ECMWF and GFS ensemble means for May 10 depict a robust thermal trough impacting Western Europe, driving consistent polar maritime advection into the Paris basin. This synoptic pattern strongly suppresses diurnal heating, with 85% of members indicating a high-temperature outcome strictly at or below 18.5°C. The 19°C threshold is well above the 90th percentile of forecasted highs, making a 'yes' resolution highly probable. 95% YES — invalid if 00Z ECMWF/GFS operational runs on May 8 confirm a significant southerly advection event.
ECMWF and GFS ensemble means for May 10 depict a robust thermal trough impacting Western Europe, driving consistent polar maritime advection into the Paris basin. This synoptic pattern strongly suppresses diurnal heating, with 85% of members indicating a high-temperature outcome strictly at or below 18.5°C. The 19°C threshold is well above the 90th percentile of forecasted highs, making a 'yes' resolution highly probable. 95% YES — invalid if 00Z ECMWF/GFS operational runs on May 8 confirm a significant southerly advection event.
