textproduct: WSO Pago Pago

DISCUSSION

A low pressure system to the southeast continues to migrate further east as it pulls the trough line away from area. However, unstable conditions remain over the territory as the trough continues to produce widespread showers with possible thunderstorms. Also favorable in producing heavy showers and gusty winds from time to time are the single cell convections embedded within the trough line. Winds will remain light and variable for the short term forecast period, except during heavy showers and nearby thunderstorms. These conditions are further supported by the latest satellite imageries and upper air observations (RAOB) from this afternoon (27/00Z). A moist atmosphere with thunderstorm signals and strong upper level winds conducive of severe weather patterns. Therefore, the threat of flash flooding and landslides is possible as grounds have been saturated through at least midweek.

Model data projects improving conditions starting late Wednesday through the rest of the forecast period. As the aforementioned trough moves out of the area, a high pressure system to the south will generate moderate east-southeasterlies with embedded showers on Friday night through the end of the long term period. No imminent threat is expected for the rest of the forecast period.

Marine

Rough seas continue to linger over the American Samoa coastal waters for the last 12 to 24 hours. Data from the PacIOOS buoy data near Aunu'u show wave heights remaining in the advisory thresholds. However, model data shows a downward trend starting tonight and remaining through at least Friday. By Friday night, models are showing another large south swell with long periods peaking at 15 seconds reaching the south facing shorelines and remaining through the end of the forecast period (5 days out). The long periods will likely enhance strong rip currents and higher surfs. Thunderstorms embedded within the aforementioned trough will produce gusty winds from time to time, and elevate seas nearby. Otherwise, light and variable winds are projected to remain over the area tonight through at least Friday morning. These winds will increase to gentle and moderate easterlies by Friday night through the end of the period. The threat of high surfs and strong rip currents remain over the area.

PPG WATCHES/WARNINGS/ADVISORIES

High Surf Advisory Small Craft Advisory Flood Watch