Soy prices slide on U.S. crop forecast; corn also falls

* Soybean prices fall after USDA raises U.S. crop forecast

* Forecasts of improved crop weather this week add pressure

* Grains weighed by improved outlook for Ukraine exports

LONDON, Aug 15 (Reuters) - Chicago soybeans slid almost 3% on Monday, falling for the first time in three sessions after a U.S. government report raised the country's production forecast, with additional pressure from expectations of improved weather this week.

Corn and wheat prices also fell sharply.

"Traders were expecting a cut in soybean production but the USDA (U.S. Department of Agriculture) raised production and yield to record highs," according to a Hightower report.

"The report news was bearish, especially the jump in yield as acreage was adjusted lower. Traders also see the cooler and wetter weather expected this week as a bearish factor."

The most-active soybean contract on the Chicago Board of Trade lost 2.7% to $14.15-1/2 a bushel by 1014 GMT.

U.S. soybean production will be bigger than previously forecast as better-than-expected yields will more than make up for a cut to acreage, the U.S. government said on Friday.

CBOT corn prices also fell with the most active contract down 2.5% at $6.26-1/4 a bushel.

Dealers noted the USDA raised its forecast for Ukraine corn production and exports in its report on Friday as the market digests the grain deal with Russia which has allowed some shipments to leave its ports.

"There is still plenty of uncertainty over how Ukrainian export volumes will evolve, despite the Ukraine/Russia grain deal," ING said in a note.

Two more ships carrying grain left from Ukraine's Black Sea ports on Saturday, bringing the total number of vessels to depart the country under a U.N.-brokered deal to 16.

Ukraine's grain exports are down 46% year on year at 2.65 million tonnes so far in the 2022/23 season, the agriculture ministry said on Monday.

CBOT wheat prices also fell with the most active contract down 2.4% at $7.86-1/2 a bushel. (Additional reporting by Naveen Thukral in Singapore; Editing by Kirsten Donovan)