Hurricane Harvey made landfall on the Texas coast late on Friday as a Category 4 storm, a designation meaning it was capable of causing devastating damage. Even though the hurricane was downgraded soon after making landfall, it was expected to linger, prompting the National Weather Service to warn on Sunday: “This event is unprecedented and all impacts are unknown.”

Since then, at least 10 people have been killed and many more injured in the storm, which had unleashed more than 40 inches of rain by Tuesday with the expectation that more will fall through Wednesday.

Officials have been grasping for superlatives. Gov. Greg Abbott of Texas called the storm “one of the largest disasters America has ever faced.” Local, state and federal officials have conceded that the scale of the crisis is so vast they were nowhere near being able to measure it, much less fully address it.

Words may escape politicians, but measuring and describing a storm is exactly the job description of forecasters.

“We wanted to convey the message that this is a storm that can kill you,” said Dennis Feltgen, a meteorologist with the National Hurricane Center in Miami.

While Mr. Feltgen noted there were similar dire warnings for other devastating hurricanes like Katrina in 2005 and Sandy in 2012, Hurricane Harvey stood out. The predicted deluge of up to 50 inches of rain tops what Houston receives in a year.

“It is unprecedented in terms of rainfall,” Mr. Feltgen said. “We use the terms catastrophic and life-threatening, and that is exactly what it was.”

Mike Brennan, a meteorologist with the hurricane center, said much of their challenge lies in trying to make citizens visualize what a unit of measurement means. That sometimes leads to translating the arcane language of weather science.

“Twenty-five to 30 inches of rain is hard for people to picture what that means,” Mr. Brennan said. “There is a whole social science angle to our product. It’s not just the numbers. It is the hazard: 130 m.p.h., well what does that mean?

“A storm surge is a different animal. You are talking about how many feet of water, and trying to convey this is a life threatening storm surge,” Mr. Brennan said. “This is going to be taller than your children, or higher than your house, and that’s where you come up with catastrophic and life-threatening wording, and push that message out.”

The National Weather Service has devised guidelines exactly for the purpose of making their predictions digestible. For example, some sizes of hail are described not just in terms of inches but in comparison to real world objects. Would you be more afraid of 4-inch diameter hail or grapefruit-size hail?

“You just can’t throw science at them,” Mr. Brennan said. “We are scientists; we like numbers and technical knowledge, but we need to use plain words.”

“People are bombarded with messages,” he added. “So you try to point them to the hazards.”

That is the job of Elliott Jacks, who delves into the semantics of weather as the head of a National Weather Service project to simplify the language its forecasters use to describe hazards. The fittingly named Hazard Simplification Project is working with social scientists who are experts in how the public perceives risk and messaging.

The idea, Mr. Jacks said in an interview, is to create a standardized catalog of words that meteorologists can pull out to describe pre-defined weather conditions. For example, reserving the use of the word “catastrophic” for only some extremely violent storms, would make it more of a common call to action rather than a description of just one episode.

But true to its legacy, Harvey evaded description, particularly when it was referred to by the weather service as “beyond anything experienced.”

“I have not heard anything like that,” Mr. Jacks said. “It is actually the right language. Our forecasters on the spot are being really very creative in making people understand, and to save life and property. And that is where their heads are at when they are creating that kind of language.”