The website you are referring to is located at:
http://www.antennaweb.org/aw/Address.aspx - but be careful using this
site. With your zip code, you might get the idea that your local
stations and the San Francisco stations are in the same direction. NOT
SO. They list so many channels in that same GENERAL direction that you
really can't decipher from that website which direction the signal is
coming from.

The Sacramento and San Francisco stations are NOT located in the exact
same direction. That is why you need a highly directional antenna with
a very narrow beamwidth. You can separate the locals from the Bay Area
stations. You can "pick up" the San Francisco stations when the
antenna is pointed towards the Sacramento towers, but you can get a
STRONGER signal when turning the antenna towards Mt. Sutro (San
Francisco towers), and at the same time, REDUCE the local signals, thus
giving you a stronger signal with less interference. To help clear up
the confusion between coax and twin lead -- First, twin lead must be
installed properly - not touching any metal to say the least, as it
should be a few inches from any metal. It's not good to install twin
lead between walls, etc. As far as loss goes, coax is consistant
regardless of the weather. Twin lead losses can be greater than coax
during wet or damp weather. To have low loss, twin lead must be dry.
Also, twin lead is more suseptible to breakage during high winds. You
want the SAME lead in all the way from the antenna to the television.
Don't mix twin lead with coax. You might get excellent reception of
the local channels, but it can make a big difference on distant
reception. IF your antenna is high gain on UHF, has good directional
characterics, you should easily get channel 19 from Modesto UNLESS
there is a mountain near you blocking signals from that direction.
However, channel 14 in San Francisco is also Univision. I have picked
up weak signals from channel 14 even here in Fresno. I can tell you
this - When living in Fair Oaks, I had the largest Channel Master
UHF/VHF antenna available, installed on a 40-ft mast with rotor and I
could NOT get any signal on channel 14. But my neighor had a cheap,
small antenna mounted on the chimney and got a good signal on channel
14. Higher is not always better on UHF. Also, ANY bad balum OR even
twisting wires combining coax to twin line can totally wipe out some
UHF frequencies.