SYNOPTIC DISCUSSION
TUESDAY 4thNOVEMBER 2025 AM SHIFT
TODAY:
The trough of the low-pressure system that has caused unsettled weather conditions over Samoa for the past few days has gradually shifted further south. This has resulted in improved conditions observed across the islands this morning, leading to the deactivation of the Heavy Rain Advisory for the land areas of the country. Satellite channels have also confirmed the movement of the aforementioned system further southward, while all broad convection activities are occurring. Meanwhile, the northeasterly wind flow is prevailing in the area of responsibility this morning, as illustrated by ASCAT swaths, which align with the pressure charts from the Fiji Met-Service streamline analysis. However, the Pago Pago ascent sounding profile from this morning [12Z] indicated a slight instability with a moisture level of 54.50 mm PWAT, although more attention is directed towards the southern side of the group, which corresponds with the development of cumulus clouds observed over the highlands. The limitation on vertical storm development over the group this morning is attributed to the absence of an upper system, as upper divergence is more concentrated to the south, away from the forecast region. Additionally, it is expected to be partly cloudy with a few brief showers in some areas of the island group this afternoon.
WEDNESDAY THROUGH MONDAY:
In the proposed global model, it is anticipated that on Wednesday that on Wednesday where a trough of low pressure moving along the northeasterly wind flow that may located closely to the north, providing moist conditions and weak wind strength within the vertical profile of the atmosphere. A speed convergence will occur along the northeast flow, with expectations of this trend continuing into Thursday. This phenomenon will serve as a catalyst, increasing the likelihood of isolated showers throughout the island group, accompanied by varying short moderate rainfall. As we look towards the weekend, a change in wind patterns is expected, reinforcing the prevalence of the Easterlies, which are likely to persist into the following week. This alteration in wind direction will reintroduce minimal shower activity, signifying a subtle yet noticeable shift in weather patterns for the latter portion of the forecast period.
MARINE OUTLOOK:
Overall, all marine observations indicate levels significantly below the Advisory threshold, and forecasts suggest that wave activities will continue to stay well beneath the advisory/warning threshold for the duration of the outlook period.
ADVISORIES/WARNINGS:
CANCELLED: HEAVY RAIN ADVISORY
Weather Duty Team:
Gospel. Niko, Lao Ioane Tuatipi, Samuelu. Tavanā & Fuimaono Uili Namulau’ulu