Adds latest prices

By Scott DiSavino

June 27 (Reuters) -U.S. natural gas futures slid about 2%on Thursday on arise in output and forecasts for less demand next week than previously expected.

That price decline cameeven though last week's storage build was smaller than usual for this time of year for a seventh week in a row and theheat wave blanketing much of the countrywill likely remain in place through at least mid-July. That heat should force power generators to continue burning lots of gas to keep air conditioners humming.

Traders said recent storage builds have been smaller than usual because several producers cut output earlier in the year after futures prices dropped to 3-1/2-year lows in February and March. Higher prices in recent weeks, however, have prompted some producers, including EQT EQT.N and Chesapeake Energy CHK.O, to return to the well pad.

The U.S. Energy Information Administration (EIA) said utilities added 52 billion cubic feet (bcf) of gas into storage during the week ended June 21.

That was close to the 51-bcf build analysts forecast in a Reuters poll and compares with an increase of 81 bcf in the same week last year and a five-year (2019-2023) average rise of 85 bcf for this time of year. EIA/GAS NGAS/POLL

Even though storage builds have been smaller than average in recent weeks, the amount of gas in storage was still around 21% higher than usual for this time of year.

On their first day as the front-month, gas futures NGc1 for August delivery on the New York Mercantile Exchange fell 6.0 cents, or 2.2%, to settle at $2.685 per million British thermal units (mmBtu).

In Texas, the power grid operator for most of the state projected peak demand would break the record for the month of June on Thursday as homes and businesses crank up their air conditioners to escape the heat.

SUPPLY AND DEMAND

Financial firm LSEG said gas output in the Lower 48 U.S. states roseto an average of 98.6 billion cubic feet per day (bcfd) so far in June, up from a 25-month low of 98.1 bcfd in May. That compares with a monthly record high of 105.5 bcfd in December 2023.

Meteorologists projected weather across the Lower 48 states would remain hotter than normal through at least July 12.

But with less heat forecast next week, LSEG forecast average gas demand in the Lower 48, including exports, will slide from 102.9 bcfd this week to 99.9 bcfd next week. The forecast for next week was lower than LSEG's outlook on Wednesday.

Gas flows to the seven big U.S. LNG export plants eased to 12.8 bcfd so far in June, down from 12.9 bcfd in May and a monthly record high of 14.7 bcfd in December 2023.

Feedgas to the 2.1-bcfd Freeport, one of the most watched U.S. LNG plants because it has a history of swaying global gas prices when it shuts, was on track to rise to 1.9 bcfd on Thursday after dropping to a seven-week low of 1.5 bcfd on Tuesday. Freeport told Texas environmental regulators that the second of three liquefaction trains tripped on Tuesday due to an issue with a power feed.

In other LNG news, Venture Global's Plaquemines export plant under construction in Louisiana started to take in pipeline gas on Wednesday, signaling the plant was on track to produce its first LNG later this year as expected.

Separately, U.S. energy regulators approved Venture Global's request to build the CP2 LNG export plant in Louisiana.

Reporting by Scott DiSavino; Editing by Paul Simao and Nick Zieminski

For gas data on LSEG's Eikon type ENERGY in the search bar and then go to the GAS drop down and the NORTH AMERICA drop down.

For Interactive Map, type 'Interactive Map' in the box at upper left of the Eikon terminal

For graphics on Baker Hughes rig counts, see: http://graphics.thomsonreuters.com/15/rigcount/index.html

For next-day SNL U.S. gas prices, see: 0#SNL-NG

For next-day SNL U.S. power prices, see: 0#SNL-PWR

For U.S. natgas price and storage polls, see: NGAS/POLL

For U.S. nuclear power outages, see: NUKE/

For U.S. Northwest hydro power report, see: NWRFC

For U.S./Canada natural gas rig count vs Henry Hub futures price, see: http://tmsnrt.rs/2eT9k44

For the U.S. natural gas speed guide, see: USGAS

For the U.S. power speed guide, see: USPOWER

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NYMEX Henry Hub options and futures combined 0#3CFTC023651

NYMEX Henry Hub futures only 0#1CFTC023651

ICE Henry Hub options and futures combined 0#3CFTC023391

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NYMEX Henry Hub Penultimate gas swaps 0#3CFTC03565C