December natural gas gapped lower on Monday and remained under pressure all session. The gap opening was expected, but no one was certain of its direction until warmer-trending weekend forecasts shifted sentiment to the downside. Traders also said that more than adequate supply levels also weighed on prices.Bespoke Weather Services said, heading into Monday’s trading, both the American and European models had shifted warmer by several gas-weighted degree days (GWDD) compared to Friday’s outlook.