Area Forecast Discussion
Issued by NWS
FXPQ60 PGUM 262127
Area Forecast Discussion
National Weather Service Tiyan GU
727 AM ChST Mon Mar 27 2017
A rather dry trade-wind regime remains anchored in place over the
Marianas waters. Deep tropical moisture is trapped well to the
south while an unseasonably late shear line is not all that far to
Deep convection remains sparse around the Marianas. It is expected
to pick up a bit as the shear line to our northwest approaches.
Nonetheless, this is quite late in the year for a shear line so
will have to watch this carefully. On this morning`s ASCAT there
is no clear source for the winds that are supposed to arrive just
48 hours from now. It is always possible they will develop in
situ, this seems a bit of a stretch at this time. However, for
now, it was hard to go against all the available model guidance,
so just undercut some of the most aggressive ones.
Seas rise from 4 to 6 feet today to between 8 and 10 feet on
Wednesday. How much of this, though, is wind wave due to the
expected winds mentioned above? If those winds do not materialize,
or do emerge but are underwhelming, the seas could be less. Even
if a small craft advisory is needed, it would likely be marginal
and rather short lived. At this time a high surf advisory is not
An overall unsettled pattern is now in place across Eastern
Micronesia. A band of trade-wind convergence lying near Majuro
will bring scattered showers and isolated thunderstorms to the
atoll later this morning. This band of convergence extends
westward to just east of Kosrae...then bends west-southwestward to
end southwest of Chuuk. latest model guidance shows this band of
convergence drifting northward over the next 24 hours, bringing
scattered showers and isolated thunderstorms to Majuro later this
morning. Showers will then spread to Kosrae by this afternoon.
Pohnpei will see the increase in showers around midnight tonight
and finally Chuuk late Tuesday morning. Unsettled conditions
will then continue through most of the week.
Swell and wind waves associated a trade-wind surge will continue
to produce hazardous surf and minor coastal inundation at Kosrae
through at least the middle of the week. As this surge moves
through the Marshalls, wind and seas will become hazardous to
small craft through tonight. Although High Surf conditions are not
expected at majuro, minor coastal inundation on east facing reefs
remains possible during high tide. Wind and seas are expected to
begin to subside this evening at Majuro, falling below Small Craft
Advisory levels by Tuesday morning.
The Chuuk forecast discussion is included with Eastern Micronesia
A benign pattern is now in place over yap and Koror, with only a
few showers in place over both locations. A trade-wind convergence
pattern that is currently affecting Eastern Micronesia will move
in over Yap and Koror later in the week. Unstable conditions are
expected to return to both locations around midweek as the trade-
wind convergence pattern reaches the area. The majority of the
showers are likely to remain to the south of Yap, but over Koror,
though increased convection is expected near yap as well. A
slightly further northward drift of the convergence zone could
increase showers to scattered at Yap. This will be monitored
closely over the next couple of days.
Increasing swell and wind waves associated with a trade-wind surge
is still expected over Western Micronesia, beginning this evening.
Small Craft Advisory levels are not expected at this time,
however, seas will be a little rougher than normal and mariners
should use more caution for inter-island travel. If the seas do
reach hazardous levels, it will occur around midweek.