UK GAS-Prompt prices rise as cool weather boosts demand

* Demand up about 10 pct on seasonal norm

* Flows from Norway reduced by Troll outage

LONDON, April 27 (Reuters) - Prompt natural gas prices in Britain rose on Monday morning as forecasts for cooler weather led to higher than usual demand.

Prices for within-day delivery were at 46.15 at pence per therm at 0840 GMT, up 1.35 pence since their last settlement. Prices for delivery on Tuesday were up 0.6 pence at 46.15 pence per therm.

With supply flows at about 219.3 million cubic metres (mcm) per day on Monday and demand expected to be about 223.2 mcm, the system was 3.9 mcm undersupplied, National Grid (LSE: NG.L - news) data showed.

Monday's demand was about 10 percent above the seasonal norm of 202 mcm, the data showed.

"This week looks as though it will be pretty unsettled and quite cold at times," a meteorologist at Britain's Met Office said in a webcast on Monday, adding that temperatures would average around 8-11 degrees during the day.

Gas flows from Norway were still restricted by outage at the country's largest gas field, Troll, which started on April 10.

Flows from Norway to Britain via the Langeled pipeline were about 17 mcm per day on Monday morning, National Grid data showed.

Langeled is Britain's main sub-sea gas import pipeline and has maximum capacity of about 70 mcm a day.

The outage at Troll is due to end on Tuesday.

Further along the curve, gas for May delivery was 0.3 pence higher at 44.7 pence per therm.

In the Netherlands, the day-ahead gas price at the TTF hub was 0.05 euros lower at 21.70 euros per megawatt-hour (MWh).

The benchmark European Union carbon price edged 0.05 euros higher to 7.37 euros a tonne on ICE Futures Europe. (Reporting By Susanna Twidale; Editing by David Goodman)