Weather forecasting bobs up in discussion of oil rig’s grounding

On Dec. 21, the Kulluk oil rig — pulled by a tug — left the Aleutian Island port of Dutch Harbor for a long, slow journey south to Seattle.

Shell Oil officials have said forecasts indicated a two-week favorable weather window for the sea voyage. They say those forecasts did not predict the fierce Gulf of Alaska storms that on Dec. 27, severed a tow line, in a series of mishaps that Dec. 31 resulted in the Kulluk, amid seas of up to 40-feet, washing aground near Kodiak Island.

But as early as Dec. 21, the day of departure, one weather model did indicate the crossing might not be easy.

The Global Forecast System model, while not predicting wave heights, indicated that a significant low-pressure system — which could create stormy weather — would move into the seas off Kodiak. That model got sharper as the days progressed, according to Cliff Mass, a University of Washington professor of atmospheric sciences who reviewed the weather-model predictions. “It showed a serious low-pressure system, and it was coming into the northern Gulf of Alaska,” Mass said.

Andy Haner, a National Weather Service meteorologist in Seattle, said that multiple models are used to develop specific agency forecasts. But Global Forecast System Model, which is developed by the weather service through computer analysis, is an important tool, according to Haner.

“That is one of the top two or three models that we used to develop NWS forecasts,” Haner said

In planning the oil rig’s journey south, Curtis Smith, a Shell Alaska spokesman, said the oil company used ImpactWeather, a company that specializes in site-specific early-weather forecasting. Smith also noted that longer-range National Weather Service forecasts for the Gulf of Alaska “appeared to track with us.”

“Obviously, weather, especially in the Gulf of Alaska, is dynamic and unpredictable but you use the best information you have,” Smith said in a written statement.

A National Weather Service meteorologist in Anchorage on Friday was unable to provide copies of the long-range marine forecasts made for the Gulf of Alaska in late December.

The Kulluk was one of two oil rigs Shell used this summer as part of an offshore Arctic exploration effort. The Monday evening grounding could be a blow for the company’s plans to resume drilling next summer.

Since drifting aground Monday near Kodiak, the Kulluk oil rig has sustained damage to generators, and seawater has penetrated some inside areas, according to reports from a Unified Command of state, federal and industry officials involved in the salvage effort. But the rig remains stable, and the latest reports do not indicate any fuel links.

On Friday, more salvage crews boarded the rig to assess damage, and 14 vessels were mobilized to assist in the response. Crews have made “significant progress,” according to a statement released by the Unified Command, which did not lay out any timelines for the salvage effort.

Shell officials have said the Kulluk was being towed south to undergo maintenance in Seattle. Though Dutch Harbor and the town of Unalaska have maritime-support services, they are often busy through the winter servicing fishing fleets.

Smith said the decision was made to move the vessel to Seattle after a post-drilling inspection concluded the maintenance program “was not achievable in Dutch Habor.”

In December, Shell also was aware the Kulluk would be subject to Alaska state taxes if moored in state waters on Jan. 1.

In Dec. 27 e-mails to Jim Paulin, a reporter for the Bristol Bay Times and Dutch Harbor Fisherman, Smith said “it was fair to say” one factor influencing the timing of the Kulluk’s departure was “the current tax structure,” and indicated the tax would cost Shell multiple millions of dollars.

In a statement on Friday, Smith said that “while we are aware of the tax environment, wherever we operate, operational decisions are ultimately governed by safety.”