* Front month remains well below recent 21-month high * Above-normal temperatures on tap but not extreme heat * Nuclear power plant outages remain above normal * Coming Up: EIA natgas storage data on Thursday By Eileen Houlihan NEW YORK, May 29 (Reuters) - U.S. natural gas futures slid less than 1 percent on Wednesday, extending losses for the third straight session as the June contract expired. "Natural gas has extended its recent decline, with long liquidation out of the expiring June futures contract still playing a role," said Citi Futures energy analyst Tim Evans. While above-normal temperatures remained on tap for most of the nation for the next two weeks, traders said the weather might not be hot enough to spark heavy cooling loads yet. Front-month June natural gas futures on the New York Mercantile Exchange slid 2.6 cents, or 0.62 percent, to expire at $4.148 per million British thermal units, after trading between $4.071 and $4.179. The nearby contract hit a one-month low of $3.883 on May 9 after climbing to a 21-month high of $4.444 on May 1. Other months ended lower as well, with the July contract losing 4 cents to settle at $4.184. In the cash market, gas for Thursday delivery at the NYMEX benchmark Henry Hub in Louisiana slid 4 cents to $4.15, with late deals firming just slightly to 3 cents under the June contract, from those done late Tuesday at a 4-cent discount. Gas on the Transco pipeline at the New York citygate jumped 23 cents to $4.64 ahead of much warmer weather expected in the Northeast late this week. Forecaster MDA Weather Services called for heat to build in the Northeast in its one to five-day outlook. The latest National Weather Service's six to 10-day and eight to 14-day outlooks, both issued on Tuesday, again called for above-normal temperatures for most of the nation. Nuclear plant outages totaled 15,700 megawatts, or 16 percent of U.S. capacity, up from 14,700 MW out on Tuesday and a five-year average outage rate of 14,300 MW, but down from nearly 16,000 MW out a year ago. Injection estimates for this week's gas storage report from the U.S. Energy Information Administration ranged from 80 billion cubic feet to 97 bcf, with most traders and analysts expecting data to show a build of 88 bcf when it is released on Thursday, a Reuters poll showed. Stocks rose an adjusted 72 bcf in the same year-ago week, and on average over the past five years have gained 92 bcf that week. The EIA will release its gas storage data for the week ended May 24 at its usual time, Thursday at 10:30 a.m. EDT (1430 GMT), despite the U.S. Memorial Day holiday on Monday.