MANAGUA, Nicaragua -- Newly formed Tropical Storm Nate was blamed Thursday for at least 22 deaths across Central America as it dumped rain across the region on a path that would carry it toward a potential landfall on the U.S. Gulf Coast as a hurricane over the weekend. Louisiana officials ordered some people there to evacuate.

The U.S. National Hurricane Center said the storm could cause dangerous flooding by dumping as much as 15 to 20 inches (38 to 50 centimetres) of rain on Nicaragua, with higher accumulations in a few places.

It had maximum sustained winds of 40 mph (65 kph) at midday Thursday and was likely to strengthen over the northwestern Caribbean Sea Thursday night and Friday before a possible strike on the Cancun region at the tip of Mexico's Yucatan Peninsula.

In Nicaragua, Nate's arrival followed two weeks of near-constant rain that had left the ground saturated and rivers swollen. Authorities placed the whole country on alert and warned of flooding and landslides.

Nicaragua's vice-president and spokeswoman, Rosario Murillo, said that at least 15 people had died in that country due to the storm. She didn't give details on all the deaths, but said two women and a man who worked for the Health Ministry were swept away by a flooded canal in the central municipality of Juigalpa.

The government closed schools nationwide.

Costa Rica's Judicial Investigation Organism blamed seven deaths in that country on the storm and said 15 people were missing. Flooding drove 5,000 residents into emergency shelters.

In Louisiana, officials ordered the evacuation of part of coastal St. Bernard Parish east of New Orleans ahead of the storm. Earlier Thursday, a voluntary evacuation was called in the barrier island town of Grand Isle south of New Orleans.

New Orleans officials outlined steps to bolster the city's pump and drainage system. Weaknesses in that system were revealed during summer flash floods.

The storm was centred about 50 miles (80 kilometres) northwest of Puerto Cabezas, Nicaragua, and was moving northwest near 9 mph (15 kph).

The forecast track showed the storm could brush across the tip of Mexico's Yucatan Peninsula late Friday night and then hit the U.S. Gulf Coast as a hurricane by Sunday morning. Forecasters said hurricane conditions were possible in Mexico Friday night.

In the Pacific, former Tropical Storm Ramon dissipated off the southwestern coast of Mexico.