm southwest of the circulation center. Recent observations at Palau
show moderate gusts from the south-southwest. Invest 92W has moved
more rapidly than anticipated and is currently centered northwest of
Palau near 11N131E. Models indicate it will continue to move
northwest over the next few days, intensifying over the open waters
of the Philippine Sea. Although 92W is moving away from Palau,
numerous showers continue to develop along the far southern
peripheries of the system and are expected to bring heavy rainfall
and strong gusts tonight through Sunday afternoon. Showery conditions
will diminish overnight Sunday into Monday, with drier conditions to
follow through the mid-week period. Yap can expect a similar wet
pattern but with fewer showers and lower gusts expected through the
weekend, followed by fairly dry conditions during the mid-week.
Scattered showers are seen developing over Chuuk State in the latest
satellite imagery, and are expected to become numerous overnight
with isolated thunderstorms as a surface trough pushes west over the
area. Conditions should dry out Sunday night as the trough moves on,
but additional disturbances will increase showers at times through
Tuesday night, with drier weather to arrive Wednesday.
No significant changes to the marine forecast for now. Seas are
expected to remain between 3 and 4 feet at Chuuk and could reach as
high as 4 to 6 feet for Yap and Palau. Gentle to moderate winds are
expected at Yap and Palau for the remainder of the weekend, with
occasional fresh winds at Palau. The main concern will be the locally
heavy showers reducing visibility with gusty winds near heavier
showers and thunderstorms. Chuuk can expect light to moderate winds
through the middle of next week.
&&
.GUM WATCHES/WARNINGS/ADVISORIES...
GU...None.
MP...None.
Marianas Waters...None.
&&
Marianas: Montvila/Stanko
East Micronesia: Kleeschulte/Williams
Micronesia: DeCou/Williams