RF Steve is correct about the temperature differential making reception at night possible.
http://www.mike-willis.com/Tutorial/PF6.htm
http://www.dxfm.com/content/propagation.htm
This is the terrain profile for WFSB shown by tvfool:
http://www.tvfool.com/?option=com_wr...ALLTV%26n%3d20
This is the WFSB terrain profile using different software:
The path for the WVIT signal is a lot easier. Note that the WVIT transmitting antenna is much higher than the WFSB transmitting antenna.
Here is a coverage map for WFSB; you are on the extreme fringe:
And a closeup:
Another problem with WFSB is that it has co-channel interference from WCBS on the same channel. WFSB needs to be at least 16 dB stronger than WCBS for reception. Since it is in a different direction, the antenna pattern helps to make WCBS weaker.