SYNOPTIC DISCUSSION
MONDAY 27th JANUARY 2024 PM SHIFT.
TONIGHT:
A moist Northeasterly wind flow continues to influence Samoa’s weather bringing showery activities across the group at times. As per satellite data, a line of instability moves over the group and reside off the southern coast as of this evening leading to clearing skies and easing weather as observed. Such weather pattern is reflected from MIMIC TPW data where sufficient moisture is gradually moving south leaving the forecast zone. The sounding profile depicts moisture in the excess of 55 mm with a fairly dry profile through the upper level of the atmosphere. In addition, good instability lies over the group but without sufficient low-level moisture and lifting, thunderstorms are unlikely in the nowcast period in conjunction with the absence of upper divergence to support convective development and growth. Therefore, expect partly cloudy skies with some isolated showers and possible few thunderstorms that may develop elsewhere and move over the group.
TUESDAY THROUGH SUNDAY:
A surface to mid-level ridge of high-pressure is predicted to develop over Samoa by Tuesday resulting in mostly fine weather throughout the day, although afternoon thunderstorms are still possible over highlands. Showery activities will kick in early Wednesday as a trough of low pressure move over the group and is expected to reside southwest of Samoa by Thursday, allowing the northeasterly winds to prevail. A speed convergence along the northeasterlies is expected to bring episodes of showers across the group by Friday then easing into the weekend as the system pass eastward. In addition, a diffluence area may move over Samoa by Wednesday, aligning with the surface trough as mentioned, otherwise, a southerly aloft will prevail throughout the outlook period.
MARINE OUTLOOK:
The latest wave observations signify wave heights fluctuating below 2 meters over Samoa’s marine waters. The global wave models suggest these wave activities to persist below the advisory threshold of 2.5 metres throughout the outlook period.
ADVISORIES/WARNINGS:
NONE
Weather Duty Team:
F. Kalapani, G. Niko & S. Taupa’ū.