927
FXPQ50 PGUM 142003
AFDGUM

Area Forecast Discussion
National Weather Service Tiyan GU
603 AM ChST Sat Jun 15 2024

.Marianas Synopsis...
Satellite imagery is showing generally partly cloudy skies and
isolated showers. Increasing skies and showers, along with a few
thunderstorms, are approaching the Marianas from the east. Latest
altimetry data and Ritidian buoy are indicating seas of 4 to 6 feet.

&&

.Discussion...
The TUTT cell now northwest of the Marianas continues to push west
away from the region, but will still provide divergence across the
Marianas today. In addition, a subtle trade trough will push across
the Marianas. Latest satellite imagery is showing an uptick in
showers east of the Marianas, and a few lightning strikes have also
been detected. Based off the latest satellite and model guidance,
have lowered shower coverage to scattered through tonight, with
isolated thunderstorms. As the features move through the Marianas,
they will also increase the potential for gusty winds with the
heavier showers and thunderstorms, with gusts to 30 mph possible. By
Sunday, a drier pattern looks to return to the region. This dry
pattern looks to be short lived for Guam and Rota, however, as a weak
circulation is expected to push through just south of Guam, bringing
another round of increased convection to Guam and Rota Monday
through Tuesday. By Tuesday evening, the dry pattern is expected to
return to Guam and Rota and continue through Friday.

&&

.Marine/Surf...
Gentle to moderate trades will prevail through the weekend into next
week. Combined seas of 4 to 6 feet will build to between 5 and 7
feet by tonight as the trade swell strengthens. Scattered to numerous
showers and isolated thunderstorms are expected over the waters
through tonight, and could bring some gusts around 25 knots.

A moderate risk of rip currents is expected to continue along east
facing reefs, and the rip risk is expected to become moderate along
north facing reefs by Sunday. The rip risk is expected to remain low
along south and west facing reefs.

&&

.Eastern Micronesia and Chuuk...
Overnight scatterometry data indicated a loss in cross-equatorial
flow for the Inter-Tropical Convergence Zone (ITCZ). The ITCZ has
fragmented into a series of trade-wind troughs across Chuuk, Pohnpei,
and Kosrae States, however, an area of moderate to strong trade
convergence still extends across Majuro, ending at a trough to the
east of Kosrae. A tropical upper-level tropospheric trough (TUTT) to
the north is also helping deepen convection in this area and sweep
upper-level cloud debris east-northeastward alongside the TUTT,
maintaining cloud cover over Majuro. Further west, upper-level
diffluence is also aiding convection associated with a surface trough
moving through Chuuk. Model guidance continues to depict a
fragmented ITCZ pattern, meandering across the region through the
weekend and this upcoming week, convection focusing around a series
of trade-wind troughs moving through the boundary, keeping periods of
scattered showers and isolated thunderstorms through most of next
week.

Combined seas are expected to be 3 to 5 feet across most of the
region and up to 6 feet at Majuro over the next several days.
Scatterometry data shows gentle to moderate winds across the region
and mainly moderate winds around the Marshalls.

&&

.Western Micronesia for Palau and Yap...
A surface trough has moved over Yap early this morning, and
satellite showed showers quickly developing, so increased POPs as a
result. Over the course of the day, model guidance shows this feature
weakening over Yap, however the southern portion of the trough will
continue to move westward over Palau, increasing showers there this
afternoon. Scatterometry data overnight showed weak westerlies moving
across the far southern islands of Palau, that would be key for a
monsoon trough. So far, models show this is as a weak feature,
however the convergence between weak west-southwesterlies and
approaching trade-wind troughs will keep weather fairly active in far
western Micronesia. Expecting thunderstorm potential to lessen
Sunday and Monday as the TUTT continues to pull away from the region.


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