Area Forecast Discussion
Issued by NWS Pago Pago

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FXZS60 NSTU 200109

Area Forecast Discussion
National Weather Service Pago Pago  AS
209 PM SST Fri Jan 19 2018

.Short term...
.TONIGHT THROUGH SUNDAY NIGHT...An upper-level trough will remain
nearly stationary above the Samoan Islands through Saturday. This
weather phenomenon combined with low-level convergence will generate
scattered to frequent thunderstorms and numerous showers through
Sunday night. GFS models and SWFDDP (Severe Weather Forecasting
and Disaster Risk Reduction Demonstration Project) guidance agree
to bring heavy rainfall around the region during the next few days
prior to the arrival of a surface trough near east of Manu`a on
Sunday morning. The upper-level trough axis will slide southward
then southwestward starting Saturday afternoon into Sunday. However,
warmer temperatures and humid conditions will coexist with the
expected shower coverage at scattered to numerous showers through
short term.

.Long term...
.MONDAY THROUGH FRIDAY...A surface trough to the southwest of
Tutuila and Upolu combined with low-level convergence will provide
scattered showers and possible thunderstorms during Monday and
Tuesday. GFS models show a lot of uncertainties after Tuesday
afternoon. Thus, will keep the previous forecast the same except
to update the temperature parameter.


.Marine...The PACIOOS Buoy near Aunuu shows sea heights peaking to
near 10 to 11 feet this afternoon, to which FNMOC Wave Watch III
fails to identify on current model runs. A south swell combined
with strong gusts associated with scattered thunderstorms around
the Samoan waters will produce hazardous sea conditions through
Saturday evening. These expected swells will subside to near 5 to
7 feet during Saturday night and Sunday morning. There are no
significant swells expected after Sunday afternoon.


.A High Surf Advisory.
.A Small Craft Advisory.



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