FORECAST DISCUSSION

SATURDAY 25th APRIL 2026 – P.M SHIFT  

TONIGHT & TOMORROW:

An easterly wind flow remains persistent over Samoa due to a deep layer of high-pressure system near the surface through the levels. However, convection activity observed over the highlands in the afternoon in both major islands resulted from an unstable atmospheric profile aloft and the presence of surface heating. With no other enhancement features in the upper-level, short-lived convection was only experienced with some rainfall activities. Clearing sky cover commenced after sunset, yet, NWP hinted that the speed convergence approaching from the east would increase the chances of cloud development. Therefore, expect to experience cloudy periods early tomorrow morning with some isolated showers and thunderstorms possible.  

SUNDAY THROUGH FRIDAY:

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 & C. BAKER