Tropical Storm Laura has formed in the eastern Caribbean and forecasters say it could pose a hurricane threat to the U.S. Gulf Coast. And if that’s not enough, Tropical Storm Marco at the other end of the Caribbean may hit the U.S. western Gulf Coast after running across Mexico’s Yucatan Peninsula. The National Hurricane Center is forecasting both to make it into the Gulf of Mexico next week in what would be an almost simultaneous threat to the entire region. But there’s lots of uncertainty. First, Laura has to survive encounters with Puerto Rico, Hispanola and Cuba. Marco has to cross Yucatan.