Area Forecast Discussion
Issued by NWS Pago Pago

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FXZS60 NSTU 170111
AFDPPG

Area Forecast Discussion
National Weather Service Pago Pago  AS
211 PM SST Sat Dec 16 2017

.Short term...
TONIGHT THROUGH MONDAY NIGHT...Latest satellite imagery shows the
active Tropical Disturbance 02F (TD02F) about 215 miles Southwest
of Tutuila. Current model data is consistent with moving TD02F
Eastward, toward Tutuila Sunday, then will change course and move
Southeast. Model data shows TD02F intensifying, reaching Tropical
Depression level winds when it is closest to Tutuila Sunday
afternoon, then quickly subsiding Sunday night as it veers toward
Southeast. A new solution that diverges from previous ones show
another low developing within the active South Pacific Convergence
Zone (SPCZ) just north of the Samoan islands Sunday night.
Current models do not show this second low intensifying to
Tropical Depression levels. However, it does show it bringing more
showers with embedded thunderstorms across the territory Monday
night. Hence, the potential for flash flooding with SPCZ lingering
near the Samoan islands and the developing lows will remain
through at least Monday.

.Long term...
TUESDAY THROUGH SATURDAY...The aforementioned second low moving
across the islands from the north will drag the SPCZ across the
Samoan islands through Wednesday. Hence, expect the potential for
flash flooding to remain Wednesday. Current model data show the
SPCZ still lingering across the area, but most of the rain will be
concentrated to the West. For now, as model skills tend to
diminish greatly after day 3, will continue previous forecast for
American Samoa.

&&

.Marine...
Current PacIOOS Aunuu wave buoy show observations exceeding
advisory criteria this afternoon. Latest Wave Watch III/SWAN model
output are in consistent with previous solutions, showing a rapid
increase in heights due to the anticipated evolution of Tropical
Disturbance 02F by Sunday. This will likely prompt an upgrade in
the High Surf Advisory to a Warning. For now, due to the seas as
well as the anticipated increase in winds starting tonight, the
advisories for small crafts and high surfs are now in effect.

&&

.PPG WATCHES/WARNINGS/ADVISORIES...
Flash Flood Watch Remains in effect
Small Craft Advisory is in effect
High Surf Advisory is in effect

&&

$$

ELM



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