Natural gas futures moved fractionally higher Thursday as market participants await government storage data and track Hurricane Irene as takes aim at major East Coast power markets.

Natural gas for September delivery recently traded 0.4 cents, or 0.1%, higher, at $3.926 a million British thermal units on the New York Mercantile Exchange.

After trading near $5/MMBtu earlier in the summer, when unseasonably high temperatures across the U.S. lifted demand, the benchmark contract has traded below $4/MMBtu in 15 of the last 16 sessions.

The morning's "subdued" trading "won't last for long" as the Energy Information Administration's weekly storage report will "likely elevate volatility to a much higher level," Galena, Ill., trading advisory Ritterbusch and Associates said in a note to clients. "We are looking for a bearish figure in this report one that could prove capable of slamming nearby futures into new low territory, possibly to the $3.75-3.80 zone."

The EIA is scheduled to release its storage data for the week ended Sept. 19 at 10:30 a.m. EDT.

The agency is expected to report that U.S. stockpiles grew by 73 billion cubic feet, according to a Dow Jones Newswires survey of analysts and traders.

Such a build would nearly double last year's for the same week, which was 38 bcf, and be well higher than the five year average of 55 bcf.

If survey estimate is correct, U.S. gas in storage as of Friday would have been 2.906 trillion cubic feet, 1.8% below the five-year average and 4.6% lower than 2010 levels.

Inventories reached a record in November of 3.84 trillion cubic feet, but frigid weather lifted heating demand in the following months and eliminated the surplus compared with average levels. Unseasonable heat earlier this summer helped maintain the storage deficit, but strong production, particularly from onshore shale formations, is expected to close the gap as temperatures moderate in many large power markets.

Private forecasters Commodity Weather Group predict a "surge in heat" in the Midwest next week, but said that any added demand to power air conditioners in Chicago could be negated by the effects of Hurricane Irene, which could knock out power in major cities like Boston and Washington, D.C. this weekend or early next week.

"Extensive power outages could suppress East Coast demand well into next week," the meteorologists said.