SYNOPTIC DISCUSSION
SUNDAY 30th NOVEMBER 2025 AM SHIFT
TODAY INTO TONIGHT:
The satellite imagery of the disorganized SPCZ engulf the area of responsibility. Where, it embedded within a trough of low pressure system , as it was closely monitor from the large scale scatterometer swaths and the relative vorticity field at the 850 level revealing a weak negative cyclonic signature an implication of surface lifting. Present high moisture content and moderate instability within the atmosphere, along with persisted upper divergence aloft, that resulted to scattered showers with periods of brief heavy downpours and a few thunderstorms today. Thus, it maintain risk of flooding at rivers and low-lying areas. Thence, the highlighted warning and advisory remains in effect for all land areas of Samoa.
Tonight, considering the area to be unstable, the model consensus suggested that the system may still linger over the Samoa Island with the present upper-level system for enhancement.
MONDAY THROUGH FRIDAY:
Majority of models are hinting the arrival of the upper system forecasted over the past few days to drift eastward late Sunday through Monday. This system is expected to enhance cloud growth for the start of the new week as the surface system fluctuates along our island chain. Winds at the steering level will be predominantly from the Westerly direction and weak sheared environment will be an additional feature possibly contributing to the uplifting of air within the mid atmosphere. A reduction in rainfall accumulation within 24-hours is forecasted for the mid to latter days of this outlook period. The continuation of the current valid SWI products particularly for land may be cancelled on Tuesday if model updates are hinting the same trend for the upcoming days.
MARINE OUTLOOK:
As of now, the recent marine observational data generally revealed that Samoa’s marine and coastal waters composed of wave and swell heights fluctuate below 2.5 metres. However, the wave models suggested a long-period elevated northerly swell originate from the north is expected to enter our country’s marine areas early tomorrow, with a low-to-moderate chance of impact late tomorrow and continue to Tuesday with a wave period of more than 18s. Hence, the Marine Advisory remains valid for all marine areas.
ADVISORIES/WARNINGS:
VALID: HEAVY RAIN WARNING
VALID: FLOOD ADVISORY
VALID: MARINE ADVISORY - ALL OF SAMOA
Weather Duty Team:
A. Liu, L. I. Tuatipi, S. Maualaivao & C. Baker.