Prices are firmer this morning with ratings slipping more than expected providing a fairly typical turn-around Tuesday trade.   WEATHER Temperatures will turn hotter this week, but there is enough generalized rainfall around right now, with better chances of rainfall July 25-29.  There is adequate moisture for most of the western Midwest in order to foster growth.  The eastern Corn Belt received good coverage over the weekend.  A ridge will build over the country this week and will bring with it hotter and drier conditions for some, particularly to southern and eastern parts of the Midwest.  Shower coverage in the Delta could become more isolated as hot and dry conditions occur.  Prices will react if the...