What is an atmospheric river?
An atmospheric river is a narrow corridor of concentrated moisture in the atmosphere, often drawing moisture from tropical regions. When it moves over land, it can release substantial precipitation.
What is a bomb cyclone?
A bomb cyclone is a rapidly intensifying storm that experiences a significant drop in atmospheric pressure — at least 24 millibars within 24 hours — a process known as bombogenesis.
How are cyclones and atmospheric rivers related?
Cyclones form due to strong gradients in temperature and moisture in the atmosphere. As they form, they begin to spin, which enhances existing temperature and moisture gradients. An atmospheric river forms when a strong cyclone acts to draw moisture from the tropics and to concentrate it in a narrow band.
What happens during a bomb cyclone?
During a bomb cyclone, the storm’s central pressure drops rapidly, leading to intensified winds and precipitation. This can result in heavy rainfall, snow, strong winds and coastal flooding, depending on the storm’s location and the season.
Is a bomb cyclone dangerous?
Yes, bomb cyclones can be hazardous. Their rapid intensification can lead to severe weather conditions, including strong winds, heavy precipitation and coastal flooding, which can disrupt daily life and pose risks to safety.
Gusts from bomb cyclones can exceed hurricane force (74+ mph), causing downed trees and power lines, damage to buildings and flying debris, although the strongest winds typically occur over the ocean. The intense precipitation can cause flooding, mudslides and — if the air is cold enough — blizzards. Expect canceled flights, halted trains, road closures and car accidents.
How can people stay safe during a bomb cyclone?
During the storm, avoid going outside unless necessary. Avoid driving and stay away from fences and windows. If you must drive, check road conditions ahead of time and keep an emergency kit in your vehicle. If you’re in a flood-prone area, heed evacuation orders.
After the storm, look for hazards like downed power lines, unstable structures and flooding. Avoid standing water because it may hide dangerous debris or electrical hazards. Listen to local officials for updates on when it’s safe to return home or resume travel.
How often do bomb cyclones occur?
Bomb cyclones can occur several times a year globally, particularly during the colder months. The North Atlantic and North Pacific experience the most bomb cyclones.
What causes a bomb cyclone?
Bomb cyclones form when a midlatitude cyclone rapidly intensifies. This happens when there is a steep temperature gradient between contrasting air masses, such as cold, dry air meeting warm, moist air.
While climate change isn’t a direct cause, it can influence the frequency and intensity of bomb cyclones by altering atmospheric conditions.