091
FXPQ50 PGUM 132021
AFDGUM

Area Forecast Discussion
National Weather Service Tiyan GU
621 AM ChST Fri Jun 14 2024

.Marianas Synopsis...
Satellite imagery is showing partly cloudy skies with isolated
showers over Tinian and Saipan, with mostly cloudy skies and
scattered showers for Guam and Rota. Lightning has been observed over
the southern coastal waters. Latest altimetry and Ritidian buoy are
showing combined seas of 3 to 5 feet.

&&

.Discussion...
Deeper layer moisture, as noted by the CIMMS MIMIC precipitable
water values and model time heights, along with passing weak trade
troughs, will result in rounds of scattered showers through Saturday
night. The best potential for scattered coverage will be during the
evening hours through around 9 AM, as has been the trend over the
past few days. In addition, an approaching Tropical Upper-
Tropospheric Trough (TUTT) cell to the northeast of the Marianas is
approaching. As the TUTT cell moves over and west of the Marianas,
upper-level divergence will help promote the development of
thunderstorms through Saturday night as well. By Sunday, convection
looks to diminish as the surface and upper-level features both look
to push far enough west away from the Marianas. Expect generally
isolated showers next week, although some model guidance is
suggesting moisture and disturbances creeping north out of Micronesia
and possible bringing an uptick in showers at times, especially for
Rota and Guam.

&&

.Marine/Surf...
Gentle to moderate trades will prevail into the weekend. Combined
seas build to 4 to 6 feet today will slowly increase to between 5 and
7 feet over the weekend as trade swell strengthens. Weak trade-wind
troughs along with a TUTT cell to the northeast of the waters are
expected to bring rounds of scattered showers and a few thunderstorms
to the waters through Saturday night. Occasional strong gusts are
possible with the thunderstorms.

A moderate risk of rip currents is expected to continue along east
facing reefs and expected to remain low along all other reefs through
Saturday. Surf could increase about a foot beginning Saturday night
as the trade swell strengthens. This could bring a moderate risk of
rip currents to north facing reefs.

&&

.Eastern Micronesia and Chuuk...
An Inter-Tropical Convergence Zone (ITCZ) stretches across most of
the region, extending from the Marshall Islands to eastern Chuuk
State, mostly between 5N and 11N. No major changes were made to the
forecast. Scattered to numerous showers are expected through at
least the weekend and maintained the convectively-driven gusts winds
that the GFS has for Kosrae tonight, reaching up to 30 mph near
heavier cores. By Monday, the ITCZ is expected to fragment into a
series of troughs, keeping periods of scattered showers and isolated
thunderstorms through most of next week.

Altimetry shows combined seas across the region are around 3 to 5
feet, and model guidance depicts seas up to 6 feet east of the
Marshall Islands. Scatterometry shows gentle to moderate winds along
and south ITCZ, with moderate to fresh winds north of the axis and
embedded within heavier convection. Models continue to indicate
winds will generally be gentle to moderate for the region, with GFS
showing occasionally strong gusts with heavier showers within Kosrae
waters tonight. Trade swell slightly subsides, decreasing seas by a
foot this weekend.

&&

.Western Micronesia for Palau and Yap...
Satellite imagery shows clusters of showers and thunderstorms
developing in far western Micronesia this morning. Within the light
and variable wind field, there is a weak trough that drapes across
Palau and extends into eastern Yap State, as well as another trough
and trade-convergence affecting Yap Proper. Model guidance suggests
that shower coverage will shuffle around throughout the day, with
convection re-organizing near and west of Yap for the first part of
the day, then quickly pushing off and dissipating to the west of the
islands late afternoon for Yap and tonight for Palau. Additionally,
as the TUTT cell northeast of the Marianas and an attendant trough
extending to the southwest, continue to drift westward, the risk for
thunderstorms is expected to persist across Palau and Yap through at
least Saturday night. Afterwards, models show the TUTT lifting
northward which would help to decrease the potential for
thunderstorms on Sunday. However, an overall wet pattern is expected
for Palau and Yap, supported by troughs and trade convergence that
break off from the ITCZ and push westward into Palau and Yap through
at least early next week, along with some strengthening of the trade
winds around both locations.

Buoy and altimetry data show seas around 2 to 3 feet and
scatterometry data indicates light to gentle winds. Marine conditions
are not expected to change that much over the next several days,
except for a slight increase in trade swell that would bump seas up
to 4 feet around Yap next week.

&&

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

&&

$$

Marianas: Slagle
Micronesia: Cruz