Area Forecast Discussion
Issued by NWS
FXPQ60 PGUM 260612
Area Forecast Discussion
National Weather Service Tiyan GU
412 PM ChST Sun Mar 26 2017
It`s been a dry day in the Marianas, with scattered low clouds, no
showers, and moderate trade winds. Seas at the buoys range from just
under 4 ft at Tanapag to just under 5 ft at Ritidian.
The only real change from the previous forecast is the slight chance
of showers for tonight, based on satellite and the morning sounding,
which shows moisture only up to 4000 ft. The rest of the forecast is
unchanged, with isolated showers for the next week, and partly cloudy
skies becoming mostly cloudy Wednesday through Friday night. Winds
will increase for Tuesday through Friday, then decrease again
Saturday and Sunday.
Winds and seas will increase Tue-Fri as high pressure passes by to
the north, but at this point no advisories are expected to be needed.
Winds/seas will decrease again by the end of the week.
Satellite shows partly cloudy skies and isolated showers at Chuuk,
Pohnpei and Kosrae today. Meanwhile, a trade-wind surge with areas
of showers is moving across the Marshall Islands. GFS indicates the
showery weather will continue moving westward, probably to Kosrae by
Monday afternoon, then to Pohnpei by Tuesday, and Chuuk late Tuesday
or Wednesday. The pattern of trade-wind convergence and showers
extends eastward across the Date Line, so relatively wet weather is
expected most of this week.
Swell and wind waves associated with a trade surge will continue to
build from the Marshall Islands westward to Chuuk State thru tonight
and then peak from Monday to Wednesday. This will maintain hazardous
surf on Kosrae thru midweek, and may produce Small Craft Advisory
conditions at Majuro on Monday. In conjunction with an astronomical
high tide cycle of 5 to 6 feet above the average low tide, coastal
inundation is also possible at Kosrae and Majuro. Finally, seas
across Kosrae, Pohnpei and Chuuk States could yet become hazardous
for small craft operation this week.
A surface trough is edging across far Western Micronesia. Satellite
shows scattered showers and isolated thunderstorms moving over the
Koror area and isolated showers and thunderstorms near Yap. Shower
coverage across most of the area should decrease by Monday evening,
as the trough moves slowly west, but weather will remain unstable.
GFS model indicates a shear line will approach Yap and Koror from
the north about Wednesday, and a pattern of trade-wind convergence
will likely arrive from the east as this week progresses.
Trade-wind swell and wind waves will build starting Monday night as
surging trades approach from the east. Then a shear line digging
southward across the Philippine Sea will also introduce a north swell
by midweek. All these will cause surf and seas across the Republic
of Palau and western Yap State to rise which could reach hazardous
levels near midweek.