SYNOPTIC DISCUSSION
FRIDAY 13th JUNE 2025 PM SHIFT
TONIGHT INTO TOMORROW:
An intensifying area of high pressure system located south of the Southern Cooks continuously maintains the moderate southeasterlies across the island chain. Samoa generally experience cool and dry atmospheric conditions, as both the integrated water vapour animation and sounding profile delineate a stable weather state. Furthermore, the vertical profile of the atmosphere still shows a present inversion layer, which hinders convection across the island. In addition, as support for the surface system, an area of high pressure still lingers over the area of responsibility.
Tomorrow, the model consensus generally suggests a moderate-to-high chance that the mean wind flow is expected to persist. A good correlation between the surface and upper systems. Thus, expect cool and dry weather patterns.
SATURDAY THROUGH THURSDAY:
The global weather models indicate predominantly pleasant weather across Samoa until at least Monday of the upcoming week, except typical orographic showers occurring in the highlands during the afternoon. The likelihood of thunderstorms remains low throughout this week, as moderate southeasterly winds are expected to continue, driven by high-pressure systems that prevail at atmospheric levels, resulting in dry and suppressive conditions. To clarify, moderate to fresh east to southeasterly winds are maintained at mid levels, while southerly winds are more prevalent at upper levels. Furthermore, the winds from the surface to mid levels are anticipated to become light to gentle in strength by the new week, as a weak surface trough of low pressure begins to form from the northeast of the group. This low-pressure trough is projected to make landfall by Tuesday, potentially bringing light to moderate showers across the group. The previously mentioned surface showery activities are likely to persist through Wednesday, with light intensity expected. This is attributed to another high-pressure system that may extend ridges over our area of responsibility from the eastern side of the Fijian group, which may direct southeasterly winds to be dominant on the conclusion of the outlook period. The predominance of high-pressure systems at mid-to-upper levels over Samoa may inhibit significant convective storm growth and the development of the weather system.
MARINE OUTLOOK:
The most recent marine observations signify wave and swell heights remain below 2.5 metres across the islands’ marine waters, which poses no significant threat to our marine areas. There is a possibility, these wave activities will proceed throughout the outlook period.
ADVISORIES/WARNINGS:
NONE
Weather On-Duty Team:
M.J.S, A. Liu, S. Tavanā & L. I. Tuatipi.