August natural gas is set to open 4 cents higher Thursday morning at $2.82 as weather forecasts prove riskier and traders anticipate the release of storage data showing increases less than historical averages. Overnight oil markets rose.

Overnight weather models turned more uncertain with mixed patterns east and west. "Hopes of a better model consensus and clearer forecast picture going into the three-day holiday weekend have been dashed as the models show a muddier story with increased uncertainties," said forecaster Commodity Weather Group in its morning report. "On the whole, today's forecast sees cooler changes East and South in the one- to five-day, warmer to hotter changes Midwest to East (cooler West) for the six-10 day, and the 11-15 day is slightly warmer to hotter East Coast, while cooler again West.

"The situation appears too active for a major heat wave pattern look (still rainy risks), but at the same time, upper-level heights are too warm for significant cooling. What we get is this muddled look with lots of near-normal on the maps," said Matt Rogers, president of the firm.

Analysts see elevated power generation requirements as prompting a below-normal storage build. The 10:30 a.m. EDT report by the Energy Information Administration is expected to see injections generally in the vicinity of 70 Bcf, less than last year's 102 Bcf injection and the five-year pace of 75 Bcf.

"Power burn demand drove the entirety of the increased demand compared to the previous week, and averaged 32.3 Bcf/d during the week, which marks the highest that power burn demand has averaged during a given week since 2012," said Bentek Energy. "Power demand peaked as high as 34.6 Bcf/d during the week, which is the strongest burn levels have peaked all year."

Other estimates include Ritterbusch and Associates at 77 Bcf; a Reuters survey of 24 traders and analysts revealed a sample mean of 70 Bcf with a range of 60 Bcf to 77 Bcf. Bentek Energy calculates a 70 Bcf increase.

As far as a market reaction, "I'm thinking anything above a 70 Bcf build might give the market a push to the downside, and a number in the low 60s would bump this thing up pretty well," said a New York floor trader.

In overnight Globex trading August crude oil gained 70 cents to $57.03/bbl and August RBOB added 3 cents to $2.0360/gal.