FORECAST DISCUSSION
THURSDAY 7THMAY 2026 AM SHIFT
TODAY:
A dry upper airmass remains aloft as the surface Northwesterlies remain light for our area of forecast. However, TPW MIMIC imageries from the previous 9 hours signify values exceeding the 50mm threshold along with instability and sufficient lifting. A strong sheared environment persist at the mid-levels limiting duration of convective clouds for the nowcast period. Weather maps and latest ASCAT swaths during the early morning indicate a neutral area to the northwest as the trough of low pressure station along the SPCZ chain remains further south. Large dry slots are depicted at the mid-levels of the sounding profile which is acting as a hindering mechanism for sustained parcel entrainment from low to upper troposphere. Strong westerlies are forecasted to enter the upper atmosphere later tonight as the northwest flow dominates the surface to steering level. Global models and ensembles are predicting less showery activities for today, however, there is still a chance for a few thundery activities over mountainous regions of the main islands as the surface was widely expose to solar heating which may hit in the late afternoon into the evening.
SATURDAY THROUGH TUESDAY:
Based on the current global weather guidance, an intensified circulation within the SPCZ is expected to drift southward, dragging the major rainband, whereas a col area may linger over Samoa, with light and variable winds. Later on, the trade regime may dominate on Saturday throughout the outlook period, bringing showers along the mean wind flow and diurnal weather conditions. In this time frame, persisted strong west-to-southwesterly aloft, that generates dry airmass, hindered cloud formation to the surface, resulted in afternoon showers mainly over windward locations and elevated areas.
MARINE OUTLOOK:
The latest marine observations from Aunu’u and King Poloa wave buoys indicate that wave heights are fluctuating around 2.5 metres due to a southerly combined waves and swells . Global wave models suggest that these wave activities will gradually diminish later tonightacross Samoa’s marine waters, and expected to remain fluctuated 2-2.5 metres throughout the outlook period.
ADVISORIES/WARNINGS:
NONE
Weather Duty Team:
Gafa, Niko, Namulau’ulu & Tutasi