Tropical Storm Alma weakened to a tropical depression Friday after slamming into Nicaragua's coast the day before, forcing tens of thousand of people to evacuate and flooding low-lying areas before pushing into neighboring Honduras.

By early Friday, the weather system's winds had fallen to about 50 km/h, according to the U.S. National Hurricane Centre in Miami. The storm was expected to dissipate by Saturday.

Officials at the National Hurricane Centre said Alma was the first tropical storm in the available records to make landfall on Central America's Pacific coast. Such storms normally make landfall farther west, in Mexico, and often move on to hit Central America's Atlantic coast.

Alma reached land Thursday near the Nicaraguan city of Leon where Mayor Transito Tellez said houses had been destroyed and power knocked out by the storm. Rescue personnel said some houses had their roofs had been blow off, and homes that had been crushed by fallen trees.

Nicaragua's Radio Ya reported that a 30-year-old man was electrocuted in Trasbayo, 64 kilometres southeast of Managua, after a power line snapped under high winds.

The fast-growing storm took forecasters and many in Central America by surprise. Residents scrambled to prepare for the storm before it hit.

People crowded Managua supermarkets to buy food, water, candles and batteries, and schools canceled classes and were on standby to become temporary shelters. Many flights were also grounded.

The storm wrapped the Costa Rican capital of San Jose in a dense fog, slowing traffic to a crawl and causing dozens of accidents.

Along the coast, some 200 families were evacuated to more than 160 storm shelters set up after Alma dumped rain over the country for 24 hours. Landslides blocked a few highways.

The eastern Pacific hurricane season began May 15.

With files from the Associated Press