Abstract
Diurnal variation of precipitation in the warm season (June-September) in Japan is described by using data at 1,234 stations on an automated rain-gauge network. Local precipitation and widespread precipitation are separately analyzed. Diurnal variation of thunderstorm frequency is also described by use of data at 85 observatories.
Local precipitation and thunderstorms exhibit a pronounced maximum between 1500 and 1800 local time in the inland areas. Time of maximum differs by a few hours according to regions and local topography. On the other hand, 0300-0600 maxima prevail at maritime stations on islands and peninsulas, except for the Nansei Islands where a 1200-1500 maximum occurs at relatively large islands.
Widespread precipitation shows a pervasive signal of weak maximum in early to middle morning, except that a maximum tends to occur around noon over the Nansei Islands.
