After rain signal lost

After a lengthy rain the signal is lost for several hours.  It can be clear skies and the signal will show zero strength.  We have two dishes...one for local channels and one for upper channels.  Tonight (clear skies after a rain two hours ago) the local channels are working...upper channels are not.  Says searching for satellite signal.  It has only been happening in the last month-third time.  If it holds true to last time, the signal will be working in the morning. Clouds are not an issue after the rain.  Is there a short in the cables?  The receiver is about 7 years old.  I was told DirecTV would not replace or update the receivers.  What can I check?