* Revision to corn crop forecast a minor adjustment
* Effects of drought become clear now harvest under way
* Planting of winter corn crop well advanced vs 2011
SAO PAULO, March 5 (Reuters) - Brazil's 2011/12 corn harvest should turn out 60.4 million tonnes, local analyst Celeres said on Monday, trimming its view slightly from the 60.58 million tonnes it forecast in February.
Analyst estimates for corn had been slashed recently after a harsh dry spell destroyed some of the corn in top producer Parana state. Many forecasts then swung higher on expectations the winter crop, one of two annual harvests, would be bigger than previously thought.
Celeres estimates that Brazil produced 53.74 million tonnes from both summer and winter crops last season. The summer crop runs roughly from September to April with the planting of the winter crop coming straight after.
The small adjustment to Celeres' number appeared to be more a case of fine-tuning than a significant change in its outlook for the crop. Though drought conditions have eased, data from forecaster Somar showed key grains states were much drier than the historic average in February.
"The effects of the drought that took place at the end of last year in the southern region of the country are starting to become clear, with productivity turning out lower than initially expected for the current crop," Celeres said in a statement.
The analyst said 25 percent of the summer crop has been harvested, up from the 18.3 percent collected this time last year in main soy regions. The larger summer crop is seen at 34.76 million tonnes, up 5 percent from 33 million tonnes last year.
The winter crop that is planted as the summer corn and soy crop is harvested is seen at 25.6 million tonnes, up nearly 24 percent from the 20.7 million tonnes harvested last year from the second crop. Celeres said that crop was now 60 percent planted, well up from the 40 percent sown by this time last year.
Celeres revised its outlook for soy production to 69.8 million tonnes from 72 million tonnes in early February. (Reporting by Roberto Samora; Writing by Peter Murphy; Editing by David Gregorio)