UPDATE 2-Consol expects quarterly loss on coal mine output cuts

* Expects to post a third-quarter loss

* Hurt by mine idlings, lost production

* Stock down 1.45 percent

Oct 15 (Reuters) - Coal and natural gas producer Consol Energy Inc warned on Monday that it expects to post a third-quarter loss as a result of idling several mines and cutting production in response to weak coal prices.

It said it mined about 20 percent less coal in the third quarter than in the second, but expects production to be up again in the fourth quarter when its big Buchanan mine in Virginia reopens.

The company gave no figure for the anticipated loss, but Wall Street analysts had been expecting a profit of 35 cents per share, according to Thomson Reuters I/B/E/S.

Consol's stock fell on the news and in midday trading on the New York Stock Exchange, the shares were down 1.45 percent at $34.63.

Analyst Mark Levin, of BB&T Capital Markets, cut his third- and fourth-quarter earnings estimates for Consol for the second time in a week.

"If it could go wrong, it did," Levin wrote in a research note. "After...a quarter riddled with planned and unplanned outages, it should come as little surprise that the third quarter was about as bad as it gets on the coal side.

"In short, quarterly production was far worse than we expected, even though we slashed estimates just a week ago."

Levin noted Consol's coal production of 11.6 million tons in the quarter was way below his estimate of 13.9 million, and much less than the 14.6 million produced in the second quarter.

He lowered his third-quarter estimate to a loss of 20 cents per share from a profit of 23 cents. For the fourth quarter, he cut the earnings estimate to 12 cents per share from 19 cents.

Last month, Pittsburgh-based Consol said it would temporarily idle its Buchanan mine in southwestern Virginia, one of its biggest mines, due to weak global demand for steel, which has sent metallurgical coal prices down sharply. Consol also idled part of its Amonate Mining Complex in southern West Virginia.

"While precise figures are not yet available, it is clear that the company's previously announced planned and unplanned mine idlings took their toll on third-quarter earnings," Chief Financial Officer William Lyons said Monday's statement.

The company, which is scheduled to report third-quarter financial results on Oct. 25, has also been hurt by plummeting thermal coal prices because of low demand from electricity producers as some of them have switched to cheaper natural gas.

The weak thermal coal market, which has seen prices drop some 20 percent, forced Consol to temporarily idle its Blacksville, Robinson Run and Fola mines in West Virginia during the last several months.

Production was also hit after two conveyor belts collapsed in July at the Bailey coal preparation plant in Pennsylvania, affecting its Enlow Fork and Bailey mines.

Consol produced 11.6 million tons during the third quarter, lower than the 14 million to 14.5 million tons it had expected. It forecast fourth-quarter production of between 13.4 million and 13.8 million tons, including 600,000 tons at Buchanan, which is expected to restart production in the week of Nov. 5.