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FXPQ60 PGUM 210947

Area Forecast Discussion
National Weather Service Tiyan GU
747 PM ChST Tue Nov 21 2017

.Marianas Synopsis...
Andersen Air Force Base Doppler weather radar shows isolated
showers moving through the Marianas waters. The VAD wind profile
shows northeast winds of 10 to 15 knots through the lowest 8
thousand feet of the air. The buoys reveal combined seas of 5 to 7


The Marianas have fallen into a rather dry trade-wind regime,
perhaps a harbinger of the coming dry season. Major change to the
forecast was, based on even a further dwindling of support in the
time height and satellite plus lightning data, took out the
mention of thunderstorms Wednesday night and Thursday. Left the
mostly cloudy intact as there could still be an increase in
clouds, expect the increase to be rather underwhelming though.
Around the weekend winds are expected to increase, went ahead and
called for breezy conditions. Overall, not much to write about.


In response to the increasing winds mentioned above, seas will
build over the weekend also. They could even challenge small craft
advisory criteria, and a high surf advisory is not out of the
question either. This is the time period that will probably need
the most watching this week.


.Eastern Micronesia...
A tropical disturbance/weak circulation remains in the region, now
SSE of Chuuk near 5N155E. Scattered showers and isolated
thunderstorms are primarily confined close to the circulation
itself while widely scattered showers are farther north along a
trough axis extending to the north near Chuuk. Isolated trade wind
showers are present elsewhere across the region. A weaker
circulation is found NE of Majuro and is expected to weaken
tonight and tomorrow into an open- wave trough. Only minor tweaks
more made to the regional forecasts through the weekend. Primary
focus will be on the wet pattern at Chuuk the next few days.
Unsettled conditions will persist there with moderate to fresh
trades near and north of Chuuk and gentle to moderate winds to the
south. Expect periods of isolated to scattered showers the next
few days. Relatively drier weather is expected elsewhere across
the region. A surface trough may bring more showers to Majuro and
Kosrae by the weekend.


.Western Micronesia...
A surface trough extends eastward through 4N130E to near the weak
disturbance SSE of Chuuk. Moderate to fresh trades converging north
of the trough axis are generating showers and thunderstorms south of
Yap and Koror. Moderate to fresh trades will persist the next few
days with lighter winds south of Yap and Koror. An unsettled weather
pattern will persist along this boundary the next several days
keeping showers and thunderstorms primarily close to Koror...but
just south of Yap.

Will continue to keep a close watch on the circulation SSE of Chuuk
the next few days. Models still show no development with this system
with it eventually weakening into an open-wave trough, but it could
still bring more showers to the region later this week as it passes
by to the south.


Marianas Waters...None.


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