textproduct: WSO Pago Pago

Long term [Saturday through Wednesday]

A pattern shift is expected this weekend as a low to mid-level shortwave trough is forecast to develop over the territory. This mid-level trough should increase rain chances throughout the weekend.

The trough is forecast to peak in intensity on Sunday, bringing potential for heavy rainfall and possible thunderstorms in the area. While there is high confidence in timing, there is still considerable uncertainty regarding intensity of the trough when it peaks over the area on Sunday. The operational GFS is the strongest depiction of the trough out of our model suite. The last several runs of the GFS depict strong low-level winds working their way down to the surface on Sunday. This GFS solution would bring breezy conditions that near Wind Advisory threshold on Sunday, especially for the Pago Pago Harbor region due to northerly flow interaction with terrain. Other model and ensemble data still bring increased northeasterly flow, but keep wind speeds well below advisory threshold.

The trough is anticipated to weaken over the area by the new week. Easterly winds should take over, driven by high pressure building to the southeast. Any showers embedded within the easterly flow are expected to come in the passing form.

Marine

Seas have been observed at around 6 feet throughout the day at Aunu'u Buoy. Light to moderate winds should hold similar ocean conditions through Saturday. The aforementioned trough is expected to bring a fresh breeze by Saturday night, which may further increase to a strong breeze on Sunday depending on the strength of the trough. Regardless, seas are likely to build to Advisory levels over this period.

PPG WATCHES/WARNINGS/ADVISORIES

None