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 17 18
FXPQ60 PGUM 221955

Area Forecast Discussion
National Weather Service Tiyan GU
555 AM ChST Sun Jul 23 2017

.Marianas Synopsis...
Early morning radar imagery showed isolated showers generally
east of Guam and a larger area of showers southeast of Guam.
Otherwise, scattered clouds were evident on satellite and combined
seas were generally between 2 and 3 feet.


Increasing moisture today and Monday, mainly at the midlevels will
bring a chance of afternoon thunderstorms. Depending on how things
develop, pops may need to be marginally increased. Otherwise, no
changes were made to the forecast. After Monday, drier air moves
back in, and expect a relatively dry period into next weekend.
The Marianas will be between a slow moving tropical storm well to
the north, the monsoon trough to the west and northwest and
several disturbances staying to the south over Micronesia. Wind
should gradually shift from easterly trade to southeast then south
and eventually southwest, but at least for the balance of the
week, should be relatively light.


.Eastern Micronesia...
An overall unsettled pattern is expected to continue from Chuuk
eastward to Majuro through most of this week. The latest time/height
products show a fairly moist pattern for all 3 forecast points. With
weak low-level convergence remaining over the area along with weak
disturbances transiting the region, isolated showers and
thunderstorms are expected to continue through at least Thursday.
Short periods of scattered showers remain a possibility. An enhanced
area of convergence to the southeast of Majuro is responsible for
scattered showers and a few thunderstorms over that area. This band
will approach Majuro through the day, bringing scattered showers to
the atoll later this evening.


.Western Micronesia...
Chuuk reasoning is included in the Eastern Micronesia discussion

The monsoon trough and a weak disturbance northwest of Koror are the
primary concern over Koror an Yap for the next day or two. The
disturbance is now farther northwest, though still close enough to
Koror and Yap to produce increasing showers through Monday night.
Latest model guidance shows the likelihood of numerous showers
beyond Monday afternoon is very limited, along with weaker winds
expected as well as the circulation moves farther away. A band of
numerous showers to the east of Koror is slowly approaching the
island and is expected to reach there late this morning or early
afternoon. These showers could produce heavy rain at times. Model
guidance does show a fairly moist pattern continuing through the end
of the week as the monsoon trough remains over the area. It now
appears likely that the numerous showers will be short-lived and
likely decrease to scattered by this evening. Shower coverage is
then expected to decrease to isolated Tuesday through the end of the

As the disturbance continues toward the northwest, winds and swell
are likely to increase to levels hazardous to the operators of small
craft tonight through Tuesday at Koror, remaining just below
hazardous levels for Yap. As southwest swell increases over the next
12 to 24 hours, hazardous surf also becomes a possibility at both
locations for south and west facing reefs.


Marianas Waters...None.


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