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485 
FXZS60 NSTU 090204
AFDPPG

Area Forecast Discussion
National Weather Service Pago Pago  AS 
Issued by National Weather Service Honolulu HI 
303 PM SST Thu Feb 8 2018

.Short term...
.TONIGHT THROUGH SATURDAY NIGHT...A developing tropical cyclone (TD 
07F/97P) is currently centered near Wallis and Futuna, or about 400 
miles west of Tutuila, and is heading toward the east. This system 
is expected to pass very close to Tutuila and Manua on Friday, 
bringing strong and potentially damaging winds, as well as 
torrential rain and treacherous marine conditions. Although the 
satellite presentation of the system is thus far not typical of a 
tropical cyclone, strong monsoon westerlies are noted north of the 
developing low and associated trough. Recent ASCAT data showed a 
swath of 30-40 kt winds, with pockets of 50 kt, within the area 
north of what appears to be a consolidating low-level circulation 
center. With all forecast models indicating a track near or just 
south of Samoa Friday, weather conditions are expected to 
deteroriate overnight as strong monsoon westerlies and associated 
heavy rains/thunderstorms move over the region. The center of the 
system is expected to pass close to Samoa on Friday, and then move 
southeast away from the area. 

However, the potential for additional heavy rain and strong monsoon 
winds will continue through Saturday, as another tropical 
disturbance (TD 08F/98P), currently south of Fiji, moves closer. 
Although the specifics of the forecast tracks of the two cyclones 
remains uncertain due to potential interactions between the two, 
there is increased confidence in a prolonged period of wet monsoonal 
flow, with especially active weather on Friday and again on 
Saturday. 

.Long term...
.SUNDAY THROUGH THURSDAY...A wet and windy monsoonal flow will 
continue through Monday as west to northwest winds are expected to 
prevail, bringing periods of heavy showers and thunderstorms, and 
occasionally strong gusts. Winds are expected to diminish Tuesday 
and Wednesday potentially becoming light and variable by Thursday, 
with decreasing showers also expected. 

&&

.Marine...Latest Wave Watch guidance brings extreme wave heights to 
the area on Friday and Saturday as two tropical cyclones pass close 
to the area. While seas may not get as high as indicated by the 
guidance, winds, seas and swells are expected to be dangerously high 
and marine travel should be postponed until winds and seas diminish 
early next week. Small craft should remain in port. Extremely high 
surf is likely to build along north and west facing shores and 
reefs, and a High Surf Advisory is in effect. 

&&

.PPG WATCHES/WARNINGS/ADVISORIES...
.Tropical Storm Watch for all of American Samoa.
.Gale Warning for Swains through Friday.
.Wind Advisory for Swains.
.Flash Flood Watch through 3 PM SST Sunday. 
.High Surf Advisory. 
.Small Craft Advisory for Tutuila, Aunuu, Manua. 
.Special Weather Statement. 

&&

$$

Birchard