SYNOPTIC DISCUSSION
WEDNESDAY 30th APRIL 2025 AM SHIFT.
TODAY INTO TONIGHT:
The predominant intensifying 1029 hPa area of high-pressure system is positioned further south of the Southern Cooks, now directing easterly winds. A decreasing amount of cloud coverage correlates to the insufficiency of moisture content within the atmosphere, but it is a suitable weather state for surface heating. On top of that, the orographic lifting at windward locations and elevated terrains could lead to stratiform clouds. Even so, the presence of a strong wind shear environment across the island chain, with mid-to-upper level dry airmass, suppresses cloud formation. Henceforth, the atmosphere is stable, implying fair weather conditions. On the other hand, a weak convergence zone in conjunction with a trough of low-pressure system, which is signified by convective clouds with associated accumulated rainfall activities. There is a low-to-moderate chance for some showery activities tonight, because of the mean wind flow. What's more, an upper trough of low-pressure system from the east will slowly move over the country later tonight.
THURSDAY THROUGH TUESDAY:
Generally, the model consensus predicted minimal showery activities except on Friday. In that time frame, the easterly wind flow with some brief showers. Meanwhile, an upper trough of low-pressure system is likely to sit over Samoa on Thursday while slanting westward but propagating eastward, which introduces the southeasterly aloft across the island chain on Friday through Monday. There is a likelihood that this upper system evolves into an upper-level circulation likely to be situated closely north of the area of concern in the later part of the outlook period. From Friday to Monday, winds are expected to veer southeast with possibilities of becoming light-to-moderate wind speed. The previously stated convergence zone is interconnected with a trough of low-pressure system that may migrate over the country on late Monday into Tuesday.
MARINE OUTLOOK:
A collection of marine observations justifies that wave activities remain below the 2.5 meters below Advisory level threshold mark. The Wave Watch model suggests the present wave conditions are highly likely to persist through until Tuesday in the new week. Where there is a low probability, another episode of southern swells is generated by another predicted area of high-pressure system located across New Zealand.
ADVISORIES/WARNINGS:
NONE
Weather On-Duty Team:
A. Liu, A. Niko & N. Tutasi.