SYNOPTIC DISCUSSION
FRIDAY 27th MARCH 2026 AM SHIFT
TODAY:
Single cell convective clouds were observed over satellite animation throughout this morning within the vicinity of the group. Although brief heavy falls mainly experienced over elevated areas of both main islands yesterday evening, majority of the deep convections were concentrated over the marine waters of Samoa early this morning. Vorticity signature are portraying favorable conditions at the low to mid level atmosphere where the trough of low pressure is stationed. TPW snapshots along with figures from the latest sounding profile indicates sufficient and increased atmospheric column moisture present compared to the past day. Veering winds tend to imply the presence of warm air advection between the surface and 600mb level where moisture is available. The axis of the upper trough remains just north of the island chain which is contributing to some of the active convections along the surface to mid-level synoptic rain-maker system. Model consensus suggest unsettled weather for the now-cast period similarly to yesterday, however, sky cover throughout the day may increase in southern areas. Thus, anticipate cloudy spells with isolated showers, brief heavy falls in some areas and thunderstorms likely for today.
SATURDAY THROUGH WEDNESDAY:
The abovementioned upper system will fluctuate over the area of forecast through the start of the new week. A probable low-level circulation is forecasted to develop west of Savaii allowing a northwesterly wind flow to persist at the lower atmosphere for the first half of this outlook period. Thus, strong wind gradient will introduce 15-20 knots northerly winds through mid-week next week maintaining unstable and moist weather for the weekend. The update from the severe weather guidance are marking our area as being moderately likely to be impacted by 100-150mm of precipitation within 24 hour period for tomorrow into Monday. The SPCZ will establish over the island chain through the latter days, hence, the existence of equatorial moisture will contribute to deteriorating weather forecasted for the upcoming week.
MARINE OUTLOOK:
Generally, the observed marine data indicate that the wave and swell heights across Samoa’s marine waters are still below the 2.5 metres threshold value, which poses no threat. Wave models suggest this trend is expected to persist throughout the forecast period.
ADVISORIES/WARNINGS:
VALID: HEAVY RAIN ADVISORY
Weather Duty Team:
Gafa, Sofeni, Uili & Tavana.