CHICAGO, June 12 (Reuters) - Basis bids for corn and soybeans shipped by barge to U.S. Gulf Coast export terminals eased on Friday, as Chicago grain futures saw a day of short covering and extremely choppy trading ahead of the weekend, traders said.

• Chicago Board of Trade soybean and corn futures also faced pricing pressure from South American production forecasts and a slump in crude oil prices, traders said.

• In a widely followed monthly global supply and demand report, the U.S. Department of Agriculture this week increased its forecasts for this season's corn output in Argentina and Brazil, as well as soybean production in Argentina.

• In the U.S. cash grain markets, spot basis bids for corn were largely flat to higher at elevators, river terminals, ethanol plants and other kinds of processors in a spot check of locations in the U.S. Midwest on Friday.

• Empty barge freight rates have steadied on the interior rivers, but prices have remained elevated in some markets, dealers said. Exporters are mostly focused on booking barges and hunting for prices for July loadings, two dealers said. BG/US

• Brokers are closely watching storm forecasts by the National Weather Service over the next 7 to 10 days, which are expected to bring some short-term relief for water levels on the Mississippi river and its tributaries, which have been running at sharply low levels this spring, stressing barge traffic and navigation.

• CIF corn barges loaded in June were bid at 75 cents over Chicago Board of Trade July CN26 futures, down 3 cents from Thursday. July corn barges traded at 89 cents over futures, and were offered at 90 cents over futures on Thursday afternoon.

• FOB export premiums for Gulf corn vessels loaded in July held steady at around 103 cents over futures.

• For soybeans, CIF barges loaded in June were bid 76 cents over CBOT July SN26 futures, down 1 cent.

• FOB export premiums for soybean vessels loaded at the Gulf in July were unchanged, offered at around 110 cents over futures.

For displays of CIF basis, click on the codes in brackets:

U.S. CIF Gulf soybeans GRYM

U.S. CIF Gulf corn GRYN

U.S. CIF Gulf SRW wheat GRYO

U.S. CIF Gulf HRW wheat GRYP

For displays of FOB basis, please click on the following codes in brackets:

U.S. FOB Gulf corn GRZC

U.S. FOB Gulf soybeans GRZD

U.S. FOB Gulf SRW wheat GRZE

U.S. FOB Gulf HRW wheat GRZF

LINKS

Corn prices page: cpurl://apps.cp./cms/?pageid=corn-cash-market

Wheat prices page: cpurl://apps.cp./cms/?pageid=wheat-cash-market

U.S. barge freight BG/US

U.S. export sales estimates USDA/EST

U.S. grain export summary GRA/U

Brazil soybean export prices SYBS

Brazil corn export prices SYBX

Argentina grain prices GRA/ARG

Russia grain prices GRA/RU