* Demand remains below seasonal norm
* Another LNG cargo to arrive on May 30
LONDON, May 23 (Reuters) - British gas prices for immediate delivery eased on Friday morning as weak demand and healthy supplies of liquefied natural gas (LNG) offset less Norwegian pipeline gas imports.
Gas prices for delivery within the day were down by 0.15 pence to 45.65 pence a therm by 0815 GMT, while prices for delivery the next day were trading at 45.45 pence per therm, 0.05 pence up since their last close.
National Grid data showed that Britain's gas demand was only expected to be around 179 mcm on Friday, 8 percent below the seasonal norm, while supplies were forecasted at 177 mcm, leaving the system close to balanced.
Meteorologists said they expected average temperatures in Britain to rise above the seasonal norm of around 12 degrees Celsius on Friday, and continue rising steadily to 13-14 degrees towards the end of the month, after a small dip on Saturday.
Norwegian gas flows through the Langeled pipeline, Britain's main subsea gas import route, were at 7 mcm per day on Friday morning, just a tenth of its full capacity.
Imports from Norway were expected to remain low until next Thursday due to maintenance at Royal Dutch Shell's Ormen Lange field, the second biggest on the Norwegian continental shelf.
Lower deliveries from Norway were offset by LNG supplies from Qatar. Four LNG cargoes are arriving to South Hook between May 22 and 28, with daily gas sendouts estimated at 50 mcm.
"This is sufficient to counterbalance the impact of Norwegian maintenance and limit the level of storage withdrawals," said Oliver Sanderson, an analyst at Thomson Reuters Point Carbon.
Another LNG cargo from Qatar is expected to arrive to the South Hook terminal on May 30, the port's data showed. (Editing by William Hardy)