A severe windstorm in Colorado last week caused a momentary disruption to the United States’ official time standard, UTC(NIST). While the change was minuscule – 4.8 microseconds – it highlights the surprisingly fragile infrastructure that underpins global timekeeping.
The Disruption at NIST
The incident occurred when hurricane-force winds triggered widespread power outages in Colorado, including at the National Institute of Standards and Technology (NIST) in Boulder. NIST maintains a network of atomic clocks, primarily hydrogen masers and cesium beams, which serve as the foundation for UTC(NIST). These clocks are designed to run on battery backup, but the storm caused a failure in the facility’s backup generator, temporarily disconnecting some of these clocks from NIST’s measurement systems.
This disconnection led to a slight slowdown in the official US time standard. The difference, though tiny, is critical because UTC(NIST) is distinct from the globally coordinated time standard (UTC) and influences various high-precision systems.
Why This Matters
Although 4.8 microseconds is imperceptible to humans (a blink takes 572,000 microseconds), the implications for sensitive technologies are significant. Telecommunications, GPS signals, financial markets, and critical infrastructure all rely on precise time synchronization. Even minor deviations can disrupt these systems.
Jeff Sherman, a supervisory research physicist at NIST, explained to NPR that the clocks themselves continued functioning, but the automated systems responsible for measuring and distributing the time signal were affected. The NIST facility uses primary and alternate multi-channel measurement systems (MCMS) to detect even the smallest temporal shifts, which are then fed into algorithms determining the official US time.
Correction and Ongoing Reliability
Power has since been restored, and the NIST team has corrected the blip. The incident serves as a reminder that even the most advanced timekeeping systems are vulnerable to real-world disruptions. The US’s reliance on atomic clocks for critical infrastructure underscores the importance of robust backup power and redundant systems.
This event also highlights how closely connected global timekeeping is: the US standard contributes to international efforts to maintain accuracy, and even a minor local disturbance can have ripple effects.
The NIST facility is operational, but the incident raises questions about long-term resilience and the need for improved safeguards against extreme weather events.
