SYNOPTIC DISCUSSION
WEDNESDAY 04th OCTOBER 2023 – PM SHIFT
TONIGHT INTO FRIDAY:
The high-pressure centred south of Southern Cooks continues to relax whilst migrating eastward. Meanwhile, a trough of low pressure stationed northwest with active rain bands and fresh to strong southeast surge impacted the area today. ASCAT winds observations signify weakening Easterlies currently impacting the forecast zone. These synoptic systems will maintain their position outside our vicinity as another high-pressure system stationed north of New Zealand ridges over the islands. However, the major system expected to provide a slight inducement in showery activities is located northeast of the area. This system is predicted to landfall tomorrow in the afternoon and may generate brief heavy downpours until early Friday. A strong westerly wind flow riding along the jet stream will migrate overhead and may enhance activities near the surface. Henceforth, a heavy rain advisory is now enforced due to such variability in precipitation pattern.
SATURDAY THROUGH TUESDAY:
The high-pressure system centred near New Zealand will introduce drier weather conditions with cool and moderate southeast winds to persist through Sunday. The developing subsidence area at the mid-upper level within this period will resist clod development and therefore support drier conditions to persist. A weak trough will overhead the island chain by Monday and will likely promote some showery activities at the latter part of the outlook period. However, the aforementioned subsidence area will persist throughout the long-term forecast and may thus suppress cloud development at the latter part of the forecast period. Moderate southeast winds are predicted to dominate the long-term forecast.
MARINE OUTLOOK:
The high-pressure system remains to the South of Southern Cooks and continues to relax as it migrates eastward. Fresh East to Southeast wind relocates West whereas rough seas continue to affect our marine waters. Observations of wave heights this afternoon indicate a decreasing trend compared to the morning. These severe weather conditions are predicted to reside Southwest of Samoa by tomorrow. Hence, such warrants the cancellation of the Wind Advisory and downgrading of the Marine Warning into a Marine Advisory.
ADVISORY/WARNING:
VALID: MARINE ADVISORY
VALID: HEAVY RAIN ADVISORY
CANCELLED: MARINE WARNING
CANCELLED: WIND ADVISORY FOR SOUTHERN SIDE & HIGHLANDS
WEATHER ON DUTY TEAM:
Gafa, Aroni & Tuatipi