FORECAST DISCUSSION

TUESDAY 28th APRIL 2026 – A.M SHIFT  

TODAY:

The latest satellite data indicate occasional convection further south of Samoa, which is associated to the suppressed South Pacific Convergence Zone. The easterly trade wind weather regime continues to persist across Samoa, resulting in fine weather across the group. Data from the ascent from Pago (27/12z) reveals good atmospheric instability and a dry vertical profile with precipitable water reaching 46.85mm. In addition, subsidence aloft persist over the forecast area as high-pressure systems dominate the mid and upper level atmosphere. Therefore, expect periods of partly cloudy skies with a chance of a few thunderstorms in the afternoon.

WEDNESDAY THROUGH SUNDAY:

Global weather models suggest that the trade-wind weather regime will persist across Samoa throughout this outlook period. A high-pressure system is expected to dominate the mid-levels, maintaining an easterly steering flow. The lack of a significant upper-level forcing mechanism suggests that cloud development will be largely diurnally driven during this outlook period. This synoptic pattern may induce a relatively dry airmass and subsidence aloft over the region, which may inhibit significant convective storm development and growth. NWP indicated a surface trough to migrate near the forecast zone over the weekend which may induce rainfall activities, however, high uncertainty for the meantime.

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. The 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:

A. Niko, S. Kalolo, S Maualaivao & F.U. Namulau’ulu