* Gas system oversupplied by 14 mcm
Feb 9 (Reuters) - British within-day gas prices were little changed on Tuesday as rising supply from LNG terminals left the system oversupplied, while day-ahead prices firmed on a colder weather outlook.
Gas for immediate delivery inched up 0.05 pence to 29.50 pence per therm, while day-ahead contract gained 0.35 pence or 1.2 percent to 29.70 pence/therm.
Britain's gas system was oversupplied by 14 million cubic metres (mcm), with demand forecast at 314 mcm, above the seasonal norm of 288 mcm, while supply was 328 mcm, National Grid data showed.
Flows into the St Fergus Shell terminal were restarted on Monday evening after maintenance at the Norwegian entry to the SEGAL pipeline ended.
"LNG sendout is a key driver today," they said.
Deliveries from Britain's LNG terminals are nominated at 55 mcm for Tuesday, indicating more tanker arrivals in the future, after a new cargo to South Hook was confirmed for Feb. 16.
Meanwhile, day-ahead prices were lifted by expectations for demand to rise, as temperatures are predicted to drop below seasonal norms, traders said.
Further along the curve, gas for March was trading up 0.45 pence or 1.6 percent at 29.35 pence per therm.
Contract for gas delivery next-season, was at 28.10 pence/therm, 0.51 pence or 1.9 percent up.
In the Netherlands, the day-ahead gas price at the TTF hub rose 0.2 euro/MWh or 1.6 percent, at 12.45 euro/MWh.
In the European carbon market, front-year allowances eased 0.02 euro to 5.23 euro a tonne.
(Reporting by Nerijus Adomaitis; editing by Jason Neely)