bibliophage, thanks for detailed and well-presented explanation of this phenomenon in your Staff Report found here: http://www.straightdope.com/mailbag/mlakeeffectsnow.html
I used to live in Toronto, and the second question/comment about the city I usually hear is, “Does it get a lot of snow like Buffalo?” Now, in addition to saying “no”, I can actually explain why not.
Question: did you research indicate whether the Niagara Escarpment has a noticeable effect on snowfalls around the southern edge of Lake Ontario (west of Niagara Falls, east of Hamilton/St Catherine’s)?
It’s hard to say about the Niagara Escarpment. I tried to find out what effect it would have, but I wasn’t certain enough of the answer to include it in the report. One rule of thumb I came across is that every 100’ of elevation above the lakes is good for an extra 7" of snow per year to the lee of the lakes. (That may be a good average, but the variation is considerable). The escarpment is maybe two or three hundred feet above Lake Ontario around there (I’m guessing), but to the windward of the Lake Ontario, so the effect would be less than if it were on the leeward side.
On the other hand, when the wind is off Lake Erie across the Niagara Peninsula, the air falls over the escarpment and warms and dries as it descends, which would tend to reduce the amount of lake-effect snow off Lake Erie for the northern part of the peninsula. Here’s a map showing snowfall averages around Lake Ontario and the eastern part of Lake Erie: http://tgsv5.nws.noaa.gov/er/buf/lakeffect/snowseason.html As you can see, the area just east of Hamilton has the least snow of any place on Lake Ontario. But it still gets more than the western part of Lake Erie around Toledo.
Interesting. That area east of Hamilton, where the snowfall is lowest on the map you linked, is also where the Escarpment comes the closest to Lake Ontario. You can see it here http://www.escarpment.org/About/overview.htm#map and here http://www.brucetrail.org/maps.htm . In the second map the NE is visible as the Bruce Trail along the ridgetop, in dark red.
On the other hand, if I understand your Staff Report correctly, the lower snowfall just east of Hamilton might have less to do with the Escarpment and more to do with the very short fetch (or complete lack thereof) across Lake Ontario which a west wind would typically have in that region.
The Escarpment does protect the wine-growing region north of it, inland from Lake Ontario, but by moderating the extremes of temperature, especially in the winter. But that’s not quite the same as its potential effect on snowfall.