TSSN, looks like thunderstorms of snow? :-hmmm http://www.flightplanning.navcanada.ca/Lat...ldwx_012-e.html Right down near the bottom by Toronto area.

Stratus,Sorry, can't find a TSSN combo on the weather depict you linked to but I suppose it is possible but rare (very unstable airmass, lake effect in winter?). I have on rare occasion seen thunderstorms in winter but they are usually associated with a warm frontal passage and a very unstable airmass.Kevin in CYOW

The GFA (Graphic Area Forecast) you were looking at was the 18Z Clouds and Weather.. here is the correct link: 18Z GFAAnd that is correct +TSSN And SN CLGS 0 AGL means Heavy Thunderstorm, snow, and 0 ceiling in snow... thats some nasty lake effect!!

Yeah, I live right near there. The visibility dropped from 15 to <1 in 5 minutes, and we started to get snow, not too light either, with gusts to 30 knots. Was very nasty indeed.