* Winter gas demand unchanged at 55.7 billion cubic meters (Adds gas demand-supply outlooks, detail)LONDON, Oct 11 (Reuters) - UK gas and power network operator National Grid expects colder-than-normal temperatures in Britain and Europe this winter, while electricity demand and power plant availability are forecast to be 4 percent lower this winter.In its Winter Outlook 2011/12 forecast published on Tuesday, it saw a 20 percent to 60 percent probability of below normal temperatures and said power producers are expected to "strongly favour" cheaper coal instead of gas for electricity generation.The network manager revised down its power generation availability for this winter to 61.3 Gigawatts versus 63.8 GW in earlier forecasts, while power demand was also revised down to 55.8 GW compared with 58.1 GW earlier - a reduction of 4 percent in both cases.National Grid also said it expected Germany's decision to phase out 8.3 GW of nuclear capacity to increase gas exports from Britain to Belgium."Germany's recent decision to close 8.3 GW of nuclear plant immediately and put in place a phased closure of all nuclear plant by 2022 is expected to have impacts during this winter," the network operator said.National Grid also said 2 GW of power generation capacity was mothballed this winter, but expected some of this generation could become available if electricity prices rise.Peak winter demand for gas was left unchanged at 474 million cubic meters/day chiefly because coal is expected to sideline gas as the leading power plant fuel.But the network operator said factors such as limited running time of coal plants under the EU's Large Combustion Plant Directive (LCPD) will influence generators' fuel choice.Total demand for gas this winter was left unchanged at 55.7 billion cubic meters. Grid added that exports to mainland Europe via the Britain-Belgium gas link are subject to "considerable uncertainty," potentially driving demand higher if exports run at maximum capacity during winter.Turning to supplies of gas, Grid says reduced output from the UK Continental Shelf will be offset by modest increases in liquefied natural gas (LNG) deliveries from Qatar.Falling indigenous production will be further cushioned by stockpiles of gas held in storage especially as new facilities are opened over the next few months, boosting stocks to all-time highs, Grid said.
