SYNOPTIC DISCUSSION
SUNDAY 01st MARCH 2026 AM SHIFT

TODAY:

A ridge of high-pressure was analysed over Samoa, directing moderate northeasterly winds across the group. The system extends through the mid-levels and is gradually inducing stable atmospheric conditions over the region, while keeping the SPCZ displaced further south. The morning ascent from Pago (12z) indicates dry slots in the lower and upper levels of the atmosphere, with deepening northeasterlies advecting marginal moisture across the group. MIMIC Total Precipitable Water (TPW) imagery reveals abundant moisture feeding into Tropical Cyclone Urmil (CAT2), currently positioned southwest of Fiji. CIMSS data indicate a lack of significant lifting over the forecast area with a strong deep-layer wind shear environment. The persistence of strong southeasterly winds aloft may steer some upper-level clouds over the group, while approaching patches of low clouds could bring some showers in parts of Samoa today. In addition, local effects may trigger a few thunderstorms today, particularly over highlands and may bring brief moderate to heavy falls in some areas with gusty winds at times.  

Tropical Cyclone Urmil (CAT 2) is currently located southwest of Fiji, approximately 1,231 km southwest of Apia. This system poses no threat to Samoa. TC Urmil is forecast to maintain its southeastward movement while gradually weakening over the next 12-24 hours, as it moves into unfavorable atmospheric environment.

MONDAY THROUGH SATURDAY:

Global weather models suggest that the abovementioned high-pressure ridge will move southward by Tuesday, allowing the easterly trades to dominate through at least Thursday. This synoptic pattern may maintain the SPCZ further south of Samoa throughout this outlook period. As a result, trade wind showers with afternoon convections will be the primary rain maker; otherwise, mostly fine weather is expected during this period. Although a probable upper-level trough may lingers over the group by mid week, instability and moisture areas are hinted further south along the SPCZ chain. In addition, a surface trough is forecast to move over the group on Friday and is likely to bring increasing showery conditions across the islands.

MARINE OUTLOOK:

The latest marine observations indicate that wave and swell heights continue to fluctuate at 2 meters, suggesting no imminent threat across Samoa’s marine areas. Global wave models suggest that wave activities will persist below the advisory threshold of 2.5 metres throughout this outlook period.

ADVISORIES/WARNINGS:
NONE

Weather Duty Team:
Kalapani, Tuatipi, Huch & Tavanā.