FORECAST DISCUSSION

WEDNESDAY 29th APRIL 2026 AM SHIFT  

TODAY:

The trade wind weather regime continues to persist across Samoa, bringing few brief showers as observed in parts of the group this morning. The latest satellite data indicate mostly cloud-free conditions over the region, as high-pressure systems remain a dominant weather driver. The morning ascent from Pago (28/12z) reveals strong atmospheric instability, alongside low-level moisture with a precipitable water value reaching 49.23mm. The deepening easterlies are also evident from surface to mid-levels, defining an eastward moisture advection over the region. Upper data indicate a negative vorticity environment and weak to moderate deep-layer wind shear, which may allow some vertical development. However, subsidence aloft continues to persist over the region, significantly suppressing convective storm development and growth for today. Low-level clouds streaming along the easterly flow may bring some showery activity in few areas today; otherwise, fine weather conditions are expected.

THURSDAY THROUGH MONDAY:

Global weather models suggest that the trade wind weather regime will continue through at least Friday. In addition, an elongated surface trough is forecast to move across Samoa from the east on Saturday, bringing rainfall activity through Sunday with the potential for moderate to heavy falls. A surface to mid-level ridge may build from the east and force this low-pressure trough away from the group by Monday, likely resulting in improved weather conditions. The lack of a significant upper-level forcing suggests that convective storms will be largely diurnally driven during this period.

MARINE OUTLOOK:

The latest marine observations from Aunu’u and King Poloa wave buoys indicate that wave heights continue to fluctuate below the advisory threshold of 2.5 metres. Wave watch models suggest that wave activities will persist well below the advisory threshold for the rest of this outlook period.

ADVISORIES/WARNINGS:

NONE

Weather Duty Team:

F. Kalapani, A. Niko, P. Huch & S. Maualaivao.