* Front-month futures close below 100-day moving average * High storage, production weigh on prices By Joe Silha NEW YORK, Jan 28 (Reuters) - Front-month U.S. natural gas futures ended lower for a fifth straight day on Monday, undermined by milder Northeast and Midwest weather this week that should slow heating demand. While colder temperatures are expected to return to both regions later this week and early next week, traders also noted that the extended, or 15-day, outlook had turned warmer. "On Friday, it looked like we were in for some real cold, but that forecast evaporated today. We lost the weather (cold forecast), so the market tanked," a Texas-based trader said. Front-month February gas futures, which expire on Tuesday, ended down 15.5 cents, or 4.5 percent, at $3.289 per million British thermal units on the New York Mercantile Exchange after trading between $3.285 and $3.396. The front month, which hit a 6-1/2-week high of $3.645 early last week, has lost 7.8 percent in the last five sessions as weather forecasts moderated. That marks the biggest five-day slide in nearly seven weeks. Technical traders noted the front contract gapped lower on Monday and closed below the 100-day moving average in the $3.40 area, a possible bearish sign that could signal more downside. In its morning report, MDA Weather Services said the 11-to-15-day forecast included some "major warm changes" on Monday, noting computer models show warmth expanding from the South. While gas prices could garner some support from nuclear plant outages, which are running at about 9,000 megawatts this week, or 2,700 MW above average, few traders expect much upside with inventories high and production flowing at or near a record pace. BIG STORAGE DRAW FAILS TO FIRM PRICES U.S. Energy Information Administration data on Thursday showed domestic gas inventories for the week that ended Jan. 18 had fallen by 172 billion cubic feet to 2.996 trillion cubic feet. Most traders viewed the decline as supportive, noting it topped market expectations for the fourth straight week, but inventories are still hovering at 320 bcf, or 12 percent, above the five-year average despite recent strong pulls from storage. Early withdrawal estimates for Thursday's inventory report range from 197 bcf to 210 bcf. That would be well above the 149 bcf drawn from inventory during the same week last year and the five-year average decline of 178 bcf for that week. If drawdowns for the rest of winter match the five-year average, inventories will end March at 2.048 tcf, about 18 percent above normal but 17 percent below last year, when stocks finished a very mild heating season at a record-high 2.48 tcf. GAS RIG COUNT GAINS, FIRST TIME IN 3 WEEKS Baker Hughes data on Friday showed the gas-directed drilling rig count gained last week for the first time in three weeks, rising by five to 434. Drilling for natural gas has mostly been in decline for more than a year. The gas rig count is not far above the 13-1/2-year low of 413 posted in early November, but so far production has shown no significant sign of slowing. The EIA estimates that gas output in 2013 will hit a record high for the third straight year.