The National Hurricane Center in Miami said Alma had maximum sustained winds near 65 mph (100 kph) and was expected to strengthen to a hurricane before plowing into the northwest corner of Nicaragua late Thursday.

The storm was located about 50 miles (80 kilometers) southwest of Managua and was moving north at 7 mph (11 kph).

Authorities issued hurricane warnings for the coasts of Nicaragua and Honduras. Heavy rains caused flooding in Managua.

Costa Rican authorities evacuated low-lying areas and set up more than 160 storm shelters after Alma dumped rain over the country for 24 hours. A few highways were blocked by landslides.

The hurricane center predicted the storm would plow through the southern border region of El Salvador and Honduras early Friday.

Forecasters warn that Alma could dump as much as 20 inches (50 centimeters) of rain in places.

The eastern Pacific hurricane season began May 15.