Robust flows of natural gas southward from Canada into the Lower 48 in November are bolstering already stout U.S. supplies, helping to keep next-day cash prices in check relative to last year, analysts say.

“For most of the month, imports have run more than 1 Bcf/d higher than last year, with strength most evident in flows to the West and Upper Midwest,” Mobius Risk Group analysts said. “This source of incremental supply is adding to reported all-time domestic production, and challenging market bulls who have seen a multi-month period of tight weather adjusted inventory data.”

U.S. production over a recent seven-day run averaged more than 105 Bcf/d – a record and nearly 4 Bcf/d above year earlier levels, according to an analysis issued Friday by Wood Mackenzie Canadian...