The February Nymex natural gas futures contract ended on a positive note Tuesday, recovering from early losses as long-range forecasts hinted at more cold arriving after a milder break next week. In the spot market, Midwest prices surged for a second straight day as forecasters were looking for the most extreme temperatures from this week’s polar cold front to hit the region Wednesday; theNGISpot GasNational Avg.added 77.5 cents to $4.400/MMBtu.