842
FXPQ50 PGUM 061743
AFDGUM

Area Forecast Discussion
National Weather Service Tiyan GU
343 AM ChST Sun Jul 7 2024

.Marianas...

.Short-Term Update...
Introduced isolated thunderstorms in today`s forecast, as an upper-
level trough to the east is moving in and interacting with minor
surface disturbances to produce some lightning in eastern Guam waters
overnight. Otherwise, the weather and marine forecasts for the
Marianas remain unchanged.

&&

.Eastern Micronesia...

.Short-Term Update...
Satellite shows heavy showers and thunderstorms from south of Majuro
to the Tarawa area, while showers were scattered to numerous in the
area between Majuro and Kosrae. An ITCZ type pattern is causing
convergent trade winds in these areas of showery weather. Quiet
weather is currently over Pohnpei, but showers will gradually move
toward Pohnpei from the east today through Monday. Quiet weather is
also over Majuro today, but more active weather is expected to
develop for the RMI this week.

Combined seas of 4 to 6 feet are near Majuro and 3 to 5 feet are near
Kosrae and Pohnpei. Seas are expected to rise another foot or so by
tonight before gradually decreasing later this week.

&&

.Western Micronesia...

.Short-Term Update...
A complex surface trough remains over Western Micronesia, mainly
focused along 5N to 7N, from southern Chuuk State westward across
central Palau. Thunderstorms are developing at times since modest
upper-level divergence is over the region. Models indicate this
relatively unstable pattern will persist through the longer term.
Models also indicate the trough axis will move a little northward
this week, and seasonal-type southwest to west surface winds will
develop for Palau this week, hinting at monsoon flow.

Besides the westerly surface winds developing for Palau, benign sea
conditions are expected for Palau and Yap with combined seas ranging
between 2 and 4 feet. For Chuuk, seas will start in the 3 to 4 foot
range but should rise by 1 to 2 feet early this week to the 4 to 6
foot range. Seas will taper down 1 to 2 feet towards the end of the
week for Chuuk.

&&

.Prev discussion... /issued 528 PM ChST Sat Jul 6 2024/

Marianas Synopsis...
Satellite imagery shows partly cloudy skies across the Marianas with
spotty trade showers passing through the coastal waters. Winds are
gentle to moderate, with altimetry and buoy data showing combined
seas around 4 to 5 feet.

Discussion...
Weather across the Marianas remains fairly quiet as a fairly dry
trade-wind pattern extends across the region, north of 10N.
Satellite shows some isolated showers to the east of the Marianas,
developing along some weak trade-wind convergence, which should bring
some isolated showers to the islands tonight but any showers will be
short-lived. As discussed in previous forecasts, we been watching
for the potential for thunderstorms around Sunday as an upper-level
trough near Wake Island drifts westward. However, the upper-level
trough looks fairly weak and there as been a lack of thunderstorm
active along this trough, likely due to the lack of any notable
surface features. Based on this current trend and model data, decided
to reduce the potential for thunderstorms to Sunday night as the
when models agree the trough will likely be the closest to the
Marianas before it dissipates. Looking towards next week, most of the
active weather features are expected to remain south of the
Marianas, across the rest of the Micronesia near and south of 10N,
with some trough occasionally clipping the Marianas around the middle
of next week, potentially bringing some showers to the Marianas
though the risk for thunderstorms or heavy rainfall looks unlikely.

Marine...
Gentle to moderate trade winds and combined seas of 4 to 5 feet will
continue through at least Thursday. There is still the potential for
isolated thunderstorms but it has been reduced to Sunday night as
that is when the upper-level trough near Wake Island will likely
reach its closest point to the Marianas before models have the trough
dissipating. Otherwise, weather and sea conditions look to be fairly
benign for the rest of the weekend and through most of next week.

Eastern Micronesia...
Satellite observations show scattered showers and isolated
thunderstorms to the west of Kosrae and moving west towards Pohnpei.
This round of showers and storms will impact Pohnpei through
tomorrow. The models show another round of storms developing near and
just east of Kosrae late tonight. There is some difference with the
GFS holding off the bulk of the precipitation until Sunday, but kept
scattered showers in the forecast to bridge the more bullish ECMWF
with the more bearish GFS. The pattern looks to become more active
early next week as a Near Equatorial Trough (NET) or even some
semblance of the ITCZ looks to build into eastern Micronesia.

Altimetry data shows seas in the 4 to 6 feet range near Majuro and 3
to 5 feet near Kosrae and Pohnpei. Seas are expected to rise another
foot or so late this weekend into this week before gradually
decreasing late this week.

Western Micronesia...
Little change was made to the previous forecast. Conditions appear
mostly quiet for Yap and Palau through early this week with isolated
to scattered showers possible. Guidance continues to hint towards the
trough that is impacting eastern Micronesia to reach Chuuk around
Tuesday. This would bring likely showers and a slight chance for
thunderstorms to Chuuk by Wednesday. This feature will continue to
move westward and may approach Yap and Palau by the end of the week.

Latest altimetry data shows seas of 1 to 3 feet near Palau. Benign
seas will continue for much of the period around Palau and Yap with
seas ranging between 2 and 4 feet. For Chuuk, seas will start in the
3 to 4 foot range but should rise 1 to 2 feet early this week to the
4 to 6 foot range. Seas will taper down 1 to 2 feet towards the end
of the week for Chuuk.

&&

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

$$

Marianas: Montvila
Micronesia: Simpson