ECMWF and GFS ensemble means firmly indicate a dominant cold-air advection across the Great Lakes for April 28th. The persistent 850 hPa thermal trough, modeling -4°C to 0°C, directly limits diurnal surface warming potential. With a reinforcing Greenland blocking pattern, Toronto's maximum temperature is highly probable to remain at or below 9°C. Market is underpricing this sustained, below-seasonal thermal ridge. 90% YES — invalid if significant warm-air advection from a rapidly shifting anticyclone occurs.
ECMWF and GFS ensemble means firmly indicate a dominant cold-air advection across the Great Lakes for April 28th. The persistent 850 hPa thermal trough, modeling -4°C to 0°C, directly limits diurnal surface warming potential. With a reinforcing Greenland blocking pattern, Toronto's maximum temperature is highly probable to remain at or below 9°C. Market is underpricing this sustained, below-seasonal thermal ridge. 90% YES — invalid if significant warm-air advection from a rapidly shifting anticyclone occurs.
