FORECAST DISCUSSION

FRIDAY 15thMAY 2026 PMSHIFT

TONIGHT INTO TOMORROW:

The southeasterlies still prevails over the vicinity due to the high pressure system to the west of New Zealand dominates in the region, with fair weather was mostly experienced across Samoa. Except, the satellite data signified afternoon showers mainly over highlands and elevated windward locations. With this, is mainly driven by localized and topographic effects, which was hinted through the sounding profile and total precipitable water animation, revealing low-level moisture content. However, due to the present mid dry slot coincides with the positive vorticity in the upper atmosphere and the strong wind shear environment. Thus, hindering cloud formation to the surface as collectively captured through various satellite channel.

Tomorrow, the weak SPCZ remains to the south, as the persisted mean wind flow is mostly to dominate over the area of responsibility with afternoon convections and a few possible thunderstorms that aligned with diurnal weather patterns.

SUNDAY THROUGH THIURSDAY:

Numerical weather predictions, forecasted rainfall activities on Sunday through Monday, as the previously stated high pressure continues to move eastward, shifting the weak SPCZ slightly to the south of Samoa. In this period, persisted wind flow will swerve from the east-to-northeast then northerly on Tuesday as a pronounce circulation over Fiji, while tracking southeastward with some intensity, but poses no direct threat to Samoa. As it continues this system’s course, the wind flow would become northwesterlies on Wednesday through Thursday, with showery and thundery activities are mainly driven diurnal variation atmospheric condition.

MARINE OUTLOOK:

As of now, marine wave observations at the southern waters signified wave and swell heights fluctuated at the range of 2-2.5 metres. However, a high pressure system stationed to the west of New Zealand gradually move to the east, while bringing elevated waves and high swell that could impact Samoa’s southern marine areas by tomorrow night. In addition, these wave activities are expected to coincides with the highest tide of May on Sunday at 06:10 am, causing wave heights to exceed 2.5 metres.  Henceforth, the above-highlighted advisory remains enforced for the southern marine waters.

ADVISORIES/WARNINGS:

VALID: MARINE ADVISORY – SOUTHERN MARINE WATERS

Weather Duty Team:

A. Liu, A. Sofeni, & F.U. Namulau’ulu.