* Weekly US export sales disappoint traders

* Kansas wheat tour projects yields up from last year.

* Russia says frosts kill 1% of wheat crop

CHICAGO, May 16 (Reuters) - Chicago Board of Trade soybean futures ended mixed on Thursday as renewed worries about major flooding in southern Brazil offset data indicating lower demand for soy from U.S. processors, analysts said.

Corn and wheat meanwhile dipped on disappointing U.S. export sales numbers.

Soybean futures got a boost from concerns about production losses in Brazil's Rio Grande do Sul, following massive flooding in the state, said Jim McCormick, cofounder of AgMarket.net.

The issue "seemed to move to the back burner," said McCormick, but "it seems to be coming to the forefront again."

Soft domestic demand hung over the market. On Wednesday, the National Oilseed Processors Association said U.S. soybean crushings dropped to 166.0 million bushels in April, a seven-month low that was below all trade estimates.

The July soybean contract on the Chicago Board of Trade settled up 2-3/4 cents at $12.16-1/4 a bushel. New-crop contracts all were lower.

CBOT July wheat dropped 2-1/2 cents to $6.63-1/4 a bushel, while July corn lost 5-1/2 cents to $4.57 a bushel.

Wheat bumped up against technical resistance after reaching 10-month highs this week due to poor crop weather in top-exporter Russia, McCormick said.

Russia's agriculture ministry said frost killed about 1% of the country's total.

The Wheat Quality Council's annual Kansas wheat tour estimated Kansas wheat's yield potential at 46.5 bushels per acre (bpa) after scouting 449 fields over three days. The figure is the highest since 2021 and falls above the five-year tour average of 42.4 bpa from 2018-2023.

The U.S. Department of Agriculture reported export sales of new-crop U.S. wheat last week at 304,300 metric tons and old-crop U.S. corn at 742,200 metric tons, both near the low end of trade expectations.

Weekly export sales of old-crop U.S. soybeans were 265,700 metric tons, below trade expectations.

(Reporting by Renee Hickman in Chicago; Additional reported by Peter Hobson in Canberra and Sybille de La Hamaide in Paris)