SYNOPTIC DISCUSSION

MONDAY 30th MARCH 2026 PM SHIFT

TONIGHT INTO TOMORROW:

As of now, the active trough of low pressure embedded within the SPCZ still linger within the vicinity. Based on the sounding profile indicated sufficient moisture mainly at the low levels, mid-to-upper tropospheric dry slot, and instability. Also, the relative vorticity fields at the (850-700) hPasignified cyclonic anomalies, an implication of vertical cloud formation from the surface. In the upper atmosphere, consist of a upper trough of low pressure generating upper divergence with weak wind shear, supporting the surface system. Which, the satellite data indicate cloudy conditions that generate brief heavy falls in some areas, a few thunderstorms and gusty periods. The model consensus, that the system slowly move to the south, while maintaining unstable weather pattern, a slight increase in wind strength that likely affect windward locations.

WEDNESDAY THROUGH SUNDAY:

Global weather models suggest that the South Pacific Convergence Zone (SPCZ) will remain stationary just north of Samoa through Tuesday, then move over the group by Wednesday. This synoptic weather pattern may maintain unsettling weather conditions over Samoa with the potential for heavy downpours and thunderstorms during this period. The movement of the SPCZ over the group is expected to induce strengthening northerly winds on Wednesday where wind speeds range from 20-25 knots. By Friday, the trade wind weather regime is expected to predominate through the end of this outlook period, bringing improved weather conditions across the group. In addition, a weak upper trough may influence the group through at least Tuesday, and with the lack of a significant upper-level system, cloud development will be largely diurnally driven during the remainder of this outlook period.

MARINE OUTLOOK:

Generally, the marine observational data continue to revealed that the wave activities across Samoa’s marine areas remain below the 2.5 meter threshold, which poses no threat. This wave trend is forecasted by the global wave model to persist throughout the forecast period.

ADVISORIES/WARNINGS:

VALID: HEAVY RAIN WARNING

VALID: FLOOD WARNING

Weather Duty Team:

A. Liu, A. Niko, N. Tutasi, & F.U. Namulau’ulu.