Calculating a planet's mass & gravitational pull

[Suicide Junkie]

The stuff above you will cancel out with the stuff at the same height on the other sides of the planet.
The stuff above your horizon pulls you away, while the stuff below your horizon at the same altitude pulls you towards (weaker due to distance, but more mass) Given reasonably constant density from one side to the other, it cancels out.

Stormy weather would make for small differences.
Sunlight heating one side would make for bigger differences.
But the density can't vary by that much, since the high pressure air will just blow into the low pressure zone and equalize it.