FORECAST DISCUSSION

THURSDAY 19th MAY 2022 – AM SHIFT

TODAY:

The latest streamline analysis compared with the latest satellite imageries indicates the movement of a squall line from the east which aligns with a mid-level trough of low pressure. This system is driven by the easterlies advancing with cloud content towards the northern areas of the group. The squall line is expected to provide increased cloud content with moisture abundance as well as remnants of the surface convergence zone which lingers in the southern vicinity of Samoa. Although improved weather conditions were experienced in the morning, the movement of the squall line inhibits instability, thus prolonging such activities to remain over the country. For tonight, expect these activities to relocate further west from the islands whilst the convergence zone to the south may continue to liner into tomorrow with associated activities reducing as winds start decreasing.

FRIDAY THROUGH WEDNESDAY:

The abovementioned systems are anticipated to advance westward by Friday as the ridge extends from a high-pressure system situated south towards the Islands. However, a warm Northeast wind flow may keep moisture over the AOR. Such weather patterns could cause moderate downpours mainly at noon over elevated areas. A dominant high-pressure system on the steering level will keep the easterlies to persist throughout the outlook period. Easterlies will continue for the remainder of the outlook period hence improved weather conditions are expected with some passing showers.

Tropical Disturbance 11F (TD11F) was named TC GINA Cat 1 in the early hours of today, although this system continues to project southwest near the vicinity of Vanuatu it poses no threat to Samoa. Moreover, the system lies under a moderate upper-level divergence with its eye in a moderate shear environment.

MARINE OUTLOOK:

Recently, observations indicate an improving trend in wave activity and ranges from 1.5-2 metres. An area of moderate to fresh southeast winds now lies further south from the group hence the improving wave activities. Therefore, the previously enforced Marine Advisory which remained active for Southern Marine waters is now CANCELLED. However, a new wave surge is to enter the forecast zone on Monday of the new week, therefore, a likely issuance of severe weather information for marine areas prior to the system’s arrival.

WARNING/ADVISORY:

HEAVY RAIN ADVISORY.

MARINE ADVISORY FOR SOUTHERN WATERS OF SAMOA - CANCELLED

TEAM PM-SHIFT:

S Gafa & MJS