FORECAST DISCUSSION

MONDAY 19th OCTOBER 2020 (AM SHIFT)

TODAY AND TONIGHT:

A light and moist Northwest wind flow prevails over Samoa. Meanwhile, a trough of low pressure with associated cloud and showers lies West. This system lies under a weak upper divergence which enhanced its development in the past 12 hours. However, high shear environment alongside the system with the support of an inversion near 750mb may suppress vertical development of clouds within our area of responsibility. Additionally, global models predicted the trough to sink southeast as the low pressure system to the south of Niue moves. Therefore, anticipate cloudy conditions at times with some showers and few thunderstorms possible, mainly over highlands due to surface heating and orographic lifting. Clearing after sunset.

TUESDAY THROUGH SUNDAY

A high pressure system further southwest to the North of New Zealand ridging over the forecast zone will introduce Tradewind flow with stable weather conditions by tomorrow. However, a speed convergence is likely along the ridge due to wind strength differences. This will provide isolated showers within mid-week. Another trough of low pressure currently located further East is forecast to descend over the group by Friday with rainfall activities towards the weekend. Will monitor the movement of this system and update accordingly when future model runs are available.

MARINE OBSERVATION & OUTLOOK 
Current observations from the Aunu’u buoy and altimeter indicated wave activities below the advisory threshold and expected to remain so for the rest of the outlook period.

WARNINGS AND ADVISORIES

NONE

DUTY FORECASTERS:

E. Toluono