There are “no visible signs” that a Royal Dutch Shell oil drilling barge that ran aground last week off southern Alaska has leaked fuel into the surrounding waters, though bad weather is preventing it from being towed away, officials said Sunday.

“The Kulluk continues to remain stable and upright,” states a Sunday update on the response effort’s official website. The effort consists of a “unified command” including Shell, the U.S. Coast Guard, Alaska’s state environmental conservation department, Noble Drilling and the borough of Kodiak Island.

But inclement weather is hampering efforts to connect a tow line to the Kulluk rig so it can be moved about 30 miles north to Kiliuda Bay so that authorities can make a more thorough assessment.

According to the National Weather Service, a mix of rain and snow, sustained winds of up to 20 mph and temperatures in the 20s and 30s are forecast from Sunday afternoon through Monday night for Old Harbor, one of the communities nearest the stranded rig.

Authorities have not set a time when the Kulluk — a double-hulled steel vessel with a helicopter landing pad and tower in the middle designed for drilling in Arctic waters — will be towed. A “recovery team” was monitoring the situation from onboard the rig, according to the unified command update.

“The very nature of the recovery operations and the difficult weather conditions must be managed without compromising safety,” said U.S. Coast Guard Capt. Paul Mehler III in comments made Saturday afternoon and posted online Sunday.

“Our time line is still difficult to nail down, but we are committed to seeing this response through to a safe conclusion.”

The 266-foot diameter Kulluk was being towed back to its winter home in Seattle when it ran into a severe storm December 28 off the Alaskan coast. The Coast Guard evacuated the rig’s 18-man crew the next day, and it drifted for 10 hours the next day after the tug that was towing it lost power.

On Monday night — New Year’s Eve — tug crews had to cut the rig loose during a storm that whipped up 24-foot waves. That led to its grounding off uninhabited Sitkalidak Island, about 200 miles south of Anchorage, in an area where water is 32 to 48 feet deep.

Most of the nearby shore is owned by a native Alaskan corporation on adjacent Kodiak Island, according to Steven Russell, an official with Alaska’s Department of Environmental Conservation. State officials are working with residents to assess any environmental impact caused by the grounding.

The Sunday update noted no visible signs of leaks thus far. Sean Churchfield, the incident commander and operations manager for Shell Alaska, said the previous day the rig’s fuel tanks appear intact, and naval architects report the vessel is sound and fit to tow.

“Currently, the Kulluk recovery operation does not pose any environmental threat that would preclude (the Tanner Crab Fishery and others) from opening,” said Russell.

As much as 150,000 gallons of ultra low sulfur diesel and approximately 12,000 gallons of other petroleum products are on board the Kulluk.

All the fuel was to power equipment and did not come from drilling operations. The rig had been working in the Beaufort Sea, off Alaska’s North Slope, which is on the other side of the vast state from where it now rests.

Shell’s Arctic exploration plans caused widespread concern among environmentalists and were held up after BP’s 2010 Deepwater Horizon disaster in the Gulf of Mexico.

Shell says it’s working at far less depth and lower pressures than the BP well that erupted off Louisiana, killing 11 men aboard and unleashing an undersea gusher that took three months to cap.

The U.S. Geological Survey estimates more than 90 billion barrels of oil and nearly 1,700 trillion cubic feet of natural gas may be recoverable by drilling in the North Slope. And the shrinking of the region’s sea ice — which hit record lows in 2012 — has created new opportunities for energy exploration in the region.

Climate researchers say that a decrease in sea ice is a symptom of a warming climate, caused largely by the combustion of carbon-rich fossil fuels. The science is politically controversial but generally accepted as fact by most scientists.