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Displaying AFOS PIL: AFDPPG Product Timestamp: 2018-02-09 02:03 UTC
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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