UK GAS-Spot prices rise on supply outages and Norwegian cuts

* Norwegian imports decline; outages cut supply

* Gas system undersupplied by 19 mcm/day

May 6 (Reuters) - British prompt gas prices rose on Friday as supply outages and lower Norwegian imports tightened supplies.

Gas for within-day delivery rose by 0.40 pence per therm to 30.00 p/therm at 0917 GMT from the previous settlement, while gas for weekend delivery rose by 0.70 p to 29.70 p/therm.

Britain's gas market was undersupplied by 19 million cubic metres/day (mcm), with daily demand forecast at 202.1 mcm/day, according to National Grid (LSE: NG.L - news) data.

Gas demand slipped compared with levels earlier this week thanks to forecasters predicting warmer weather, but higher gas burn by power producers helped prevent steeper falls in demand.

Heavy withdrawals from stored reserves, particularly at Britain's biggest storage site Rough, were expected to balance the system later, analysts and traders said.

Rough was pumping out 23 mcm/day at a time of year when it would usually be rebuilding reserves used up in the winter.

One analyst said Rough needed to raise its current rate of output by 3 mcm to balance the system.

Norwegian imports via the Langeled pipeline continued to decline, running at 12 mcm/day from 13 mcm/day on Thursday and 40 mcm/day earlier this week.

"A continuation of lower imports from Norway together with unplanned outage further hampering supply are seeing prices across the prompt trade higher," said Marcel Boonaert, head of trading and portfolio at Wingas UK.

SSE (LSE: SSE.L - news) 's Aldbrough gas storage site is experiencing an outage until 1400 GMT, while a partial shutdown of Total (LSE: 524773.L - news) 's St Fergus terminal has cut 12 mcm/day of UK supply.

Further along the curve, the June contract rose by 0.52 pence to 29.17 pence per therm, while the Winter '16 contract was down 0.10 pence at 36.10 pence per therm.

In the Netherlands' gas market, the day-ahead price at the TTF hub gained 0.23 euro to 12.83 euros per megawatt-hour.

In Europe's carbon market, the front-year EU Allowance price fell 0.04 euro to 6.16 euros per tonne. (Reporting by Oleg Vukmanovic; editing by Nina Chestney)