Area Forecast Discussion
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FXPQ60 PGUM 190809

Area Forecast Discussion
National Weather Service Tiyan GU
609 PM ChST Fri Jan 19 2018

.Marianas Synopsis...
Andersen Air Force Base Doppler weather radar shows only a few
showers within the Marianas waters, with isolated showers just
south of the Guam coastal waters. The VAD wind profile indicates
east-northeast winds of 12 to 20 knots through the lowest 4
thousand feet of the air. The buoys reveal combined seas of 6 to 7


The Marianas and surrounding coastal waters remain entrenched in a
dry trade-wind regime. GFS sees little change in this through
Wednesday, while the ECMWF sees little change through the entire
week. Satellite shows little in the way of clouds to our east, so
left the dry and relatively sunny forecast intact. Just refreshed
the winds and the waves. ASCAT analysis shows a trough just east
of the Marianas, even this is currently not producing much
precipitation at this time.


Tabular wave guidance shows 6 to 7 foot combined seas continuing
through Sunday, then they should increase. Buoys indicated that
surf of 9 feet is still possible on east facing reefs, so extended
the high risk of rip currents. Since, after Sunday, the waves
increase further, extended the risk through day 6. The risk could
possibly slip to moderate for a short time, then we would just
have to ask whether or not it would be worth canceling for a short
time when it is quite marginal and east reefs are among the most
dangerous at any time. With it being marginal even on the east
reefs though, did not extend it around to north reefs.


.Eastern Micronesia and Chuuk...
A trade-wind disturbance with showers and a few thunderstorms over
Kosrae State and the western Marshall Islands is moving west into
Pohnpei State this afternoon. The showers will continue westward
across Pohnpei and Chuuk this weekend. Weather has already improved
at Majuro, and gradually improving weather is expected behind the
disturbance as it moves farther west. Trade-wind convergence will
likely trigger spotty showers over the region thru next week, except
very dry weather is developing over far northern Marshall islands.

A marginal Surf Advisory remains in effect for east facing shores of
Kosrae, but surf could drop below hazardous levels this weekend.


.Western Micronesia for Yap and Koror...
An area of showers and thunderstorms moving across Yap is edging
toward Koror this afternoon. ASCAT analysis shows another surface
trough and weak circulation near 2N135E remain nearly stationary
across southern Palau. As the area of showers moves farther west,
weather should improve at Yap and Koror on Saturday, then models
indicate fairly strong low-level convergence developing across the
area will trigger more showers through early next week, especially
at Yap.


GU...High Rip Current Risk through Thursday afternoon for GUZ001>004.
     Fire Weather Watch through Monday evening for GUZ001.

Marianas Waters...None.


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