FORECAST DISCUSSION
SATURDAY 18th APRIL 2026 – P.M SHIFT
TONIGHT:
The weak South Pacific Convergence Zone (SPCZ) has slightly relocated south as the ridge of high pressure strengthened by the easterlies persist. Remnants of the system has availed lingering instability which brought about cloudiness, observed earlier in the day. Sounding profile of the atmosphere indicated moisture accumulation to the south, while there was existing moisture over the group – the existing upper level convergence which aided the restriction of cloud growth and rainfall activity. Therefore, anticipate fewer clouds content with fewer showery activities for tonight and tomorrow – whereas rainfall may be localised and restricted in the late morning towards the evening – enhanced by surface heating.
SUNDAY THROUGH FRIDAY:
A high-pressure system currently centred east of Australia is expected to move eastward, forcing the South Pacific Convergence Zone (SPCZ) eastward and away from the group. This synoptic weather pattern may allow the easterly trade wind regime to predominate throughout the week. At mid-levels, a high-pressure ridge may linger over the region during this outlook period, providing light steering flow, which suggests a lack of vertical disruption to convective development. In addition, westerly to southwesterly winds aloft are forecast to dominate the uppers through at least Monday, before an upper high develops over the region. Models also hinted a weak short-wave trough embedded along the easterly flow on Tuesday and Wednesday, which may bring some showery conditions across the group.
MARINE OUTLOOK:
The latest marine observations from Aunu’u and King Poloa wave buoys as well as altimeter data indicate that wave heights have fluctuated below 2 metres over the past 24 hours. These wave activities are forecast to persist throughout this outlook period, posing no significant wave-related hazards to the islands’ marine waters.
ADVISORIES/WARNINGS:
NONE
Weather Duty Team:
MJS, Andrew Sofeni, Aquinas Uili & Fuimaono Uili Namulauulu.