(Updates with U.S. trading, adds new analyst quote, changes byline, dateline; pvs PARIS/MANILA)
CHICAGO, Aug 18 (Reuters) - U.S. corn, soybean and wheat futures firmed slightly on Friday, but outlooks for good weather for crop development limited attempts at a rally, traders said.
As a result, all three commodities were on track to post weekly losses.
"Ongoing pressure from large supplies and lack of a weather threat kept markets on the defensive this week," Farm Futures analyst Bryce Knorr said in a note to clients.
At 10:13 a.m. CDT (1513 GMT), Chicago Board of Trade (CBOT) November soybean futures were up 1-1/4 cents at $9.34-1/4 a bushel.
CBOT December corn was 3/4 cent higher at $3.65 a bushel and September wheat futures were up 1-1/2 cents at $4.15-1/2 a bushel.
"Wheat prices are trying to stabilize," consultancy Agritel said in a research note. "The current level of prices is triggering some bargain buying."
For the week, wheat was off 5.2 percent, soybeans were down 1.1 percent and corn was down 2.5 percent.
Seasonal supply pressures from big harvests in Russia and elsewhere in the Black Sea export region, along with chart-based selling momentum pushed wheat futures in Paris to new lows on Friday.
Weather forecasts looked relatively favorable for Midwest corn and soybean crops, although there was still uncertainty as to whether showers would reach all of the areas affected by very dry conditions earlier this summer.
"Grain prices will trade largely sideways in the coming weeks as wheat harvests are nearly finished and weather conditions remain favorable for upcoming Northern Hemisphere corn and soybean harvests," BMI Research analysts said in a note.
The weather forecast also added pressure to the wheat market as rain was expected to recharge soil moisture in winter wheat areas ahead of planting this fall.
Soybeans have been underpinned this week by renewed export demand, suggesting a window for U.S. exports despite record harvest supplies in rival exporter Brazil. (Additional reporting by Manolo Serapio Jr. in Manila and Gus Trompiz in Paris; editing by Greg Mahlich and G Crosse)