BANGALORE (Reuters) - The first major Gulf of Mexico storm of the year is brewing over the northwestern Caribbean Sea, with an 80 percent chance of becoming a tropical cyclone as it heads northwest to the Texas coast, and posing a threat to energy facilities in the area.
The U.S. National Hurricane Center said the tropical wave, moving over the Yucatan Channel at 15 miles per hour (24 kmph), may develop into a tropical depression later on Wednesday.
Computer weather models project the system will hit somewhere between northeast Mexico and the Texas coast over the next few days. Projected tracks have shifted more northeastward to the coast of Texas over the last 24 hours.
About one-quarter of U.S. oil production and some 10 percent of natural gas output is vulnerable to this storm, to be named Don if it strengthens.
"A move to the North or Northwest could prompt precautionary shut-ins of offshore production facilities, depending on its intensity, although it will need to strengthen rapidly to pose any threat to facilities," JP Morgan analyst Lawrence Eagles said in a note.
Shell said "early preparations" were under way to secure operations at its Perdido oil and gas platform -- which can produce up to 100,000 barrels of oil per day -- and the nearby Noble Danny Adkins drilling rig.
"No significant evacuations right now, but we're monitoring the storm," a spokeswoman said.
BP spokesman Daren Beaudo also said the company was monitoring the system.
Refiners with facilities in the region were being vigilant.
Marathon Petroleum Corp said it was monitoring the storm on behalf of its 76,000-bpd refinery in Texas City, while LyondellBasell was watching the weather on behalf of its 280,700-bpd refinery in Houston.
"No significant action is required at this time other than to continue to monitor the weather reports because basic preparation steps were completed in June," LyondellBasell spokesman David Harpole said.
Mexico's state oil monopoly Pemex said it had no immediate plan to evacuate platforms in the southern Gulf, halt production or close exporting ports in the area.
"Anyone who has interests in the northeastern Yucatan peninsula, as well as the central and western Gulf of Mexico, should monitor the progress of this system," the NHC said.
(Reporting by Antonita Devotta, Ratul Ray Chaudhuri, Soma Das, Koustav Samanta and Naveen Arul in Bangalore, Kristen Hays in Houston and Mica Rosenberg in Mexico City; Editing by Dale Hudson)