SYNOPTIC DISCUSSION
SUNDAY 01st JUNE 2025 AM SHIFT
TODAY:
Mean sea level pressure [MSLP] readings over the past 12 hours maintained between 1013mb and 1014mb with reference to the METAR observations. Such is evident of the intensified ridging extending from the high-pressure centred west of New Zealand. Tree branches moving indicative of the dominant moderate Easterlies taking over the surface and low level troposphere. Cloudy spells were also observed streaming along the wind flow with less potential of long lived convections confirmed over the CIMMS analysis. The absence of upper divergence and low-level convergence marked over the islands limits the chance of sustained parcel(s) ascent within the nowcast period. Thus, models predictions for the nowcast period are hinting partly cloudy skies with brief showers as the Easterly [tradewind regime] becomes the major weather driver.
MONDAY THROUGH FRIDAY:
A slight increase in precipitation is predicted to make land fall tomorrow in the afternoon and such will be due to an episode of speed convergence associated with the Easterly moderate flow. A chance of a few thunderstorms is anticipated within this short time period but model traces from ECMWF suggest the moisture focused at the surface to the top layer of the low-level atmosphere. Later on through mid-week, as the high-pressure situated further southwest maintains its eastward progression, a probable trough will descend from the northeast. Such may provide isolated to scattered showers by Wednesday into Thursday, as for Friday, moist northeast will dominate the surface with fine weather conditions likely over our forecast zone.
MARINE OUTLOOK:
Observations of swell and wave heights across our marine waters continue to fluctuate below 2.5 metres. Meanwhile, the intensified high-pressure system located west of New Zealand is forecasted to slowly migrate eastward through Wednesday. The movement of this system will likely elevate wave heights above 2.5 metres this afternoon. As for Tuesday into Wednesday, easterly winds of 35 – 40 km/h will affect our marine waters and will maintain these severe weather conditions over Samoa’s southern seas.
ADVISORIES/WARNINGS:
VALID: MARINE ADVISORY – SOUTHERN MARINE WATERS
Weather On-Duty Team:
Gafa, Niko & Huch.