MIAMI – Tropical Storm Ernesto took its sweet time over the storm-disrupting mountains of Cuba Monday afternoon, a modestly favorable development for Florida:

Ernesto still was predicted to directly strike South Florida on Tuesday – but as a strong tropical storm with 70-mph sustained winds rather than a minimal hurricane with 75-mph winds.

The distinction was slim, but certainly encouraging for a state hit or brushed by eight hurricanes in the past two years.

Still, forecasters emphasized that many storms have been known to rapidly intensify between Cuba and South Florida, and that Ernesto habitually has refused to adhere to forecasts.

“I can assure you that the probability is not zero that Ernesto could become a hurricane,” said Max Mayfield, director of the National Hurricane Center in West Miami-Dade County.

In addition, meteorologists said Ernesto – like many storms that arrive from the south – could produce more of a water event in Florida than a wind event. Five to 10 inches of rain could fall on parts of the region, swamping some areas.

With that in mind, long lines formed for fuel and food, officials in Miami-Dade and Broward ordered schools closed Tuesday, and limited evacuations were ordered or suggested.

“As long as we are preparing and not panicking, then everything will be okay,” Charlene Strauss said as clerks delivered bottled water to the empty shelves of an Albertson’s supermarket in Plantation.

With gasoline lines stretching for blocks in some areas, Gov. Jeb Bush praised South Floridians for taking pre-storm precautions, but urged them not to overreact. He said fuel inventories were abundant throughout the state.

A tropical storm warning and hurricane watch covered the Florida east coast from Vero Beach south through Broward and Miami-Dade and to Key West. That means tropical storm conditions are expected within 24 hours and hurricane conditions are possible.

Emergency managers urged everyone in the region to calmly begin shuttering their homes and businesses and otherwise preparing for Ernesto – preferably this evening, when the weather is still good.

Conditions will begin deteriorating Tuesday morning or afternoon, with forecasters warning of torrential rain, strong wind and the possibility of coastal and inland flooding.

The center of Ernesto reached Cuba’s southern coast Monday morning and forecasters predicted up to 20 inches of rain in some places. A report for Cuba’s Radio Rebelde said officials in Guantanamo and Santiago de Cuba were concerned that heavy rain could propel mudslides into coastal towns.

The system barely clung to tropical storm status as it slowly roamed over Cuba’s mountains. The duration of that trip substantially weakened Ernesto and should give it less time to regain strength over water before it reaches South Florida.

“I don’t think anyone is going to complain about that,” Mayfield said.

Meanwhile, ,managers of the Federal Emergency Management Agency prepositioned 70 truckloads of water and food at the Homestead Air Reserve Base, 50 truckloads in Jacksonville and 720 truckloads of ice elsewhere in the southeastern United States, according to Miami-Dade officials.

In other developments:

-At the Kennedy Space Center, officials scrapped all plans to launch Atlantis early this week and prepared to move the shuttle off the pad and back to its hangar, a laborious process that will keep the spaceship and its six astronauts grounded for at least 10 days – and probably much longer.

-Leaders of the Florida National Guard prepared to call up troops and deploy them where needed, according to spokesman Lt. Col. Ron Tittle. About 100 Guard soldiers, mostly experts in planning, will be called to active duty today, he said, with the main force likely to be called out Tuesday.

“We can bring in thousands of troops if necessary,” Tittle said.