SYNOPTIC DISCUSSION
MONDAY 03rd MARCH 2025 PM SHIFT.
TONIGHT:
Active rain bands associated with a speed convergence along the northwest wind flow prevails over Samoa. Such was able to maintain moist and unstable weather conditions for the late evening and was verified over the most recent weather maps. The ASCAT observations confirmed the axis of the ridge extending to the north of the island chain with broad areas of convections popping up along the major convergence zone chain. The upper divergence and low wind shear persists aloft which contribute to the development of numerous convective activities visible over the IR and Water vapor channels of the Himawari Satellite. Models are in good agreement of the amount of precipitation and coverage for tonight with a higher likelihood of thunderstorms and brief moderate falls in some parts of the country.
TUESDAY THROUGH SUNDAY:
Global weather models suggest an intensifying precipitation by early Tuesday continuing throughout the day due to the abovementioned speed convergence jointly with the SPCZ residing just south of Samoa. An upper trough is forecast to build from the south and provide upper divergence on Tuesday through Wednesday that will likely enhance convective storms. MOGREPS-G depict a 20-40% chance of these activities to exceed 25mm in 12 hours where 40-60% probability lies just south of the group. Therefore, periods of heavy rainfall are likely on early Tuesday and throughout the day. Showery activities may continue through Wednesday as the SPCZ lies just south of the group and then easing by Thursday through Friday as the convective system recedes southward. The SPCZ is forecast to approach the islands by Saturday with associated moisture and instability.
MARINE OUTLOOK:
The latest marine observations indicate wave heights fluctuating within the range of 1 – 2 metres over all marine waters of Samoa. Global wave models suggest these wave activities to persist below the advisory threshold of 2.5 metres throughout this outlook period.
ADVISORIES/WARNINGS:
VALID: HEAVY RAIN ADVISORY
Weather Duty Team:
Gafa, Niko & Maualaivao