* Delayed spring plantings causing acreage shift
* USDA to release crop data at 12:00 p.m. EDT (1600 GMT
By Sam Nelson
CHICAGO, June 12 Rainfall in the U.S. Midwest will continue to slow late plantings of corn and soybeans, but the moisture will boost growth and development of crops that have been planted, an agricultural meteorologist said on Wednesday.
"There will be frequent storms for the next week to 10 days, bringing pretty much excellent conditions for crop development, but it will slow late plantings," said Andy Karst, meteorologist for World Weather Inc.
Karst said farmers would have several brief windows of opportunity to plant their remaining corn and soybean crops. Because of excessive wet weather this spring, planting has hit its slowest pace since the mid-1990s, causing a shift away from corn acreage to soybeans.
Grain analysts polled by Reuters on Tuesday estimated that the U.S. Department of Agriculture on Wednesday would reduce its 2013 U.S. corn plantings forecast by nearly 1.5 million acres and raise soybean acreage 700,000 due to persistent spring rains.
The USDA currently estimates U.S. corn planted acreage at 97.3 million, which is the most since the 1930s.
The USDA will release its June supply/demand and global crop production report at 12:00 p.m. EDT (1600 GMT) on Wednesday and on June 28 will release its updated quarterly grain stocks report and an updated U.S. acreage report.
The USDA said on Monday that rains and cool temperatures had slowed planting and development of crops.
Soybean planting progress reached 71 percent on Sunday, the USDA said, up from 57 percent a week earlier, but behind the five-year average of 84 percent.
Corn planting was 95 percent complete, up 4 percentage points from the prior week and lagging the five-year average of 98 percent.
The pace for both crops was the slowest since 1996, when farmers had seeded just 92 percent of their corn and 59 percent of their soybeans by this time of year. The figures were in line with a Reuters survey of analysts conducted ahead of the report. (Additional reporting by Julie Ingwersen and Mark Weinraub; Editing by Lisa Von Ahn)