FORECAST DISCUSSION

MONDAY 20th APRIL 2026 – P.M SHIFT

TONIGHT AND TOMORROW:

Predominantly, the moist easterly winds persist over the group, accumulating showers over mountain ridges and especially over the windward locations of both main islands. However, the latest satellite has indicated an approaching surface short-wave trough riding the easterlies; therefore, this now aids the development of cloud coverage, possible isolated showers, and a slight chance of thunderstorms. The movement of the system is now driven by the deepening easterlies and a deepening ridge in the mid- to upper atmosphere, maintaining the descent of the system. Therefore, anticipate conditions becoming cloudy with brief isolated showers and a chance of thunderstorms.

TUESDAY THROUGH SUNDAY:

Global weather models suggest that the easterly trade winds will predominate the region throughout this outlook period. An embedded weak short-wave trough at the surface may move across the group on Tuesday, likely bringing some showery conditions. The trades may persist at gentle to moderate intensity throughout the week, with a fresh wind surge entering the forecast area by Saturday. In addition, high-pressure systems are forecast to dominate the mid and upper levels during this period, suggesting subsidence aloft, which may inhibit widespread significant convection over the region. Therefore, mostly fine weather is expected across the group, apart from possible localised afternoon thunderstorms over the interior highland areas.

MARINE OUTLOOK:

The wave watch model predicts wave activities ranging well below the advisory and warning thresholds for the rest of the outlook period. Recent observations across the group’s coastal and marine waters indicate non-significant wave activity and may remain so, as mentioned above.

ADVISORIES/WARNINGS:

NONE

Weather Duty Team:

MJS, Sasamamao Kalolo Lemauga, Christopher Baker & Samuelu Tavana