* Rains provide U.S. corn, soy crops some relief

* Longer term forecast turns drier, raising worry about soy

* Soybeans also lifted by renewed demand from China

* Wheat mixed on U.S. winter crop harvest, spring wheat drought

CHICAGO, June 21 (Reuters) - U.S. soybean futures advanced on Monday on renewed buying by China and as concerns lingered about dry conditions in western portions of Midwest farm belt despite scattered storms over the weekend.

Corn futures were mostly lower as rain in the central corn belt boosted crop prospects, while wheat was mixed amid winter crop harvest pressure and worries about the drought-hit spring crop.

"We got a lot of rain over the weekend in some areas. While that's certainly beneficial, the longer term forecasts - the 6-10 day, the 10-14 day - have gotten a bit drier, especially in the western half of the corn belt," said Ted Seifried, chief ag strategist with the Zaner Group.

"The rain was probably more beneficial for the corn. The beans are going to need more rain later on," he said.

Grain traders are closely watching Midwest weather forecasts as drought has been creeping into western and northern production areas, including in major producer Iowa.

The U.S. Department of Agriculture (USDA) is due to update its weekly crop condition ratings later on Monday, with analysts, on average, expecting the share of corn and soybeans rated good to excellent to drop by 2 percentage points due to stressful Midwest weather last week.

Soybean futures also drew support from USDA confirmation on Monday of renewed buying by China, first reported by Reuters on Friday, the country's largest scale purchases in 4-1/2 months.

Chicago Board of Trade July soybeans were up 19 cents at $14.15 a bushel, while new-crop November soybeans were up 6-1/4 cents at $13.19-1/4 a bushel.

July corn gained 4 cents to $6.59-1/4 a bushel, while new-crop December fell 9-1/4 cents to $5.57 a bushel.

CBOT July soft red winter wheat ended down 1-1/4 cents at $6.61-1/2 a bushel. (Additional reporting by Nigel Hunt in London and Colin Packham in Canberra, Editing by Sherry Jacob-Phillips, Steve Orlofsky and Richard Chang)