* Mild weather this week pressures prices * Very high storage, production also weigh on sentiment * Cooler outlook for next week limits downside * Coming Up: Reuters weekly natgas storage poll Wednesday By Joe Silha NEW YORK, Dec 4 (Reuters) - Front-month U.S. natural gas futures ended lower on Tuesday for the fourth time in five sessions, undermined by record high supplies and mild weather over much of the United States this week that has slowed overall demand. "The price drivers remain the same, warm weather forecasts and nuclear generation coming back online," Gelber & Associates analyst Aaron Calder said in a report. But Calder noted the forecasts, while still above normal, are less extreme in the extended outlook than the much-above normal temperatures seen this week. While high nuclear plant outages helped lift demand for gas last month, the total at about 15,000 megawatts has dropped sharply over the last week as units return from autumn maintenance. Gas-fired plants are typically used to cover any shut nuclear units, but traders said lighter loads due to milder weather have reduced the need for replacement generation. The front-month contract, which hit a 13-month high of $3.933 per million British thermal units 10 days ago, posted a modest gain on Monday, rebounding from a technically overs old condition after sliding nearly 9 percent last week in its biggest weekly price drop in five months. Without more cold to lift demand, most traders agree any upward move in prices will be difficult, particularly with inventories still at record highs for this time of year and production flowing at or near an all-time peak. Front-month gas futures on the New York Mercantile Exchange ended down 5.2 cents, or 1.4 percent, at $3.539 per mmBtu after trading in a range of $3.525 to $3.611. MDA Weather Services expects temperatures in the Northeast and Midwest, key gas-consuming regions, to be above to much-above normal this week. The private forecaster sees cooler conditions, particularly for the Midwest, next week before readings moderate again to normal or slightly above normal. SURPRISE BUILD Data last week from the U.S. Energy Information Administration showed domestic gas inventories for the week ended Nov. 23 rose by 4 billion cubic feet to 3.877 trillion cubic feet. The build was a surprise to most traders who expected a net decline of 12 bcf, according to a Reuters poll. Traders expect storage in Thursday's report to drop below year-ago levels for the first time in 13 months. Withdrawal estimates range from 51 bcf to 90 bcf, with most in the high-60s. Stocks fell 14 bcf during the same week last year. The five-year average for that week is a 51 bcf decline. While a huge inventory surplus relative to a year ago - which peaked in early April at nearly 900 bcf - has been almost wiped out, storage is still at record highs for this time of year and offers a comfortable cushion to meet any winter spikes in demand or unexpected disruptions in supply. Stocks hit an all-time high of 3.929 tcf in early November. This is the fourth straight year that gas inventories have headed into the heating season at a record peak. RECORD HIGH PRODUCTION Baker Hughes Inc data on Friday showed the gas-directed rig count fell by four last week to 424, just above the 13-1/2-year low of 413 posted three weeks ago. Drilling for natural gas has mostly been in decline for the last year, with gas rigs down nearly 55 percent since peaking last year at 936 in October. The steep slide has stirred expectations that producers might curb record output, but so far production has not shown any significant signs of slowing. The associated gas produced from shale oil and shale gas liquids wells has kept dry gas flowing at or near a record pace. EIA data on Friday showed gross natural gas production in September rose to a record high of 73.05 billion cubic feet per day, eclipsing the previous record of 72.74 bcfd set in January.