Gerardo Ramirez, a Central Texas dairy worker, was near his home but taking an unusual route to a children's hospital in April when he drove his Volkswagen Jetta into a flooded section of road, not seeing in the predawn dark that heavy rains had turned a tiny creek into a death trap. Ramirez survived, but his wife and two children drowned.

In March, 800 miles away in Lee County, Alabama, 23 people ranging in age from 6 to 93 were killed in a 170 mph tornado — despite an evacuation warning by local authorities just like ones that many residents had heeded in previous storms this year.

The deadly situations illustrate what experts increasingly see as two common reasons for unnecessary storm deaths: unfamiliar terrain that leads to bad decisions, and people ignoring too-familiar warnings that haven't panned out in the past.

Harnessing new prediction technology, federal authorities hope to sharpen the disaster warnings they send directly to cellphones, as well as to state and county emergency managers, to make the warnings faster and clearer about life-threatening conditions. They want to alert people like the Ramirez family who may be on unfamiliar terrain as unexpected disasters such as flash floods, tornadoes or wildfires unfold.

At the same time, social scientists working for the federal government are interviewing storm survivors like those in Lee County, gathering information for future advances in disaster warnings to combat "response fatigue" that can wear down people's sense of urgency, as apparently happened in Alabama.

Some of those who stayed put in Lee County had well-thought-out plans to evacuate, including gathering supplies, rounding up children and identifying a relative or friend in a more substantial house, said Kim Klockow McClain, who interviewed survivors.

"They rely on family resources, and frankly it can take all day to go and wait. People were losing money," said Klockow McClain, a scientist at the National Severe Storms Laboratory in Oklahoma, a research lab of the National Oceanic and Atmospheric Administration. "They just didn't go that day. It's as simple as that."

 

New flood alerts

 

To try to prompt residents to take action, in September the National Weather Service will change flash flood warnings to specifically mention whether the threat is "considerable" or "catastrophic," said Daniel Roman, a Maryland-based hydrologist at the National Weather Service.

Officials will make that call based on information from local weather spotters, radar evidence of tornado debris or computer detection of conditions that caused storms in the past.

The "considerable" flooding category calls for "urgent action" by residents and local authorities "to preserve lives and property," while the "catastrophic" category means waters are "rising to levels rarely, if ever, seen" and will "threaten lives and cause disastrous damage."

In November, after that system is in place, flood warnings sent to cellphones nationwide will be cut back to only those in the considerable or catastrophic category, less than 10 percent of the 12,000 flood warnings now issued every year to cellphones and local authorities, Roman said.

"The idea is that you cut back on the number, so you don't get the public desensitized," Roman said.

Warnings about more routine floods will still go out in other forms but won't buzz the area's cellphones.

The background noise of too many warnings can be just as dangerous as no warning at all.

"There are all these warnings and people are still driving into floodwaters," said W. Craig Fugate, a Federal Emergency Management Agency chief during the Obama administration and a former director of the Florida Division of Emergency Management.

"You can say 'Turn around, don't drown,' but there are so many flash-flood warnings that people tune them out and don't realize this one is more destructive," Fugate said. "Breaking through the noise is the challenge."

Impact-based warnings are already in place for tornadoes.

The idea came up after tornadoes killed 553 people across the country in 2011, the worst year since 1925.

Floods, tornadoes, wildfires and hurricanes killed 226 people last year, according to federal statistics.

 

Other alerts

 

The new format for flood warnings comes as the National Weather Service revamps other warnings to make them shorter and more specific about damage.

Starting Sept. 24, the service will cut back and simplify warnings on everything from fog to ice.

Impact-based warnings include more specifics to help people visualize what could happen — for instance, a severe hailstorm warning might say "people and animals outdoors will be severely injured," said Gregory Schoor, severe storms leader for the service.

Where disasters are a familiar part of life, such as Tornado Alley, people know the drill and generally respond quickly to disaster warnings and evacuation orders, many emergency managers say.

But meteorologists have recently begun to recognize the need to sharpen weather predictions to get attention in areas where residents may not be used to life-threatening storms.

Keith Seitter, executive director of the American Meteorological Society, said meteorologists look to research like Klockow McClain's for guidance on how to tailor future warnings for maximum effect.

"This is an issue for all meteorologists, and we take it very seriously," Seitter said.