Althought I do not think it is 3 or 4 times the ratio (3dB is twice the power), as Bill suggested it is always a good idea if you can. What is happening does not surprise me since those 2 channels are the last ones on the UHF band (see the table on this forum) and therefore suffer the higher OTA propagation losses (well on any transmition line to be exact including the Air). On top of that, they also are less powered than CityTV digital and their TX antenna is located lower than the CityTV one to make matters even worst for you, and the rest of us, lol.

You were able to receive those far away stations that day (typically it happens in the summer months) due to abnormal or unusual highly favorable atmospheric conditions that allows radio signals to travel way way farther. A temperature gradient inversion makes the troposphera act as a duct (that is why the "radio" phenomena is called tropospheric duct) by reflecting the radio signals (or a portion of its spectrum , VHF/UHF in your case) on the higher layers of the troposfera back to earth. Heck there is someone in Ontario who received a TV signal from Havana, Cuba back in the 60's and also from England I beleive.

Very nice setup indeed and wait till the Aug 2011 digital conversion when this canadian stations are supposed to adjust their coverage area to match it somehow to their current analog version.