Natural gas prices finish a slight 0.4% lower at $3.069/mmBtu, but end with a 5.4% weekly increase -- the fourth straight weekly rise for the commodity. The rising trend for natural gas this week was largely due to a brutally-cold winter storm that took Texas by surprise and forced some 20% of US gas production offline. But gas prices have begun to retreat the past two sessions, partly on concerns that LNG exports are also being hurt by the winter storms, but also on worries that such a cold February might lead to the sudden arrival of an early and warm spring that could hurt demand.