SYNOPTIC DISCUSSION

WEDNESDAY 28THJANUARY 2026 AM SHIFT

TODAY:

Developing clouds and showers associated with the SPCZ lies slow moving within the vicinity of Samoa. Heavy down poured and gusty wind conditions experienced earlier this morning mainly to Northern locations an indication of the southward movement of the SPCZ. A strong upper divergence has shifted just to the North of Samoa enhancing surface convections. MMIC and total precipitation clearly displayed an abundant moisture over the country. This to couple with an unstable vertical profile of the atmosphere likely to contribute with major rainfall activities within the now cast period. In terms of surface analysis, a broad area of low pressure system lies to the south of Samoa creating favourable surrounding environment for cloud development. Models suggested rainfall activity and gusty condition to persist throughout today.

THURSDAY THROUGH TUESDAY:

Moist and unstable weather conditions are forecast to remain over Samoa throughout this outlook period, with the South Pacific Convergence Zone (SPCZ) being the primary weather driver. The embedded low circulation developments to the south of the group may maintain abundant moisture advection over the region, accompanied by deepening warm and moist northwesterly winds. A strengthening ridge of high-pressure may build from the north, pushing convective activities just north of Samoa before completely residing over the group by Saturday. Global weather models suggest that deteriorating weather will gradually intensify into the weekend; however high uncertainty for the meantime. The interaction between the MJO and upper-level dynamical enhancement is likely to sustain the activeness of the SPCZ throughout this outlook period

MARINE OUTLOOK:

The latest wave observations from Aunu’u and King-Poloa buoys, as well as altimeter data, signify wave heights exceeding 2.5 metres. This is mainly due to the convergence zone directing fresh and gusty westerly winds and thus maintain elevated wave activity over our marine waters. The global wave models suggest this weather system to maintain these high wave activities over the forecast area throughout the week.

ADVISORIES/WARNINGS:

VALID: HEAVY RAIN WARNING

VALID: FLOOD WARNING

VALID: WIND ADVISORY

VALID: MARINE ADVISORY

Weather Duty Team:

LMSA, L.I.TUATIPI & P. HUCH