SYNOPTIC DISCUSSION
WEDNESDAY 01st APRIL 2026 AM SHIFT
REST OF TODAY:
The deterioration in weather conditions persists across the group, driven by the SPCZ, which remains stationary over the islands associated with embedded low-pressure systems. Although breaks in rainfall activity are anticipated, the onset of widespread rain with periods of heavy rainfall, gusty winds, and thunderstorms remains likely. From the lower to the mid atmosphere, a deepening low-level circulation remains stationary, according to satellite analysis from earlier this morning. Moisture content associated with the system remains abundant across the group; prolonged periods of rain also increase the risk of flooding for rivers, ford crossings, and low-lying areas. Therefore, the Heavy Rain Warning and Flood Warning remain in place for all land areas of Samoa, and the general public is cautioned to remain vigilant. However, the strengthening of the ridge of high pressure from the east tends to usher a moist northerly over the islands, which repositions the SPCZ slightly south of Samoa, whilst its cold tops shear over our southernmost shores, prolonging brief showery conditions. Anticipate a gradual decline of convective showers from later this evening.
THURSDAY THROUGH MONDAY:
Principally, the model consensus suggested that the severe weather system would shift further southwest, as a ridge of high pressure to the southeast slowly strengthens on Thursday, which would sustain possible moderate-to-fresh northerly wind flow with gustiness. Then, the mean wind flow gradually becomes easterly on Friday as the previously stated ridge of high pressure moves westward, hinting that the trade wind regime will become the dominant weather feature across the forecast area in the latter part of the outlook period. In addition, a weak upper trough may influence the group through at least Wednesday, 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:
Currently, the marine observations from King Poloa and Aunu’u, as well as altimeter data, continue to reveal that the wave and swell heights fluctuated around 2 metres, which suggests no imminent threat across Samoa’s marine waters. Global wave models suggest that this wave activity will remain below the advisory threshold of 2.5 metres throughout this outlook period.
ADVISORIES/WARNINGS:
VALID: HEAVY RAIN WARNING
VALID: FLOOD WARNING
Weather Duty Team:
MJS, Albert Niko, Aquinas Uili & Christopher Baker.