UK GAS-Prompt prices decline on lower demand, higher Norwegian supply

April 28 (Reuters) - British prompt gas prices fell on Friday morning on lower demand and as flows from Norway increased after maintenance at the Kaarstoe processing plant ended. * The within-day contract down by 0.80 pence to 41.20 p/therm at 0919 GMT. * Day-ahead gas price 0.55 pence lower at 41.50 p/therm. * "Kaarstoe maintenance has come to an end and Norwegian gas flows are up," said a trader, adding that the system might be slightly undersupplied but it had improved from Thursday. * Maintenance at the Kaarstoe processing plant in Norway ended on Friday morning. * Flows through the Langeled pipeline from Norway are at 56 mcm, up from 52 mcm on Thursday. * Thomson Reuters (Dusseldorf: TOC.DU - news) analyst Dimitrios Saratzis said a steep increase in temperatures is expected after a cold snap ends this wekeend, which should reduce demand for heating and is bearish for prompt contracts. * Temperatures on Friday will reach 13 degrees Celsius in southern Britain, and rise to up to 16 degrees over the weekend, UK's Met Office data showed. * "However, there is a bullish risk the week after next as Ormen Lange and Troll maintenance will take place simultaneously for some days," Saratzis added. * The system was slightly undersupplied by about 2 million cubic metres (mcm), with flows forecast at 273 mcm/day and demand at 275 mcm, National Grid (LSE: NG.L - news) data shows. * Peak wind power output is forecast at 2.8 gigawatts (GW), rising to 6.3 GW on Saturday (Shenzhen: 002291.SZ - news) , National Grid data shows. * The May gas price was up 0.67 pence at 40.00 p/therm. * Day-ahead gas at the Dutch TTF hub rose by 0.23 euros to 16.38 euros/MWh. * The benchmark Dec (Shanghai: 600875.SS - news) -17 EU carbon contract gained 0.02 euros to 4.57 euros a tonne. * Thomson Reuters analyst view: http://emea1.apps.cp.extranet.thomsonreuters.biz/cms/?pageid=united-kingdom-gas (Reporting by Lefteris Karagiannopoulos in Oslo; editing by Nina Chestney)