Area Forecast Discussion
Issued by NWS Tiyan, Guam

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FXPQ50 PGUM 072144

Area Forecast Discussion
National Weather Service Tiyan GU
744 AM ChST Wed Apr 8 2020

.Marianas Synopsis...
Satellite shows a disturbance bringing increased cloudiness to the
Marianas, especially north of Saipan. So far there do not seem to be
many showers, as all the cloud top temperatures are above freezing.
The buoys reveal combined seas of 4 to 6 feet, composed mainly of a 2
to 3 foot north swell and a mix of east trade-wind waves and swell.


Overall, the Marianas remain anchored within a rather dry trade-wind
pattern. This pattern is punctuated by occasional disturbances, one
of which dumped a fair amount of rainfall on the Guam airport. That
area was highlighted by some significantly cooler cloud tops, and in
this case, and the case of the disturbance expected for Thursday, we
are seeing little if any such enhancement. Therefore, am expecting
that the next few days will continue the general dry trend. There
will be an increase in clouds however, and with the current
disturbance already overhead, pulled that cloudiness from tonight
into today as well. Went ahead and repopulated the wave grids, mostly
to extend them. The general trends did not change, elevated wave
activity through Friday, then it diminishes. We could even reach a
low risk of rip currents early next week. In the meantime, however,
we could briefly touch high risk on Thursday. For now, kept the
forecast at the upper end of moderate.


.Fire weather...
A wetting rain on Sunday eased the fire danger. With expected dry
weather though, it will start creeping back up. In a few days, it
looks like the winds will diminish. This might be what prevents any
further critical fire weather days.


.Eastern Micronesia...
A surface trough extends northeastward from south of Kosrae through
Majuro to end around 10N175E. Deep convection is firing up near this
trough and farther west to the south of Pohnpei.

Majuro is in a clear slot this morning but a round of showers is
possible as the surface trough lingers overhead. The trough will push
westward tonight, introducing fair weather to Majuro on Thursday.
Unsettled weather is still on tap for Kosrae the next several days as
convergent trade flow persists. This should come as no surprise
since April is usually the rainiest month of the year for Kosrae.
Showers increase at Pohnpei on Friday as the trough nears and low-
level convergence settles in behind it. Cloudier weather and showers
may approach Majuro on Saturday as the ITCZ noses in from the east.

Marine conditions have improved at Majuro with fresh northeast winds
retreating to the north. Maintained a headline for the possibility
of minor inundation at Majuro today based on high astronomical tides,
longer-period northeast swell and lingering short-period northeast
swell. If inundation does not occur today the threat will diminish.
Tropical Cyclone Harold in the Southern Hemisphere will continue to
generate S swell. This will keep surf elevated along S to SE reefs
through early next week.


.Western Micronesia...
Partly cloudy skies and gentle to moderate trade winds prevail at
Palau, Yap and Chuuk this morning. ASCAT shows a weak circulation
along the equator southwest of Chuuk near 148E. Palau may see an
increase in showers later today as a weak area of trade convergence
drifts overhead. The weak circulation near EQ148E will drift westward
the next few days, with showers developing in convergent flow to the
north of it. This feature could bring much-needed showers to the
islands of Yap state but confidence is not particularly high. If the
circulation hugs the equator, as suggested by the ECMWF, most shower
activity would remain south of Yap. This disturbance may boost
showers across Palau late this week as well, especially if the
circulation drifts more westward than northwestward. Seas are still
forecast to gradually subside as upstream trade winds weaken further.


Marianas Waters...None.


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