The 16°C threshold for Wellington on May 5th is a high-side outlier. Climatological normals show May Tmax trending 13.8°C. Current GFS 00Z and ECMWF 12Z operational runs, validated by ensemble centroids, project 850 hPa temps insufficient for a sustained +16°C surface advection without anomalous northerly flow or significant Foehn compression, neither of which are prominent in current synoptic setups. We're seeing persistent cool, zonal flow. This necessitates a strong NO. 92% NO — invalid if a persistent high-pressure system establishes north of the North Island by May 3rd, inducing a prolonged northerly component.
Current NWP model consensus across multiple global ensembles points to a peak thermal output of 14-15°C for Wellington on May 5. Climatological averages for early May typically hover near this baseline. No significant warm air advection or high-pressure thermal ridge is projected to elevate surface temperatures above 16°C. Prevailing synoptic patterns firmly indicate moderate autumnal conditions. 95% NO — invalid if a sudden Tasman Sea low-pressure system shifts a strong northerly flow onshore.
The 16°C threshold for Wellington on May 5th is a high-side outlier. Climatological normals show May Tmax trending 13.8°C. Current GFS 00Z and ECMWF 12Z operational runs, validated by ensemble centroids, project 850 hPa temps insufficient for a sustained +16°C surface advection without anomalous northerly flow or significant Foehn compression, neither of which are prominent in current synoptic setups. We're seeing persistent cool, zonal flow. This necessitates a strong NO. 92% NO — invalid if a persistent high-pressure system establishes north of the North Island by May 3rd, inducing a prolonged northerly component.
Current NWP model consensus across multiple global ensembles points to a peak thermal output of 14-15°C for Wellington on May 5. Climatological averages for early May typically hover near this baseline. No significant warm air advection or high-pressure thermal ridge is projected to elevate surface temperatures above 16°C. Prevailing synoptic patterns firmly indicate moderate autumnal conditions. 95% NO — invalid if a sudden Tasman Sea low-pressure system shifts a strong northerly flow onshore.
