Prices have soared as natural gas inventories, at a record high in mid-November, slipped below their normal early-winter level.

Natural gas inventories were 10 percent below the level a year earlier as of Dec. 13, the gas association reported last week.

But rising gas inventories caused prices to decline, putting Amaranth on the wrong side of a brutal and accelerating market trend.

Natural gas inventories trail last year's levels by 5.2 percent.

The perceived problem of large gas inventories overhanging the market and keeping down prices did not begin to disappear until the late 1990s.

With gas inventories high, prices plunged.

Mild weather and a recent rise in stockpiles are reducing concern that gas inventories will be low next winter.

The increased demand comes at a time when gas inventories in the United States are 36 percent below last year.

Swelling domestic oil and gas inventories drove down oil prices.

Natural gas inventories themselves are near six-year lows.