Rip Currents in Guam, December 7 to 11, 2024

Area Forecast Discussion
National Weather Service Tiyan GU
452 AM ChST Sat Dec 7 2024

.Update...
Doppler Radar shows low-end scattered showers arriving from the east
early this morning. Just minor touch-up changes were made to the
forecast package. Forecasts still indicate marine conditions will
become a bit choppy by Sunday with a little bigger trade-wind waves
arriving, and the risk of rip currents could then become high along
the eastern shores. Then, mostly fair weather is expected through
the longer term

&&

Eastern Micronesia update...
Only minor adjustments were made to the forecast. The ITCZ has
developed and is expected to continue to bring numerous to widespread
showers and isolated to scattered thunderstorms across eastern
Micronesia the next few days. The focus of the robust convection is
on Kosrae right now, but both the GFS and ECMWF show a gradual lift
northward towards Pohnpei tonight into Sunday.

&&

Western Micronesia update...
Only minor adjustments were made to the forecast. Shower and
thunderstorm activity continues to impact Palau and is expected to
increase in coverage across Yap State today. Relatively quieter
conditions are seen at Chuuk but coverage in showers and
thunderstorms are expected to increase tonight through Sunday night.

&&

.Prev discussion... /issued 632 PM ChST Fri Dec 6 2024/

Marianas Synopsis...
Mostly cloudy skies have built into Guam today while most of the CNMI
remains under partly cloudy skies. Satellite imagery shows scattered
showers over western Guam waters and isolated showers over much of
the region.

Discussion...
A weak surface trough is bringing in some scattered showers to the
Marianas. These showers are anticipated to be intermittent over the
next 24 hours. These showers will build from the south to the north
as a passing surface trough lifts. Once this trough passes, fair
weather is in store for the Marianas through the rest of this
weekend and most of next week.

Marine...
Altimetry shows combined seas of 4 to 6 feet to the west of the
Marianas. Ritidian buoy shows about 5 foot seas, while Tanapag Buoy
shows close to 6 feet. Seas are anticipated to build to between 6 and
8 feet over the weekend before gently dropping back down for next
week. Winds will build and become fresh over the weekend, then drop
back down to gentle to moderate range once this trough passes.

Eastern Micronesia...
A strong trade-wind surge and developing ITCZ (Inter-Tropical
Convergence Zone) remain the dominant features across the region.
Latest guidance and satellite trends show an increase in convection
throughout eastern Micronesia, with Kosrae and Pohnpei seeing the
heaviest rainfall. Have increased shower coverage for both Pohnpei
and Kosrae to widespread over the weekend as the ITCZ and surge peak
along with weak trade-wind troughs moving through the region.
Coverage will begin to decrease as the troughs exit the region and
the surge and ITCZ weaken. Overall, eastern Micronesia will remain in
a fairly wet pattern through the end of next week.

For the marine environment, the trade-wind surge brought increasing
swell and wind waves to the region, resulting in Small Craft
Advisories remaining in effect for all locations. Majuro will see
both strongest winds and highest seas, with fresh to strong winds and
near-gale gusts and seas reaching up to 11 feet over the weekend.
For Kosrae, seas and winds will be greatest over the northern waters.
Seas are expected to be around 10 feet with near-gale gusts at both
Pohnpei and Kosrae. Seas and winds will peak over the weekend and are
expected to slowly subside over the coming week at Kosrae and
Pohnpei. For Majuro, the Small Craft Advisory may need to be extended
as model guidance shows another surge in the trade-wind swell moving
through the Marshalls later early next week.

Western Micronesia...
A potential tropical disturbance is expected to develop southeast of
Mindanao over the next few days, allowing a convergence zone to
build upstream that will bring much more significant weather to Palau
and Yap the next coming days. Numerous intense showers with strong
gusts are expected tonight, continuing through Saturday as the
convergence zone shifts westward; this will allow showers to begin to
taper down in coverage over Palau by early next week. Yap will see
on-and-off showers taper down by early next week as well, allowing a
brief dry regime to ensue, followed by another trade-wind surge
forming nearby by Monday.

Pleasant weather over Chuuk is expected to begin to deteriorate
starting Saturday, followed by an intense trade-wind surge moving in
by Sunday. This surge will bring numerous heavy showers with some
thunderstorms and strong gusts through Sunday night. After,
conditions will begin to improve as the aforementioned surge shifts
westward toward Yap, followed by another surge developing within the
ITCZ.

Combined seas of 4 to 6 feet will persist over Palau and Yap through
the weekend, potentially increasing a foot or two by midweek. 5 to 7
foot seas near Chuuk are expected to reach 10 feet as early as
Saturday night, potentially producing conditions hazardous to small
craft; as such, a Small Craft Advisory may be issued Saturday
afternoon, if conditions warrant.

&&

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

Marianas: Simpson
Micronesia: Williams