UK GAS-Prices rise on undersupply, lower wind output

* System undersupplied by 24 mcm

* Wind output forecasts lower for Thursday

LONDON, June 3 (Reuters) - British prompt gas prices rose on Wednesday due to undersupply and lower wind output forecasts.

Gas for day-ahead delivery was up 0.35 pence at 44.50 pence per therm at 0749 GMT.

National Grid (LSE: NG.L - news) data showed supply was forecast at 181 million cubic metres (mcm) on Wednesday, while demand was expected at nearly 205 mcm, meaning the system was undersupplied by 24 mcm.

Flows from Norway through the Langeled pipeline briefly dropped to zero on Tuesday due to an unplanned outage at the Troll field.

That outage is now over and flows should pick up to around 11 mcm on Wednesday and towards 15 mcm on Thursday, but will drop back to the 10-12 mcm level when Zeepipe returns from maintenance on June 8, said Thomson Reuters Point Carbon analyst Oliver Sanderson.

Zeepipe transports gas from the North Sea to a receiving terminal at Zeebrugge in Belgium.

On the demand side, utilities' gas demand has risen due to lower wind output forecasts, traders said.

Peak wind generation is forecast at 4,882 megawatts (MW) on Wednesday but much lower on Thursday, at 1,658 MW, according to National Grid data.

Further along the curve, gas for delivery in July was up 0.30 pence at 42.55 pence per therm.

In the Netherlands, day-ahead gas at the TTF hub was up 0.10 euros at 20.45 euros per megawatt-hour.

The benchmark European Union carbon price was down 0.02 euros at 7.46 euros a tonne on ICE Futures Europe. (Reporting by Nina Chestney; Editing by Pravin Char)