Causal factors are so variable I wouldn't give a lot of credence to the fixed time cycle unless you can pin down a very specific event like sunspot activity. A saturated countryside helps more rain to be likely Highs tend to persist over land masses. Things like rising ground help clouds to form Most humidity is from Tropical Maritime sources. Polar air is very dry. You won't get floods from there but a cold front cools and slides under hot air and if THAT air is moist you get high lapse rates and convective clouds, storms and HAIL. Nev