NEW YORK – Most commodities prices advanced Wednesday, lifted by the rising price of oil as traders eyed the trajectory of Tropical Storm Gustav.

The storm, though downgraded from hurricane status, appeared headed for the Gulf of Mexico, where key oil facilities are located. Back in 2005, hurricanes Katrina and Rita temporarily halted nearly all production in the region.

But with the dollar mixed and trading volumes thin ahead of the Labor Day holiday weekend, some metals and grains ended on a weak note.

Oil prices rose for the third consecutive session, shrugging off an Energy Department report showing an unexpected drop in U.S. crude supplies. Royal Dutch Shell PLC and BP PLC said they have started evacuating some workers from offshore rigs in the Gulf.

Light, sweet crude for October delivery rose $1.88 to settle at $118.15 a barrel on the New York Mercantile Exchange. Heating oil futures rose 5.18 cents to finish at $3.2617 a gallon, while gasoline futures gained rose 9.75 cents to close at $3.0672 a gallon.

Natural gas is another type of energy with significant production facilities in the Gulf – natural gas futures rose 11.6 cents to end at $8.394 per 1,000 cubic feet on Nymex.

In the agriculture markets, the major grain products finished mixed. Grains were subject to many crosscurrents on Wednesday – rising oil prices, a wavering dollar, and weather forecasts for rain.

“We look forward to the harvest with a lot of uncertainty,” said Elaine Kub, analyst with DTN in Omaha, noting that the U.S. Department of Agriculture's weekly reports late in the season are not as helpful as they tend to be earlier in the season. “We're kind of blind for a while until we get into harvest.”

Wheat for December delivery fell 28.75 cents to finish at $8.2575 a bushel; December corn added 2 cents to end at $5.96 a bushel; and November soybeans rose 3.5 cents to close at $13.48 a bushel.

Metals were mostly higher, but lost momentum later in the day, which dragged silver prices into negative territory.

Gold futures for December delivery rose $5.90 to settle at $834 an ounce on the New York Mercantile Exchange, extending Tuesday's modest gain.

September silver fell 10.5 cents to settle at $13.47 an ounce on the Nymex, where December copper rose 2.85 cents to settle at $3.445 a pound.