Area Forecast Discussion
Issued by NWS

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
FXPQ60 PGUM 282025

Area Forecast Discussion
National Weather Service Tiyan GU
625 AM ChST Thu Jun 29 2017

.Marianas Synopsis...
latest satellite imagery showed the upper low moving west of the
Marianas, with abundant clouds and scattered showers for Guam and
Rota. Less showers were observed at this time at Tinian and
Saipan. Additional showers were located south of Guam, north and
east of a tropical disturbance near 4N139E. THe buoys were
generally running between 4 and 5 feet.


Did not make any major changes to the forecast. Scattered showers
seem to be on track at least through tonight and possibly into
Friday, especially for Guam and Rota. However, with rain working
its way up from the south, am a bit concerned that pops could be
too low. Will have to monitor this. Then, showers should become
more isolated until another piece of energy moves through over the
weekend. The models are not in very good agreement with this
possibility with the GFS being stronger and, consequently wetter
than the ECMWF. For now, have left the forecast unchanged. Seas
will remain steady and then slowly decline into next week.


.Eastern Micronesia...
Residual converging winds east of a departing surface trough will
maintain showers near Chuuk today. By this evening, surface ridging
already over Pohnpei should shift westward over Chuuk and promote
more stable conditions. Farther east, a weak circulation and
associated surface trough can be seen extending northeastward from
south of Pohnpei to the Northwestern Marshall Islands. Wet weather
near these features will gradually move westward, reaching Pohnpei
late tonight and Chuuk by Friday evening. With Kosrae remaining
south of the surface trough axis, shower coverage should stay at
isolated category thru tonight. For Majuro, an area of converging
trade winds migrating westward from the Date Line will bring showery
weather by this evening. This same area will also cause wetness to
Kosrae this weekend, Pohnpei and Chuuk early next week.


.Western Micronesia...
Discussion for the Chuuk forecast is included under Eastern

A weak tropical disturbance is seen south of Yap near 4N140E, with a
near-equatorial trough extending westward from it across Koror this
morning. Modest converging winds near the trough will sustain
instabilities near Koror today. Showers and thunderstorms are
forming north of the disturbance near Yap and this trend will
continue thru tonight. This disturbance will slowly track
northwestward late tonight and pass between Koror and Yap on Friday.
Anticipate wetness to linger near Yap thru Friday evening and Koror
thru Friday afternoon. By early Saturday morning, a surface ridge
building westward should introduce partly cloudy skies and isolated
showers to the area. Things might become unstable again early next
week as another surface trough and embedded circulation head this
way from the east.


Marianas Waters...None.


Nierenberg/Chan is the U.S. government's official web portal to all federal, state and local government web resources and services.