Citi's analyst thinks nat gas prices could quadruple if this winter is severe and cold.Okay.Let's focus on fundamentals instead.Inventory levels are at their lowest in the last 10 years. Last week the build was 46BCF. So where is this largest natural gas injection ever occurring? Regardless of the weather, nat gas prices will go up naturally. $CHK, Chesapeake Energy Corporation / H1 $UNG, United States Natural Gas Fund LP / H1 $UGAZ, VelocityShares 3X Long Natural Gas ETN linked to the S&P GSCI Natural Gas Index Excess Return / H1