Tornadoes are powerful weather phenomena. While many people associate these events with daytime, tornadoes can and do happen at night, a reality important for safety.
The Occurrence of Nighttime Tornadoes
Nighttime tornadoes are a documented reality and not uncommon. Studies have shown that approximately 27% to 27.3% of all tornadoes in the United States occur between sunset and sunrise. Despite being less frequent than daytime tornadoes, these nocturnal events contribute to a disproportionately higher number of fatalities. Research indicates that nighttime tornadoes are about two to two-and-a-half times more likely to result in deaths compared to those that happen during the day.
Factors Contributing to Nighttime Tornadoes
The atmospheric conditions that foster tornadoes do not cease with the setting sun. While daytime heating provides energy for many storms, different mechanisms can sustain or initiate tornado-producing storms at night. One significant factor is the nocturnal low-level jet, a stream of fast-moving air that develops a few hundred meters above the ground after dark. This jet can transport warm, moist air and enhance wind shear, which is the change in wind speed and direction with height, a condition favorable for tornado formation.
Storm systems that form during the day can persist and even intensify into the night if the necessary atmospheric ingredients remain. Although surface temperatures cool after sunset, the instability higher in the atmosphere can still support powerful thunderstorms. This combination of a strong low-level jet and lingering atmospheric instability can allow severe weather, including tornadoes, to continue long after daylight fades.
Heightened Risks of Nighttime Tornadoes
Tornadoes striking after dark present heightened dangers compared to daytime counterparts. The primary challenge is significantly reduced visibility, making visual identification nearly impossible. Without daylight, a tornado may only be discernible through lightning flashes or power flashes as it disrupts electrical lines, leaving little time for reaction.
Many people are asleep during nighttime tornadoes, which can prevent them from receiving warnings promptly. This reduced awareness means individuals may not hear sirens or alerts, delaying their ability to seek shelter. Emergency services also face increased difficulties in assessing damage and conducting rescue operations in the dark, further compounding the hazards of nocturnal tornadoes.
Preparing for Nighttime Tornadoes
Given the increased dangers, specific preparations for nighttime tornadoes are beneficial. It is important to have multiple methods for receiving weather warnings that can rouse you from sleep. A NOAA weather radio, set to alert mode, can provide critical information even if power or cellular service is interrupted.
Ensuring your smartphone has weather apps with audible alerts enabled and sufficient volume can also serve as a valuable warning system. Establishing a pre-determined safe shelter location within your home and practicing drills, even at night, can help ensure a quicker and more effective response when every second counts.