Area Forecast Discussion
Issued by NWS
FXPQ60 PGUM 200747
Area Forecast Discussion
National Weather Service Tiyan GU
550 PM ChST Fri Jan 20 2017
Partly cloudy skies with only a few light showers prevail over the
Marianas this afternoon. Moderate to fresh winds are present across
the coastal waters. Latest buoy observations show seas ranging from 7
to 9 feet.
Fairly dry conditions are seen over the Marianas this afternoon.
This is expected to continue through Sunday morning. On Sunday,
the shear line that moved through earlier this week, will drift
northward. Though diffuse, it is expected to bring another short
round of scattered showers to the Marianas through the day on
Sunday. Otherwise, isolated showers will continue into next week.
Another shear line is then expected to approach the islands late
Tuesday or Wednesday, bringing the risk of scattered showers to the
region for most of next week.
Latest buoy data shows seas continuing to subside through the
day. Seas now range from 7 to 9 feet and are expected to drop to
between 6 and 8 feet Saturday. Winds are also much weaker than
previously expected. Therefore, the Small Craft Advisory has been
cancelled. North swell has subsided sufficiently that surf has
also fallen below hazardous levels.
Fresh to strong trade winds are expected to continue from Chuuk
State eastward to the Marshall Islands over the next several days.
Latest IR satellite imagery reveals a series of old shearlines embedded
within the trades. The newest and strongest shearline is northeast of
Wake Island with an older weaker one to northeast of Kwajalein.
Some minor instability is producing some shallow convection near Majuro
eastward to the Date Line. These systems will keep periodic...mostly light...
showers in the Marshall Islands into next week. Shower activity near Kosrae
and Pohnpei should remain light and isolated into early next week. Unstable
conditions will bring scattered showers and the possibility of thunderstorms
to Kosrae and Pohnpei from Monday to Tuesday.
The major event for the area is the continued strong trade winds and the
persistent rough seas. Subsiding north swell has allowed surf across Pohnpei
State to drop below advisory levels. However, persistent trade-wind
swell and wind waves should maintain hazardous surf on Kosrae for
the next several days. Fresh winds and choppy seas will also create
hazardous conditions for small craft from Chuuk State eastward to
the Marshall Islands thru at least this weekend.
The rather dry pattern affecting Chuuk State will become moist and
unstable by Monday. This may in part be induced by the westward
propagation of one of the old shearlines moving through the deeper
The shearline that passed through the Mariana Islands yesterday is
producing convection from around 11N 150E westward into Yap State.
This will produce periods of isolated showers and thunderstorms for
Yap State. The GFS model suggests an increase in shower and
thunderstorm activity by Wednesday for both Yap State and the
Republic of Palau.
A strong ridge of high pressure currently over central China may
channel strong northeast winds across the Philippine Sea as it exits
China and moves eastward. We expect winds of 25 knots to persist
across Palau and Yap beginning Sunday and across Chuuk on Monday.
These winds will produce conditions hazardous to small craft and will
likely produce high surf conditions by early to mid-week. Therefore
need to monitor for another high surf event by early next week.