Tropical Storm Isaac, downgraded from Category 1 hurricane status, continues its slow trek across Louisiana, dumping large amounts of rain, producing life-threatening hazards from storm surge and inland flooding, and continuing to impact offshore rigs and onshore refining and petrochemical facilities, says IHS (NYSE:IHS), the leading global source of information and analytics.

50 U.S. Gulf of Mexico (GOM) offshore drilling rigs in federal waters (nearly 66 percent of the GOM total) and 505 production platforms in federal waters (nearly 85 percent of the GOM total) in the storm's path have been shut-in and evacuated, as compared to 49 rigs and 503 platforms shut-in yesterday. Numerous onshore chemical and refining facilities also shut down operations, which is impacting refining and petrochemical production, says a special Hurricane Isaac report from IHS Chemical.

As of 4 p.m. CST, Isaac was maintaining maximum sustained winds of 70 miles-per-hour. The storm center was located at 30 degrees north and 91.1 degrees west, roughly 60 miles west of New Orleans and 35 miles south of Baton Rouge, La. The storm is continuing to track northwest, but has further slowed to 6 miles-per-hour, increasing the danger of flash-flooding from higher rainfall amounts.

Plaquemines Parish was subject to a 12-foot storm surge and many homes have been inundated with water. Generally, slower moving storms, such as Isaac, generate a larger storm surge and produce higher rainfall amounts. Currently, half a million New Orleans residents are without power, although the levees rebuilt after Hurricane Katrina are holding up.

According to statistics reported by the U.S. Bureau of Safety and Environmental Enforcement (BSEE), more than 1.3 million barrels of oil production are now shut-in in U.S. federal waters, and more than 3.2 billion cubic feet of gas-per-day in federal waters, has been shut-in due to Tropical Storm Isaac.