SYNOPTIC DISCUSSION
THURSDAY 16th OCTOBER 2025 AM SHIFT
REST OF TODAY:
The weather for the island group has been characterised by a persistent easterly flow, underpinned by a subtropical anticyclone located to the southeast of Samoa. This synoptic setup has promoted widespread atmospheric stability. As a result, significant rainfall is expected to be confined to that generated by orographic uplift, low-level convergence within the flow, and diurnal surface heating effects.
FRIDAY THROUGH TUESDAY:
Global weather models suggest that the convergence zone is expected to approach the forecast area from the north by late Friday, with the possibility of descending over the islands by Saturday. This system is likely to bring heavy rainfall along with gusty periods by the end of this week. The eastward movement of the anticipated high-pressure system, located to the northeast of Australia, is expected to strengthen the previously mentioned convergence zone from Sunday into Monday. This will lead to the continuation of unstable weather conditions in our area of concern. Furthermore, an upper diffluence is anticipated to form north of the islands by Saturday, which may enhance the downstream northwesterly flow aloft, potentially boosting the previously mentioned surface system. A slightly improved conditions are expected at the end of this outlook period due to the likely persistence of the easterly trade winds.
MARINE OUTLOOK:
The marine observational data shows that wave and swell heights fluctuate below 2.5 meters, and this trend is expected to continue throughout the week and possibly into the following week. Therefore, it poses no significant threats to the coastal and marine waters of the country.
ADVISORIES/WARNINGS:
NONE
Weather Duty Team:
MJS, Punipuao Huch & Fuimaono Uili Namulau’ulu.