Aggressive model convergence indicates a high temperature breach above the 11°C threshold. The ECMWF HRES D+3 run pegs the Toronto high at 12°C, while the GFS 12z run D+3 projects 13-14°C. The GEPS/EPS ensemble mean consistently positions the daily max at 12.5°C, with a tight 70% confidence interval centered distinctly above 11°C. While persistent low-level stratus and a cool easterly advection from Lake Ontario, influenced by a lingering weak trough, will suppress full diurnal warming, the 850mb temperature anomaly is not severe enough to lock the surface high at or below 11°C. Boundary layer dynamics, even with reduced solar insolation, will allow for a modest push past this level. Sentiment: Local Canadian forecasting agencies have already adjusted their May 6 highs to 12-13°C based on these updated model runs. 90% NO — invalid if official reporting station data indicates significant unexpected cold air damming.
Aggressive model convergence indicates a high temperature breach above the 11°C threshold. The ECMWF HRES D+3 run pegs the Toronto high at 12°C, while the GFS 12z run D+3 projects 13-14°C. The GEPS/EPS ensemble mean consistently positions the daily max at 12.5°C, with a tight 70% confidence interval centered distinctly above 11°C. While persistent low-level stratus and a cool easterly advection from Lake Ontario, influenced by a lingering weak trough, will suppress full diurnal warming, the 850mb temperature anomaly is not severe enough to lock the surface high at or below 11°C. Boundary layer dynamics, even with reduced solar insolation, will allow for a modest push past this level. Sentiment: Local Canadian forecasting agencies have already adjusted their May 6 highs to 12-13°C based on these updated model runs. 90% NO — invalid if official reporting station data indicates significant unexpected cold air damming.
