FORECAST DISCUSSION

SUNDAY 26th APRIL 2026 – P.M SHIFT  

TONIGHT & TOMORROW:

Dissipating cloud development began to be observed in the afternoon on both satellite imagery and surface observations, while the easterly flow remained in control of the weather. The intense high-pressure system located to the west of New Zealand remains the dominant weather feature over Samoa. Sounding data from Pago showed an inversion layer near the surface, which inhibited convection despite the availability of near-surface moisture. Winds strengthen slightly across the island, which tends to create some wind convergence, however, without any other supporting mechanisms, this resulted in minimal rainfall activity. Models continue to indicate that the easterly wind flow will persist over the forecast area through tomorrow, with a lower chance of major thunderstorms. Therefore, expect partly to cloudy periods with brief showers.

TUESDAY 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 later in the week 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:

LMSA, A. SOFENI & P. HUCH