989
FXPQ50 PGUM 061945
AFDGUM

Area Forecast Discussion
National Weather Service Tiyan GU
545 AM ChST Tue May 7 2024

.Marianas Synopsis...
Satellite imagery is showing mostly clear to partly cloudy skies
with spotty showers across the Marianas. Latest altimetry data is
indicating seas of 4 to 6 feet in the coastal waters. Winds are
gentle.

&&

.Discussion...
Just spotty trade showers expected through tonight. A surface trough
approaching from the east, along with an uptick in moisture being
pulled north along the trough, will pass through the Marianas by
later Wednesday into Thursday. An uptick in clouds and showers, but
not expecting coverage to become isolated. As we head towards Friday
into the weekend, the Near-Equatorial Trough (NET) is expected to
slowly drift northward, with a couple of embedded circulations. Some
model guidance is indicating one of the circulations developing into
a significant Tropical Cyclone (TC) as it moves through the NET south
of Guam, towards Yap and Palau. This could bring increasing showers
and thunderstorms to the Marianas late this week into the weekend,
mainly across Guam and Rota. Confidence in this happening, however,
is fairly low as the other model guidance only shows weak
circulations moving along the NET.

&&

.Marine/Surf...
Gentle winds will slowly increase through the week and become
generally moderate for Friday into the weekend, as the pressure
gradient becomes a bit tighter due to a disturbance pushing south of
the Marianas. Combined seas of 5 to 7 feet through tonight as an
elevated north to northeast swell passes through the region. Seas
will begin to slowly subside beginning by later Wednesday, lowering
1 to 2 feet by the end of the week.

A moderate risk of rip currents will continue along north and east
facing reefs. Surf will begin to subside by Wednesday evening,
dropping 1 to 2 feet along north and east facing reefs by Thursday,
however, the rip risk will likely remain moderate. Surf and rip risk
looks to build by the weekend along east facing reefs, as the trade
swell builds.

&&

.Tropical Systems...
An active pattern is seen on satellite over western Micronesia,
from south of Yap and Palau over to southwest of Chuuk. A NET is
evident on the latest ASCAT analysis, extending eastward from near
5N130E to a weak circulation, Joint Typhoon Warning Center (JTWC)
Invest 91W, centered near 4N136E. The NET continues eastward through
a second circulation, JTWC Invest 90W, centered near 5N143E. The
latest GFS and GFS Ensemble show one of these circulations developing
into a significant Tropical Cyclone (TC) as it moves through to the
south of Guam, towards Yap and Palau. Confidence in this happening,
however, is fairly low as the other model guidance only shows weak
circulations moving along the NET. This area will be monitored
closely over the next few days for any possible development.

&&

.Eastern Micronesia...
There was not a lot of change since last discussion as the forecast
has aged pretty well. Currently, Pohnpei, Kosrae and Majuro are in a
lull between cells of convection brought in by converging trades and
passing troughs. This kind of up and down pattern is expected to
last for the week. All in all, a fairly wet pattern is expected for
eastern Micronesia.

Altimetry shows combined seas of 5 to 6 feet over RMI. Winds are
expected to be fresh for today and tonight, then diminish to gentle
to moderate through the rest of the week. Seas are expected to
remain below advisory levels for this week, however, Kosrae may flirt
with, but not expected to meet the criteria line of 8 foot surf along
east facing reefs.

&&

.Western Micronesia...
The Near-Equatorial Trough or NET is the main producer of showers for
the region. There are a few troughs that will be making there way
into the region by Chuuk over the next few days. Currently the NET is
holding around 5 north, and currently has 2 embedded disturbances
(more on them in the tropical section). GFS, our most zealous model,
suggest something will become of one of these disturbances, while
almost all other models suggest these disturbances will dissipate
into troughs. Assuming the GFS is handling these disturbances
correctly this may bring much needed rain to Yap and Palau.

Chuuk on the other hand can expect to get zones of convergence and
trade-wind troughs moving through, and giving them showers off and on
for the remainder of the week.

Altimetry shows combined seas of 3 to 4 feet between Chuuk and Yap.
Overall, winds are expected to be gentle to moderate, with a spike
into fresh every now and then. Seas are expected to be fairly benign
this week.

&&

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

&&

$$

Marianas/Tropical: Slagle
Micronesia: Bowsher