* Demand 11 pct below norms on temperature spike * Day-ahead gas hits 16-day high ahead of cooling * LNG terminals pump 35 pct less gas London, March 15 (Reuters) - British spot gas prices slipped on Thursday morning as unseasonably warm weather dented demand and offset a scheduled drop in flows from Total's St Fergus terminal, while curve contracts headed lower after recent gains. Gas delivered on Thursday dropped 0.15 pence to 59.85 pence per therm on the back of unexpectedly mild weather, with temperatures rising to 20 degrees Celsius by mid-afternoon and forcing demand 11 percent below average levels. The day-ahead contract however climbed to 59.85 pence per therm, a 16-day high, ahead of cooler temperatures, higher demand and ongoing supply disruptions from North Sea gas fields projected to tighten the network on Friday. Output from Total's St Fergus gas terminal will drop by 12 million cubic meters on Thursday and Friday for a period of 12-18 hours each day, due to maintenance, raising pressure on an already tight supply-demand balance, analysts said. "Possible need for storage withdrawals may add an upward price pressure on the DA contract," analysts from Point Carbon said. Liquefied natural gas (LNG) terminals pumped 35 percent less gas into the network at 27 mcm/day on Thursday versus Wednesday, National Grid data showed. Norway exported slightly less to the UK this morning, whereas sub-sea flows from Britain to Belgium were unchanged at 19 mcm/day. A further 8 mcm will be injected into storage sites during the day, adding to supply tightness. The benchmark summer 2012 gas contract drifted 0.15 pence lower to 60 pence on the day, seeking direction in the absence of clear signals from crude oil markets. In the power market, day-ahead baseload for 24-hour delivery edged 10 pence lower to 46.40 pounds per megawatt hour (MWh). (Reporting by Oleg Vukmanovic)

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