The within-day contract slipped 0.45 pence to 41.80 pence per therm by 0900 GMT.
The day-ahead contract edged 0.25 pence higher to 42.25 p/therm.
Britain's gas system was oversupplied by 8.5 million cubic metres (mcm), with demand forecast at 281.2 mcm and flows seen at 289.7 mcm/day, National Grid data showed
Flows from the UK Continental Shelf and from Norway along the Langeled pipeline increased total supplies by 21 mcm on Monday, according to Refinitiv Eikon data.
This offset a fall in supplies from LNG terminals, which are expected to reduce by 18 mcm to 61 mcm.
At least two LNG tankers are expected to discharge this week, with an extra tanker added to November deliveries after the Wilpride arrived over the weekend.
This brings Britain's LNG consumption to 1.659 million tonnes for the month, the highest monthly volumes since Refinitiv data began in 2013.
Britain's LNG imports are set to triple this year compared to 2018 due to a surge in LNG production globally.
Gas for power demand is seen falling by 10 mcm to 59 mcm with low wind power generation expected at 5.8 gigawatts (GW) out of a metred capacity of 15.3 GW.
Peak wind generation is seen rising on Tuesday to 8.6 GW.
Residential consumption, mainly used for heating, is expected to fall by 24 mcm to 180 mcm as temperature forecasts were increased by 2.2 degrees Celsius to 9.1 degrees
But temperature forecasts were revised sharply down for the weekend, by 4.7 degrees Celsius to 3.2 degrees with a concurrent increase in consumption by 42 mcm to 224 mcm.
Further out on the curve, most contracts also edged higher.
The December contract rose 0.70 pence to 43.25 p/therm.
The January contract rose 0.42 p to 45.05 p/therm.
The day-ahead gas price at the Dutch TTF hub jumped 0.75 euro to 16.40 euros per megawatt hour.
The benchmark Dec-19 EU carbon contract rose 0.05 euro to 24.63 euros per tone.