Only three hurricanes in U.S. recorded history have reached the monstrous Category Five classification (winds greater than 155 mph). Dennis was making a strong bid to become the fourth as it took aim on the Eastern Gulf of Mexico (GOM) on Friday, packing 150 mph winds. It made landfall along the south-central coast of Cuba Friday afternoon and was expected to enter the southeastern Gulf that night.

Producers scrambled to batten down the hatches in the eastern Gulf by evacuating workers from platforms and drilling rigs and shutting in production as necessary. Pipelines with offshore segments or connections in the area were posting bulletin board warnings of expected supply losses as the day wore on and instructing shippers on the proper response.

Based on reports from 19 companies as of 11:30 a.m. CDT Friday, Minerals Management Service (MMS) said 1,041.48 MMcf/d of gas and 220,326 bbl/d of oil had been shut in because of Dennis’ approach. A total of 81 platforms and 35 drilling rigs had been evacuated, MMS said. Because shut-in operations were proceeding throughout the day, supply losses were expected to rise sharply over the weekend.

MMS announced that it may close its Gulf of Mexico Regional Office in New Orleans on Monday because of Dennis. As a standard practice, MMS took steps to activate its Continuity of Operations Plan, which opens a temporary office in Houston when the New Orleans office faces a potential closure. A small team traveled to Houston Friday to open the temporary office. The agency said it would continue its normal daily release of shut-in and evacuation statistics on Monday regardless of which office is open.

The National Hurricane Center (NHC) said data from reconnaissance aircraft indicated that Dennis’s maximum sustained winds were nearly 150 mph, putting it in Category Four on the Saffir-Simpson scale. Some weakening was likely as Dennis moves over Cuba, but NHC expected it to remain a major hurricane as it emerged over the Straits of Florida and the southeastern GOM Friday night.

Dennis may drop “a category or two, maybe lose 25-30 mph” of wind velocity crossing Cuba, but “we expect it will quickly pick up again,” meteorologist Chris Hennon in the NHC Miami office said Friday. The NHC forecasters expected to see waves of 20-50 feet developing in the GOM for “this type of storm.” He said the waters where the hurricane was forming were a couple degrees above normal, which contributed to its quick development. And waters in the Gulf of Mexico at this point are about a degree Celsius above normal, which can be “fairly significant” in growing a storm.

In a Friday morning discussion of the storm’s immediate future, the Weather 2000 consulting firm had sobering news for those who think that oil and gas facilities west of the eastern GOM were safe from Dennis’ wrath. The consulting firm said that the hurricane might slightly change direction as it crosses western Cuba. “We continue to believe that the very real potential for Dennis to approach locations West of Pensacola, Florida, is not being emphasized enough. While the southern Texas Gulf Coast and southern Florida can perhaps both be statistically eliminated as final U.S. landfall locations for Dennis at this juncture, all others on the Gulf Coast still need to maintain a vigilant watch of Dennis’ progress.”

The NHC projections as of Friday afternoon had Dennis moving ashore near the Florida Panhandle/Alabama border at about 2 a.m. Monday morning.

Transco and Gulfstream expected to lose 200-300 MMcf/d each in supplies Friday, a spokesman said, with volumes increasing throughout the weekend as Dennis approached. Most of the losses were likely to occur in the Mobile Bay area, he added.

Trunkline and Sea Robin were both in good shape with no production losses yet, although it’s possible that some might turn up later, a spokesman said. Affiliate Florida Gas Transmission was seeing some reductions from offshore, but replacing a lot of that with onshore supplies and storage, he said.

A spokeswoman reported that Texas Eastern was experiencing supply losses that she was unable to quantify, but it was having no impact on deliveries as of midday.

Shell was shutting down production from its Mars, Ursa, Ram Powell, Main Pass 252 and Cognac facilities. It planned to evacuate about 860 workers from offshore facilities by late Friday. By early Saturday, Chevron plans to have all of its workers in the Central and Eastern Gulf evacuated.

Kerr-McGee began pulling workers out on Thursday, and continued Friday to evacuate personnel from the Neptune production platform, as well as the Main Pass and Breton Sound areas in the eastern Gulf. It was halting all drilling operations. Anadarko Petroleum said it has pulled out all nonessential personnel, and will shut down its Marco Polo platform by Friday night.

ExxonMobil evacuated 80 workers, but none of its production was affected as of early afternoon Friday, a spokesman said. Shell reportedly was shutting in 730 MMcf/d, while Kerr-McGee was said to be shutting in about 31,000 boe/d.

At 2 p.m. EDT Friday the center of Dennis was about 125 miles southeast of Havana, Cuba and about 190 miles south-southeast of Key West, FL. It was moving northwestward at nearly 17 mph. Because of the approach to land, maximum sustained winds had diminished slightly from earlier in the day to 145 mph. NHC called Dennis the strongest Atlantic hurricane to form so early in the season since records started being kept in 1851.

The federal agency said only three hurricanes have acquired Category Five status since such records began to get kept: an unnamed one that struck the Florida Keys in 1935 (before tropical storms and hurricanes started being named; Camille in 1969, which targeted Mississippi, southeastern Louisiana and Virginia; and Andrew in 1992, which wreaked its havoc on southeastern Florida and southeastern Louisiana.

Friday marked the second time in less than a week that a storm disrupted offshore exploration and production operations. Traders returned from their July 4 holiday weekend to find Tropical Storm Cindy on the verge of invading the production area on a track through New Orleans. However, Cindy came and went through the Central Gulf about as rapidly as Tropical Storm Arlene did last month, making its impact on production fleeting and relatively light.

No reports of any significant damage from Cindy were circulating, other than power outages that shut down several refineries in southeastern Louisiana. Cumulative Cindy-related losses of gas production from Tuesday through Thursday came to 1.683 Bcf, or 0.046% of the Gulf’s normal annual output of 3.65 Tcf, MMS said.

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