* System oversupplied by 12 mcm
* Langled flows rise to 49 mcm/d
May 13 (Reuters) - British prompt gas prices edged lower as an increase in imports from Norway left the gas system oversupplied, although the trend could potentially reverse due to a cooler weather outlook, traders said on Friday.
Gas for within-day delivery was 0.05 pence lower at 30.20 pence per therm at 0842 GMT from the previous settlement, while gas for weekend delivery was down 0.05 pence at 30.70 pence per therm.
"The prompt is down a bit due to oversupply, but stronger demand is expected over the weekend so that might change over the course of today," a UK gas trader said.
Maximum temperatures in the south of the country are expected to drop to 15 degrees Celsius on Saturday from 23 degrees on Friday, the UK Met Office said.
That leaves the UK gas system oversupplied by 12.1 mcm.
Norwegian gas flows through the Langeled pipeline, Britain's main subsea import route, rose to 49 mcm/day, up from 35 mcm delivered on Thursday.
"These flows should decline... otherwise there may be more acute oversupply," said Thomson Reuters gas analyst Oliver Sanderson.
UK-based consultancy Energy Aspects expects Norwegian gas production to rise by 4.5 billion cubic metres (bcm) year-on-year in the second quarter, but to fall by 1.7 bcm in the third quarter.
Gas for delivery in July fell by 1.45 pence to 29.65 pence per therm.
In the Netherlands' gas market, the day-ahead price at the TTF hub gained 0.22 euro to 12.95 euros per megawatt-hour.
In Europe's carbon market, the front-year EU Allowance price inched up by 0.02 euro to 5.83 euros per tonne. (Reporting by Nina Chestney; Editing by Nerijus Adomaitis)