textproduct: WSO Pago Pago
This forecast discussion was created in the public domain by the National Weather Service. It can be found in its original form here.
Discussion
The monsoonal trough that brought nearly three inches of heavy rainfall this morning continues to pose a risk for flash flooding across the area through Saturday. Latest satellite data shows active thunderstorms over Upolu and Savaii, along with cyclonic activity east of Manu'a embedded within the trough. Although low-pressure systems are evident within the trough, no tropical cyclone development is expected at this time. However, model guidance continues to indicate unsettled weather through the end of the week with the trough axis moves over the Islands Thursday This unsettled weather includes: heavy rainfall, flash flooding, possible thunderstorms and winds approaching advisory levels. Widespread showers will persist through Saturday, however, windspeeds are forecast to increase as it turns north-northwest Thursday through Friday. Winds from this direction may strengthen downslope mountains, causing some villages, particularly harbor areas to experience stronger gusts. As we remain within hurricane season, the public is encouraged to stay informed and be prepared, as conditions remain unstable.
By Saturday, a ridge to the east will push the trough southward, resulting in a decrease in shower activity across the territory. Scattered showers with north winds of 10 to 15 mph are expected to persist through Sunday. However, as a ridge of high pressure to the east weakens Sunday night, the trough may shift back over the islands, increasing shower activity once again Monday through the end of the forecast period.
Marine
Latest wave heights observed at the PacIOOS buoys are near 8 feet. Seas are expected to build through Friday as winds increase, with wave heights potentially reaching around 10 feet. Conditions will continue to be closely monitored, as surf may reach warning levels depending on the strength of the winds.
As the trough shifts farther south on Saturday and winds diminish, seas are forecast to subside below advisory levels and remain relatively low into the new week.
PPG WATCHES/WARNINGS/ADVISORIES
Flash Flood Watch High Surf Advisory remains in effect Small Craft Advisory remains in effect
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