GRAINS-Wheat and soybeans fall again as supply outweighs weather risks

* Wheat, soybeans lower for third straight session

* Wheat retreats from this week's multi-month highs

* Poor U.S. crop ratings put floor under wheat market

* Soy weak on Argentine weather hope, slow U.S. exports

(Updates with European trading, changes byline/dateline) PARIS/SINGAPORE, Feb 2 (Reuters) - Chicago wheat and soybean futures slid for a third session on Friday, with abundant supplies and stiff export competition tempering concern about harsh crop weather in the United States and Argentina. Concern about drought damaging the U.S. winter crop, which drove prices to a multi-month high this week, were still underpinning prices, but analysts said it was too early to assess potential damage. "We won't know about the yield prospects until the last of the snow melts," said Phin Ziebell, agribusiness economist at National Australia Bank. "Globally there is no worry about supplies as of now." A tender by Egypt on Thursday confirmed strong competition from Black Sea origins despite uncertainty over changes to terms by Egyptian state buyer GASC.

Russia is on course for record grain exports this season, helped by a bumper wheat harvest and mild winter weather, analysts and industry players said.

The Chicago Board of Trade's most-active wheat contract was down 0.6 percent at $4.48-1/4 a bushel by 1254 GMT but was still heading for a third consecutive weekly gain. CBOT soybeans were down 0.5 percent at $9.80-1/4 a bushel while corn eased 0.1 percent to $3.77-1/2. "South American weather now has hit-and-miss rainfall later next week in Argentina, with limited rainfall in Brazil early next week too," British merchant Gleadell said in a note. The forecasts for rain and less intense heat have eased jitters about drought damage in Argentina, while a drier outlook in Brazil could help harvesting of what is expected to be another bumper crop. Broker and consultancy INTL FCStone on Thursday raised its Brazilian soybean harvest forecast to 111.08 million tonnes, up by about 1 million from its January outlook. The soybean market is facing pressure from lacklustre demand for U.S. cargoes. U.S. soybean export sales fell to a seven-month low last week, according to government data released on Thursday, as stiff competition from rival exporter Brazil and concerns over lower U.S. crop quality dented demand.

Weekly corn exports, however, topped trade expectations, with net sales of nearly 1.9 million tonnes last week.

Prices at 1254 GMT

Last Change Pct End Ytd Pct Move 2017 Move CBOT wheat 448.25 -2.75 -0.61 427.00 4.98 CBOT corn 377.50 -0.25 -0.07 350.75 7.63 CBOT soy 980.25 -4.75 -0.48 961.75 1.92 Paris wheat Mar 156.50 0.25 0.16 159.00 -1.57 Paris maize Mar 151.75 -0.50 -0.33 157.75 -3.80 Paris rape Feb 343.25 -3.00 -0.87 352.75 -2.69 WTI crude oil 65.67 -0.13 -0.20 60.42 8.69 Euro/dlr 1.25 0.00 -0.16

Most active contracts - Wheat, corn and soy US cents/bushel, Paris futures in euros per tonne

(Reporting by Naveen Thukral in Singapore and Gus Trompiz in Paris; Editing by Joseph Radford and David Goodman)