Markham, ON - Yet another clipper is in shape for Southern Ontarians. This clipper will take place across most of Ontario starting from Tuesday late morning ending Wednesday at dawn. I have run the clipper forecast through WXSIM (Atmospheric Simulator), and here's the summary for Tuesday, Tuesday Night, and Wednesday:

Tuesday: Mostly cloudy in the morning, becoming dense overcast in the afternoon.     A chance of a mix of snow and sleet in the afternoon. High 2. Wind south around     16 kph, gusting to 28 kph, in the morning, becoming 28 kph in the afternoon. Chance of precipitation 50 percent. Precipitation (liquid equivalent) mostly around 2 mm. Snow or ice (on ground) accumulation about a cm.

Tuesday night: Dense overcast in the evening, becoming cloudy after midnight.        Snow likely in the evening, then a chance of snow after midnight. Low -7. Wind chill down to -13. Wind south around 25 kph in the evening, becoming west after midnight. Chance of precipitation 70 percent. Precipitation (liquid equivalent) mostly around 10 mm. Snow accumulation 6 to 10 cm.                  

Wednesday: Cloudy in the morning, becoming mostly cloudy to cloudy in the afternoon. A chance of snow. High -6, but temperatures falling in the afternoon.  Wind northwest around 24 kph. Chance of precipitation 40 percent. Precipitation (liquid equivalent) mostly less than 2 mm. Snow accumulation about a cm.   

The forecast was strictly based on the available retrieved from the 06 Z GFS. According to this version of the GFS, it shows that precipitation will start across much of Southern Ontario around noon hours. However, personally, I think the snow can start before noon hours, as scattered flurries, and probably will not accumulate.

In the program WXSIM, it is suggesting a centimeter of snow will fall in the morning hours, then a brief pause of overcast periods, when temperature soars up to 2 C, as we enter the warmer sector of the clipper. During the evening hours, when the cold front moves through Ontario, stronger bands of snow will move through. Across Southern Ontario, light snow will fall. According to the GFS, it seems like the Golden Horseshoe may see 1 or 2 hours moderate snow, falling at intensity near 0.5 cm to 1 cm / hour. By the time the system moves out, a possible 10 cm of snow will accumulate, which brings us closer to the record (we need 14 more cm of snow to break the record).

My personal insights, however, is that majority of the 10 cm snow will fall as wet snow, meaning not much of the snow will accumulate. I am thinking more like 3 to 8 cm across the Greater Toronto Area, while significantly more across Southern Muskoka, Northern Simcoe, and parts of Parry Sound. Those areas can see upwards to 15 cm.