FORECAST DISCUSSION

THURSDAY 15th APRIL 2021 (PM SHIFT)

TONIGHT & TOMORROW:

Few low-level clouds to the North of the islands, seen on the satellite imageries this evening. The current situation remains, as the West to Northwest wind-flow remains to prevail over the group in accord with the surface streamline analyses. Scatterometerpasses show light and variable winds near our area of responsibility as it is also an indication of the surface trough of low pressure situated just South of the group. The sounding profile also indicates gentle Northerly winds from the surface up the mid atmosphere. The absence of an upper-level system prohibits the development of convective activities. However, moisture availability near the surface as well as solar radiation as the main source of rain mechanism for today into tomorrow. Therefore, expect cloudy periods with some showers for tonight into tomorrow.

SATURDAY THROUGH THURSDAY:
A ridge of high pressure extending from a high-pressure system over the Tasman sea will ridge over the area by Thursday and will introduce the Tradewind regime across the island chain throughout the long term forecast. This’ll eventuate a wind change to the Southeasterlies by Saturday and may strengthen later in the outlook period. A weak upper-level trough has suggested by models to locate near our area by Sunday and will be a triggering mechanism for some showers at the starting of the new week. The global models predicted the CZ system to provide cloudy with moderate showery activities on Monday and Tuesday next week. Such as of the mentioned events may yet to be unfold for the following week a speed convergence may linger over the surface introducing showery content by mid-week of the new week.

MARINE OBSERVATION & OUTLOOK:

Current observations show wave heights ranging from 1.5-2 metres in height driven by gentle Easterlies and Southerlies as of this evening. Wave Watch models indicates wave heights to remain below the Advisory and Warning threshold for the foreseeable future. Therefore, marine outlook for the following week poses NO threat for all Samoa’s marine waters.

WARNINGS AND ADVISORIES:

NONE

DUTY FORECASTERS:

V. Wilson & Manu