UK GAS-Prices mixed, driven by weather forecasts

LONDON, March 21 (Reuters) - British wholesale gas prices were mixed on Wednesday morning as forecasts of milder temperatures in the coming days dragged down the within-day price and other prompt contracts were lifted by a colder longer-term forecast.

* Within-day gas price down 0.50 pence at 57.00 p/therm, by 0857 GMT.

* Day-ahead gas price up 0.70 pence at 57.50 p/therm and working days next week contract up 1.75 pence at 55.75 p/therm.

* "The system looks comfortable today but further out it's forecast colder," a gas trader said.

* Gas system almost balanced, with demand forecast at 304 million cubic metres (mcm) and flows at 304.7 mcm/day, National Grid (LSE: NG.L - news) data showed.

* April contract up 0.50 at 51.95 p/therm, on expectations of cooler weather than previously forecast.

* "The latest EC12 ENS (temperature model) daily forecast for LDZ (local distribution zone) consumption brings a slightly downright correction for a remainder of the month," analysts at Thomson Reuters (Dusseldorf: TOC.DU - news) said in a daily research note.

* "However, the first days of April are expected colder compared to the previous forecast," the analysts said.

* Home heating accounts for around 40 percent of Britain's gas use, meaning temperature can have a big impact on demand.

* Another liquefied natural gas tanker is due to arrive in Britain this month, bringing the total to three.

* Winter 2018 contract up 0.46 at 53.41 p/therm.

* Day-ahead gas price at the Dutch TTF hub up 0.21 euro at 21.63 euros per megawatt-hour.

* Benchmark Dec-18 EU carbon contract up 0.26 euro at 11.81 euros per tonne.

* Thomson Reuters analyst view:http://emea1.apps.cp.extranet.thomsonreuters.biz/cms/?pageid=united-kingdom-gas (Reporting By Susanna Twidale; editing by Nina Chestney)