The synoptic pattern for May 7 explicitly signals a robust positive temperature anomaly for Wellington. ECMWF 12z and GFS 00z operational runs decisively project an amplified Tasman ridge inducing strong northerly advection across the lower North Island. 850mb temperatures are modelled at +11.5°C, a 4°C anomaly, with significant adiabatic warming potential from a pronounced foehn effect off the Tararua Ranges. The ECMWF ensemble median for Wellington's maximum temperature is 17.1°C, with a striking 78% of members printing >=16°C. GFS ensemble output corroborates this, showing 69% probability. Current Tasman Sea SSTs are +1.4°C above climatological norms, providing a pre-warmed airmass source. This is a high-confidence trade on established warm advection dynamics. 95% YES — invalid if the Tasman ridge axis shifts east, prompting early southerly onset.
The synoptic pattern for May 7 explicitly signals a robust positive temperature anomaly for Wellington. ECMWF 12z and GFS 00z operational runs decisively project an amplified Tasman ridge inducing strong northerly advection across the lower North Island. 850mb temperatures are modelled at +11.5°C, a 4°C anomaly, with significant adiabatic warming potential from a pronounced foehn effect off the Tararua Ranges. The ECMWF ensemble median for Wellington's maximum temperature is 17.1°C, with a striking 78% of members printing >=16°C. GFS ensemble output corroborates this, showing 69% probability. Current Tasman Sea SSTs are +1.4°C above climatological norms, providing a pre-warmed airmass source. This is a high-confidence trade on established warm advection dynamics. 95% YES — invalid if the Tasman ridge axis shifts east, prompting early southerly onset.
