SYNOPTIC DISCUSSION

TUESDAY 27TH JANUARY2026 AM SHIFT

TODAY:

Cloudy and moist conditions dominate the area as the convergence zone remains located North of the group. CIMMS observations show favourable mechanisms for convection throughout the depth of the atmosphere. Weather charts analysed a circulation south of Samoa also the Himawari heavy rainfall potential synthetic satellite data hints deep convections circulating the forecast zone, with most of the well-organised rain bands to the northwest and eastern parts of the island chain. Severe weather guidance update favours our forecast area for heavy rain, strong wind waves. However, confidence level reduces towards the last days of the outlook. Models suggest potential for unsettled weather conditions to persist for the rest of today. Therefore, expect isolated showers with periods of heavy falls, thunderstorms and gusty winds at times.

WEDNESDAY THROUGH MONDAY:

Global weather models suggest that moist and unstable atmospheric conditions will persist over Samoa throughout this outlook period, with the South Pacific Convergence Zone (SPCZ) remaining the primary weather driver. A broad area of low-pressure may persist just south Samoa, triggering the formation of embedded low circulations to the south through southeast of the group. This broad area of low-pressure is likely to maintain abundant moisture advection over the region, accompanied by strengthening northwesterly wind flow. Model consensus suggest a southward movement of the SPCZ by mid-week, intensifying deteriorating weather through 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 maintaining 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:

A.N, L. T & A. UILI