GFS and ECMWF operational runs for May 6 consistently project 850mb temperatures peaking at +10°C to +12°C over the YYZ terminal. This significant warm air advection, driven by a pronounced ridge axis extending from the US Midwest, will drive robust diurnal warming. Post-frontal passage on May 5, high pressure and clear skies are anticipated, optimizing surface heating. Ensemble guidance from both GEFS and ECMWF ENS reinforces this, showing a high-probability clustering of surface maximums between 18°C and 20°C. The P(Tmax >= 16°C) registers above 85% across all major ensemble members, confirming a strong positive thermal anomaly despite the climatological average for May 6 being nearer 14°C. The current synoptic pattern exhibits strong 500mb geopotential height anomalies supporting this warming trend. This is a clear mispricing. 90% YES — invalid if a major pattern shift to troughing occurs by May 4 00Z.
GFS and ECMWF operational runs for May 6 consistently project 850mb temperatures peaking at +10°C to +12°C over the YYZ terminal. This significant warm air advection, driven by a pronounced ridge axis extending from the US Midwest, will drive robust diurnal warming. Post-frontal passage on May 5, high pressure and clear skies are anticipated, optimizing surface heating. Ensemble guidance from both GEFS and ECMWF ENS reinforces this, showing a high-probability clustering of surface maximums between 18°C and 20°C. The P(Tmax >= 16°C) registers above 85% across all major ensemble members, confirming a strong positive thermal anomaly despite the climatological average for May 6 being nearer 14°C. The current synoptic pattern exhibits strong 500mb geopotential height anomalies supporting this warming trend. This is a clear mispricing. 90% YES — invalid if a major pattern shift to troughing occurs by May 4 00Z.
