May 10, 2010

Oil slick may threaten more of Louisiana coastline

Winds from the southeast threaten to push the oil slick towards more of the Louisiana coastline during the next few days.

Concerns of hurricanes and drift will remain for the weeks and months ahead.

Winds above the sunken oil well were generally blowing from the east at 10 to 18 mph Sunday afternoon. Wave heights were averaging around 4 feet.

The winds and local currents have caused the slick to stretch westward.
Winds have now become southeasterly at 10 to 18 mph and will continue to blow in this fashion into Thursday with locally higher gusts.

The winds into Thursday could act to push the oil slick northwestward, either towards or onto a large part of the Louisiana coastline.

The coastline at greatest risk for the oil slick to push onshore lies from Atchafalaya Bay to Louisiana's southeasternmost point. Places northwest of Breton Sound will also be threatened.

Waves will be around 3 feet on Monday, but will increase to 5 to 7 feet Wednesday into Thursday.

Increasing wave heights into Wednesday may work to break up parts of the oil slick, but could progressively lower the efficiency and stability of boom systems.

Meanwhile, approximately 5,000 feet down, there is no significant wave action.

Even during a hurricane, the weather at the bottom remains relatively calm, aside from steady deep water currents.

The onshore winds and building waves the next few days could also cause some stability challenges for surface vessels and containment/cleanup operations.

A grim hurricane forecast hurricane expert Joe Bastardi remains concerned about the possibility of a June hurricane in the Gulf of Mexico this year.

Typically in June, hurricanes form in the western Caribbean and drift northward toward regions such as the Gulf of Mexico.

While the potential effects of a hurricane on the oil slick are indeed a wild card, there are some scenarios to ponder.

Depending on the strength and track of tropical storms, periodic rough seas could be a serious problem for containment operations and may halt the process until the storms pass.

Strong winds could steer part of the existing surface oil slick toward the northern Gulf Coast, or elsewhere. High winds from a hurricane could also cause some oil to become airborne in blowing spray, while a storm surge could carry contaminants inland.

On the other hand, to some extent rough seas and heavy rain tend to work toward breaking up an oil slick.

Unpredictable Long-term drift

While the factor of winds, waves and storms makes for a tremendous forecast challenge as to where the oil slick will end up, ocean currents take the problem to a whole new level.

The Loop Current, located in the southeastern Gulf of Mexico, is a concern, as it links to the Gulf Stream, which carries warm water northward along the Atlantic Seaboard.

In theory, if the oil slick were to get caught in the Loop Current, it could be transported to the Gulf Stream around Florida waters, then up part of the East Coast, potentially impacting wildlife and shoreline communities along the way.

On one hand, prevailing winds over the open waters of the Gulf of Mexico this time of year are from the south. Since the slick is still over 100 miles away from the main circulation of the Loop Current in the southeastern Gulf, it would appear not to be an immediate concern.

However, small local spirals, known as eddies, often break off of the Loop Current and could cause the slick to wander and spread just about anywhere. The Loop Current itself often changes shape and location to some extent, adding more uncertainty to the mix.

Local currents along the shoreline may protect some communities and could bring the slick onshore in others. However, winds and tides can cause these local currents to shift by the hour.

One thing is for sure, the longer the leak goes unchecked, the greater the chance of the slick spreading to areas other than just the Louisiana shoreline.

Story by Expert Senior Meteorologist Alex Sosnowski with contributions from Senior Meteorologist Kristina Pydynowski

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