UK GAS-Prices slip on ample supply, mild weather

* System long 21 mcm - National Grid (LSE: NG.L - news)

* Langeled flows at around 59 mcm/day

LONDON, Jan 29 (Reuters) - British gas prices fell on Friday as strong exports from Norway meant there was ample supply to meet slack demand, with milder weather curbing gas needs for heating.

Gas for immediate delivery traded down 0.85 pence, or 2.7 percent, at 30.25 pence per therm as at 1036 GMT.

Britain's gas system was oversupplied by 21 million cubic metres (mcm), with demand forecast at 261 mcm and supply at 282 mcm, according to National Grid data.

Norway's Langeled pipeline flows, the major import vein for Britain, were around 59 mcm on Friday, up from around 52 mcm earlier this week.

The Met Office forecasts temperatures of around 10 to 13 degrees Celsius, above seasonal norms, with strong winds across the north of Britain.

Wind power output was expected to peak at 6,890 megawatts on Friday.

"Milder conditions expected for today have seen LDZ (local distributions zones) consumption forecasts soften by around 15 mcm from yesterday, with high wind output seeing marginally lower offtake from CCGT (combined cycle gas turbine) generation," said Marcel Boonaert, head of trading and portfolio at Wingas UK.

Further along the curve, gas for March was trading down 1.03 pence or 3.2 percent at 30.65 pence per therm.

In the Netherlands, the day-ahead gas price at the TTF hub fell 0.65 euro to 13.10 euros per megawatt-hour, while in the European carbon market, front-year allowances eased by 0.01 euro to 6.08 euros a tonne. (Reporting by Sarah McFarlane; Editing by David Evans)