FORECAST DISCUSSION

SUNDAY 26th APRIL 2026 – A.M SHIFT  

TODAY:

An intense high-pressure system centred east of New Zealand continues to direct east to southeasterly winds, becoming fresh at times across the Samoan group. This weather pattern advect cool and dry wind flow over the region. The water vapour satellite imageries also signify drier airmass at the uppers as a high pressure predominates, directing southeasterly aloft. The weak winds from mid levels through the uppers lead to a weak shear environment over the region. But for today, orographic lifting may trigger cloud developments mostly over highlands in the afternoon, although clouds will not be convective as they will be greatly suppressed jointly with drier conditions. Thus, light showers may be observed in some areas, otherwise mostly fine.

MONDAY THROUGH SATURDAY:

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:

A.N, S.K, F.U.N & A. Uili