SYNOPTIC DISCUSSION
TUESDAY 25th MARCH 2025 PM SHIFT.
TONIGHT INTO TOMORROW:
A collection of satellite imagery shows that the convergence lies over the vicinity of Samoa. The system brings a significant amount of moisture content, as depicted by the total precipitable animation. Also, the scatterometer swaths showcase the system induces 15-20 knots, positioned slightly south of the area of responsibility. Further, an area of upper diffluence situated to the south generated a weak divergence region that stretches over Samoa and supports the surface system. Hence, the advisory level for heavy rain and flooding remained at all levels of the country.
For tomorrow, the convergence zone along the dominated wind flow slowly dissipates, yet the moisture content still lingers over the atmosphere. Towards the afternoon, there is a low-to-moderate chance of afternoon convections aided by surface heating and orthographic lifting over the highland. So, expect cloudy periods with some isolated showers. Brief heavy falls in some areas and a few thunderstorms.
On the other hand, a trough of low pressure could be visible later tomorrow approaching from the North of Samoa. The system, sustains the equatorial flow over the islands, with wind strength to be calm-to-gentle. Wind directions are expected to slowly swerve northeast.
THURSDAY THROUGH MONDAY:
Global weather models generally suggest, a minimum precipitation amount throughout the outlook period. A trough of low-pressure system may closely located North of Samoa on Thursday. It may move over the area of interest on Friday as the wind direction becomes northeast, ushering warm and moist equatorial flow. Thus, such expected weather conditions triggered afternoon convictions generating showery and thunder activities mainly over elevated locations and highlands. Then a ridge of high-pressure system extends from the southeast and gradually strengthens and maintains northeasterly winds through the latter outlook period.
MARINE OUTLOOK:
A collection of marine observations from Aunu’u and King-Poloa wave buoys indicate wave and swell heights remain below the 2.5 metres advisory threshold. The global wave models suggest this particular trend of wave activities to persist throughout this outlook period, posing no threat for all coastal to marine waters of Samoa.
ADVISORIES/WARNINGS:
VALID: HEAVY RAIN ADVISORY
VALID: FLOOD ADVISORY
Weather On-Duty Team:
A. Liu, L. I. Tuatipi & F. U. Namulau’ulu.