The extraordinary tumult in the physical natural gas market rippled through the forward curves  during the trading week ended Wednesday as hubs throughout the country posted sizable week/week gains in both fixed and basis prices.

Prompt-month fixed prices in NGI’s Forward Look rallied by the double digits from coast to coast for the Feb. 11-17 period, while fixed prices for April also strengthened across the board, albeit to a lesser degree.

The higher forward prices coincided with a week of unprecedented conditions in the spot market, where day-ahead prices at numerous hubs surged into the hundreds of dollars — and in some cases over $1,000 — as a deep freeze in the Gulf Coast and Midcontinent disrupted operations for producers, pipelines, power generators and...