SAN PEDRO SULA, Honduras — Tropical Storm Sara formed Thursday in the Caribbean Sea and began lashing the sparsely-populated Caribbean coast of Honduras with heavy rain.

Sara was expected to cause life-threatening flash flooding and mudslides across portions of Central America, including Honduras, forecasters said.

The storm was about 85 miles northwest of the east coast border between Honduras and Nicaragua Thursday evening, the U.S. National Hurricane Center said. Sustained winds were maxing out at nearly 40 mph, with stronger gusts, as the storm moved west at about 10 mph, the agency said.

The storm was expected to stall and meander near the coast of Honduras through the weekend, according to the agency.

By Sunday Sara could strengthen slightly and approach the coast of Belize. Heavy rain also is forecast for Belize, El Salvador, eastern Guatemala and western Nicaragua.

Mexican authorities warned it could cause “intense rains” over the resort-studded Yucatan peninsula.

It was too soon to determine Thursday morning what conditions the system could bring next week to portions of the eastern Gulf of Mexico, including Florida, the Florida Keys, and Cuba, the hurricane center said.