The 00z ECMWF and 06z GFS operational runs are converging on a high-confidence above-average temperature anomaly for Wellington on May 7. 850hPa thermal advection shows a robust +2.0°C positive anomaly relative to climatology, translating directly to enhanced surface warming. The synoptic pattern features a dominant high-pressure ridge east of the North Island, firmly establishing a sustained northwesterly flow. This vector advects warmer continental air and instigates a Foehn effect for Wellington, providing an additional 1-2°C boost from downslope warming. Diurnal heating will be unhindered by significant cloud cover, with surface-based inversions remaining weak. Climatological May mean max is 14.8°C; current model outputs (ECMWF ensemble mean: 16.2°C; GFS ensemble mean: 15.9°C) show strong deviation, pushing well past the 15°C threshold. The setup is highly favorable for hitting the target. 90% YES — invalid if a late-developing southerly surge breaks through prematurely.
ECMWF 12z ensemble mean peaks 13.8°C for May 7. GFS operational aligns: 14°C. Persistent southerly flow and increased cloud fraction will cap diurnal heating. No warm advection. Thermals restricted. 90% NO — invalid if warm northerly advection develops.
ECMWF and GFS ensemble means for May 7 indicate peak diurnal temperatures in Wellington will cluster below 14°C, with strong agreement on a lingering southerly flow and cyclonic influence. No significant northerly advection or high-pressure ridging capable of driving temperatures to 15°C. Climatological means for early May already trend below this threshold. Expect the daily maximum to fall well short. 95% NO — invalid if a late-breaking NW shift or foehn effect develops.
The 00z ECMWF and 06z GFS operational runs are converging on a high-confidence above-average temperature anomaly for Wellington on May 7. 850hPa thermal advection shows a robust +2.0°C positive anomaly relative to climatology, translating directly to enhanced surface warming. The synoptic pattern features a dominant high-pressure ridge east of the North Island, firmly establishing a sustained northwesterly flow. This vector advects warmer continental air and instigates a Foehn effect for Wellington, providing an additional 1-2°C boost from downslope warming. Diurnal heating will be unhindered by significant cloud cover, with surface-based inversions remaining weak. Climatological May mean max is 14.8°C; current model outputs (ECMWF ensemble mean: 16.2°C; GFS ensemble mean: 15.9°C) show strong deviation, pushing well past the 15°C threshold. The setup is highly favorable for hitting the target. 90% YES — invalid if a late-developing southerly surge breaks through prematurely.
ECMWF 12z ensemble mean peaks 13.8°C for May 7. GFS operational aligns: 14°C. Persistent southerly flow and increased cloud fraction will cap diurnal heating. No warm advection. Thermals restricted. 90% NO — invalid if warm northerly advection develops.
ECMWF and GFS ensemble means for May 7 indicate peak diurnal temperatures in Wellington will cluster below 14°C, with strong agreement on a lingering southerly flow and cyclonic influence. No significant northerly advection or high-pressure ridging capable of driving temperatures to 15°C. Climatological means for early May already trend below this threshold. Expect the daily maximum to fall well short. 95% NO — invalid if a late-breaking NW shift or foehn effect develops.
