* Gas flows below forecast demand by 6 mcm/day
* Supplies from South Hook LNG terminal seen up
* Rough withdrawal capacity reduced by 16 mcm/day
April 16 (Reuters) - Prompt natural gas prices in Britain eased on Thursday morning on expectations of increased supplies of liquefied natural gas (LNG) and higher temperatures next week.
Prices for delivery on Friday were down 0.40 pence at 46.90 pence per therm at 0845 GMT, while prices for within-day delivery were at 47 pence per therm, 0.05 pence lower from the previous session.
With supply flows forecast to be around 205.8 million cubic metres (mcm) on Thursday and demand expected to be around 211.8 mcm, the system was 6 mcm undersupplied, National Grid (LSE: NG.L - news) data showed.
"Despite the short system, prompt prices are trading lower, with the prospect of higher LNG send-outs improving the supply outlook," said Wingas analyst Andrew Crabtree.
Forecasts predicting temperatures above the seasonal norm next week were also weighing on prompt prices, he added.
LNG terminal South Hook is nominated to supply 24 mcm on Thursday, up from 20 mcm on Wednesday, with total LNG supplies rising to 36 mcm from 21 mcm, data from Thomson Reuters Point Carbon showed.
There were two new LNG cargoes expected to arrive to Britain from Qatar this week.
Britain's Rough natural gas storage facility will have its withdrawal capacity reduced by 16 mcm per day until 0559 local time on Friday due to a valve change, operator Centrica said.
Further along the curve, gas for delivery in May was 0.40 pence lower at 45.60 pence per therm.
London-based consultancy Energy Aspects said European gas demand might be higher this summer due to forecasts for warmer than normal weather, which would increase demand for cooling, on top of lower LNG prices and the need to refill storage sites.
Gas for delivery in Winter 15 was trading at 50.70 pence per therm, 0.10 pence down from the previous day.
In the Netherlands, the day-ahead gas price at the TTF hub was 0.25 euros lower at 22 euros per megawatt-hour (MWh).
The benchmark European Union carbon price dipped 4 euro cents to 6.85 euros a tonne on ICE Futures Europe. (Reporting by Nerijus Adomaitis; Editing by Nina Chestney and Mark Potter)