Area Forecast Discussion
Issued by NWS Pago Pago

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FXZS60 NSTU 240203

Area Forecast Discussion
National Weather Service Pago Pago  AS
303 PM SST Fri Mar 23 2018

.Short term...
.TONIGHT THROUGH SUNDAY NIGHT...Moderate to heavy mid-morning to
afternoon torrential showers and possible thunderstorms will
dampen most of the forecast zones as a result of strong upper-
level winds combined with dry easterlies and an expected surface
trough through short term. GFS maintains a surface trough well
south of the area while a surface to mid-level ridge from this
morning will linger near the east of Manu`a through the end of the
week. Moisture and rain from the SW will move across the region
later tonight into Saturday. Moderate easterlies will turn
northeast on Sunday then becoming light and variable on Sunday
night. As a result, anticipate humid weather conditions and high
temperatures in the upper 80s to lower 90s, and overnight lows in
the upper 70s to near 80.

.Long term...
.MONDAY THROUGH FRIDAY...A surface trough with several embedded
low pressures will extend to the south of the region past the
midweek. Perhaps this situation will trigger gusty winds, increase
moisture and rainfall to expand across the area...but at 850-700MB,
a strong signature of the ridge axis to the north of Tutuila and
Upolu will extend northwest of the area through long-term. If
models are correct, dry subsidence associated with a surface to
mid-level ridge will block the expected trough from entering the
Samoan Islands. For now, will monitor this situation and provide
updates as future models become available.


.Marine...PACIOOS Buoy near Aunuu shows seas of 6 to 7 ft, which
mirrors expected seas suggested by FNMOC Wave Watch III. A south
swell will arrive tonight through Saturday morning followed by
a northeast swell on Saturday night. Perhaps these swells will
remain below advisory thresholds, but will keep an eye on this
expected event should seas and surfs meet advisory criteria. As a
result, anticipate combined seas of 5 to 7 ft over the next couple
of days.





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