At each National Weather Service (NWS) location across the United States, an enormous white sphere, resembling a giant soccer ball, sits atop a metal framework that reaches several floors into the sky. These spheres may appear mundane, akin to an ordinary water tower, yet they house one of the most transformative and lifesaving technologies in contemporary weather forecasting: Doppler radar.

This nationwide system comprises 160 high-resolution radars, first deployed in 1988 and later upgraded in 2012. These radars emit microwave pulses that reflect off precipitation such as raindrops, aiding meteorologists in assessing precipitation type and volume. This data is vital for early warnings about various weather events, including flash floods and snowstorms. The system is particularly critical for tornado detection, significantly increasing warning times and thereby reducing fatalities. “Doppler radar has truly transformed our ability to issue warnings,” notes Ryan Hanrahan, the lead meteorologist for NBC Connecticut’s StormTracker team.

However, meteorologists and emergency response planners are growing concerned over potential disruptions to radar operations, whether due to budget cuts under the Trump administration or the influence of conspiracy theories suggesting the radars manipulate weather. “Losing radar capabilities would set us back four decades,” states Jana Houser, a tornado expert at Ohio State University. Without these radars, effective storm warnings would be nearly impossible.

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Understanding Doppler Radar Technology

The NWS utilizes a system known as the Next Generation Weather Radar, or NEXRAD. Within each large white dome, there is a sophisticated apparatus akin to a large satellite TV dish. This device emits microwave pulses that reflect off objects in the atmosphere—termed hydrometeors—like raindrops, snowflakes, and hail, and even bats, birds, and moving trains, which can be identified by their unique radar signatures.

The returned signals enable experts to visualize the size, shape, and intensity of precipitation, appearing on weather radar displays on smartphones and television broadcasts.

NEXRAD’s capabilities extend beyond mere precipitation tracking. Each unit rotates and scans vertically, allowing forecasters to examine various levels of a storm system. This ability is crucial for detecting potential tornadoes or downbursts. “Doppler radar essentially allows us to see inside the clouds,” Hanrahan explains.

The term “Doppler” itself refers to the Doppler effect—most commonly experienced with the changing pitch of a passing siren. In radar technology, this effect helps differentiate the movement of particles within a storm. For instance, a raindrop moving towards the radar shortens the wavelength of the reflected signal, while one moving away lengthens it. This feature is particularly useful for pinpointing the rotation within tornadoes.

In 2012, the radar system was enhanced to include dual-polarization, which sends and receives both horizontal and vertical signals, providing a three-dimensional view of precipitation. “A small raindrop returns similar signals in all directions, but larger ones, shaped more like hamburger buns, reflect more horizontally than vertically,” Hanrahan adds.

Doppler Radars: Safety and Weather Impact

Doppler radars are safe for humans, animals, and buildings, and they do not influence weather patterns.

On the electromagnetic spectrum, it’s the shorter wavelengths like gamma rays and ultraviolet rays that can harm human tissue, as they can interfere with DNA. Doppler radars, however, emit microwave signals roughly the size of a baseball, which are not harmful to biological tissues at typical exposure levels.

Extreme exposure to concentrated microwave radiation can be harmful—this principle is why microwave ovens are shielded. Similarly, standing directly in front of an operational radar beam is inadvisable, as was discovered by military personnel who experienced rapid heating effects. However, at a distance, the radiation levels from Doppler radars are negligible, explains Cynthia Fay of the NWS Radar Operations Center.

At the radar dish, the energy output can be substantial, but this power diminishes sharply with distance. “By the time you’re miles away, the radar’s energy is inconsequential,” notes Daniel Swain, a climate scientist from the University of California, Los Angeles.

Doppler radars are mainly receptive devices, spending the majority of their operational time listening rather than transmitting. The notion that these radars can control weather is a longstanding conspiracy theory, recently highlighted by threats against the National Oceanic and Atmospheric Administration’s radar installations from an antigovernment group, as reported by CNN. The NWS has advised radar technicians to take precautions and coordinate with local law enforcement when necessary.

Consequences of Radar Outages

NOAA’s radar network operates nonstop, providing invaluable data since 1988. “These radars are incredibly reliable workhorses,” says Hanrahan. However, they do require regular maintenance, which could be jeopardized by budget cuts and staffing reductions under recent federal administration policies.

The potential for radar outages is a significant concern for meteorologists, especially during severe weather events. “Radars are crucial for issuing accurate tornado warnings,” Houser explains. “If we lose a radar, we lose our ability to see the broader meteorological picture.”

In many parts of the U.S., particularly the West, radar coverage has little redundancy, meaning that if one radar fails, nearby systems cannot compensate. The advancements made with the 2012 upgrades are critical, Hanrahan notes, allowing forecasters to detect tornadoes without direct visual confirmation—an often underappreciated capability.