Rain fade is largely dependent on the frequency. A lot of satellite is now Ka band which is a very high frequency range (literally not VHF) and the rain drops cause attenuation and scattering. The attenuation and scattering will cause the signal level to drop and the noise floor to rise, effectively lowering your signal to noise ratio Alignment isn't as touchy these days with antennas that look at multiple satellites. If there is an alignment issue, look up which channels are fading in and out and see if they are on a common satellite. If so, there could be an azimuth alignment issue. If they are all fading, it's either an elevation alignment issue or rain fade.
Most of my experience comes from much larger, higher gain antennas with very sensitive alignment characteristics due to small beamwidths. That are designed to look at one orbital slot. So take my alignment advice of a small TV antenna meant to look at 30 degrees worth of orbital slots with a grain of salt. It is important to note that when you peak up on a particular satellite, that you don't want to peak up on a sidelobe. There is a small peak and the a deep valley (null) before you reach the actual peak. So you might start to see the signal go up, then drop back down rapidly, then it will start going up higher when it finds the main beam.
This is an example of what I'm talking about. The Y-Axis is signal level as you move past the satellite in Azimuth or Elevation. X-Axis represent the movement in Azimuth or Elevation.
There are some great website and phone apps that will help you determine the best elevation and azimuth for the particular satellite combo you are looking for. Just make sure to keep your compass far away from metal objects and account for declination.
