A tropical storm in the Gulf of Mexico strengthened into the season’s first hurricane late Tuesday, the U.S. National Hurricane Centre said.

Hurricane Alex, a category 1 storm with sustained winds of 120 kilometres per hour, was expected to make landfall in northern Mexico or southern Texas late Wednesday, forecasters said.

Heavy rainfall was expected, and the hurricane centre warned of possible life-threatening flash floods and mudslides in mountainous areas.

Though the centre of Alex remains far from the spill that has for months been spewing crude oil into the water off Louisiana, it was already causing massive waves that will delay by about a week an operation to collect most of the oil gushing from the ruptured well at the bottom of the ocean, oil company BP plc said earlier Tuesday.

Other containment measures including the drilling of relief wells and skimming on the surface will also likely have to be temporarily shut down in coming days as vessels are forced to return to shore.

The oil spill caused by Deepwater Horizon oil rig’s explosion on April 20 has dealt a heavy economic and ecological toll on the four southern U.S. states along the Gulf Coast.

The Atlantic season’s first storm was the earliest hurricane since 1995.

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