UK GAS-Prompt softens as Norwegian exports set to rise, demand ebbs

LONDON, May 19 (Reuters) - British wholesale gas prices fell on Friday due to lower demand forecasts for next week and expectations of higher Norwegian supply as maintenance at the Troll gas field is set to end. * British day-ahead gas price down by 1.85 pence or to 38.65 pence per therm at 0939 GMT. * Within-day contract 0.40 pence lower at 40.30 pence per therm. * Traders said expectations of lower demand on Monday, as well as rebounding supply from Norway once the Troll gas field resumes production on Saturday (Shenzhen: 002291.SZ - news) , was keeping a lid on prices. * One trader added that with stronger European coal futures and Brent crude oil continuing to build on recent gains, UK gas prices may find greater support later in the session. * Average temperatures on Monday could reach 15.1 degrees Celsius Britain, Reuters data showed, up to 3.5 degrees higher than initially expected. * Gas deliveries from Norway through the Langeled pipeline, down by 5 million cubic metres/day at 26 mcm/day, are due to rebound by Monday as maintenance on the Troll gas field will end this weekend, analysts said. * A new liquefied natural gas (LNG) delivery due at Milford Haven on June 2 further alleviated supply concerns. * However, the UK gas system was undersupplied by 10.8 million cubic metres/day (mcm) with demand forecast at 198.8 mcm and flows at 188.9 mcm, National Grid (LSE: NG.L - news) data shows. * Further along the curve, the June gas contract was up by 0.08 pence at 37.53 p/therm. * Day-ahead gas price at the Dutch TTF hub inched up by 0.03 euro to 15.63 euros per megawatt hour. * Benchmark Dec-17 EU carbon contract up by 0.07 euro to 4.83 euros a tonne. * 2018 European thermal coal futures up 1.23 percent to $65.85 a tonne; Brent crude oil prices up $0.78 a barrel to $53.27 a barrel. * Thomson Reuters (Dusseldorf: TOC.DU - news) analyst view: (Reporting by Oleg Vukmanovic; editing by Nina Chestney)