Area Forecast Discussion
Issued by NWS
FXPQ60 PGUM 241958
Area Forecast Discussion
National Weather Service Tiyan GU
552 AM ChST Tue Oct 25 2016
.Synopsis...East to Northeast trade-winds and isolated showers
prevail across the Marianas this morning.
Did update winds with new GFS40 data otherwise little change to
current forecast. VAD wind profile indicted winds from the east
at around 15 mph. Scatterometer data from last night should a
circulation near 6N142E. High pressure was located to the north
around 20N. The pressure gradient between these two features will
elevate slightly the winds over the Marianas today the part of
Wednesday with east winds of 10 to 20 mph expected.
A dry season weather pattern will settle in through the week with
only partly cloudy skies and isolated showers expected. Trade-
wind convergence will bring an increase in clouds and an higher
chance of showers Friday night through Monday.
Buoy data show seas between 3 to 5 feet this morning. There is an
east swell and Ritidian buoy did show a north swell. Models show
both swells persisting through the forecast. Expect surf on east
facing reefs to be 4 to 6 feet today. Surf on north facing reefs
will be 3 to 5 feet but is expected to increase slightly Wednesday
Showers and thunderstorms associated with a surface trough west
of Chuuk are slowly moving away to the west, however, an extended
surface trough stretches from near Pohnpei eastward across
Kwajalein and to the Date Line. Scatterometry indicates a possible
weak circulation near Kwajalein near 8N167E. Sowers and
thunderstorms near Majuro will taper off this morning, but with
the trough nearby, isolated thunderstorms will persist for the
next several days. Over the next several days, models keep the
focus of convection closer to 10N near the convergence boundary of
southeast winds across Micronesia and east-northeast trades north
of 10N. Both GFS and ECMWF show the circulation near Kwajalein
eventually dissipating within the trough.
A small long-period north swell will gradually diminish over the
next several days.
Reasoning for the Chuuk forecast can be found under the Eastern
Micronesia section above.
A weak circulation is seen southeast of Yap near 6N142E. Most
showers and thunderstorms are found to the northeast of the center.
The circulation will slowly move west, bringing unsettled weather to
both Koror and Yap the next several days. Shower coverage is limited
at the moment, but if showers begin to develop over a larger area,
Yap and Koror forecasts may need to be updated for increased showers
in the coming days. In the longer range, models hint at a monsoon
trough pattern developing along 5N, possibly with a secondary weak
circulation forming west of Chuuk late in the week.