Atmospheric rivers are referred to as rivers in the sky. They cause serious issues when they dump their cargo onto the areas it covers. This plume of moisture transports a significant amount of water vapor from tropical areas into higher latitudes. This long, narrow band of tropical moisture is responsible for severe weather catastrophes by dumping unrelenting rain and snow on areas not equipped to handle these weather conditions without issues successfully.
In the western U.S., these atmospheric rivers account for 30% to 50% of the total annual precipitation. In contrast, these weather systems benefit the land by bringing rainfall to dry areas and are responsible for most of California’s water supply. However, there is a point where the amount of precipitation becomes more than the land can handle, leading to flash flooding, landslides, mudslides, and destruction, and may even result in deaths.
Atmospheric rivers happen all over the world and can hit several areas at the same time across the globe. According to The Weather Channel, these events are predictable and can be forecasted up to a week before they hit land.
In California, officials are urging residents to prepare for a powerful atmospheric event expected to hit the area with torrential rain within a week. Forecasters have warned that this atmospheric river could cause flash flooding as warm rain hits the snow-packed area still recovering from a past storm.
Climate change has an impact on atmospheric rivers, just like it does on the environment. As the world warms because of climate change, the atmosphere develops the ability to hold more moisture. More moisture in the air will result in rainier atmospheric river events and, therefore, more destruction and larger atmospheric rivers.
According to the United States Geological Survey, a high-intensity atmospheric river can be as destructive as a hurricane. There is a categorical system in place for these atmospheric rivers, like hurricanes—however, the ratings incorporate the idea that the atmospheric river could be beneficial, harmful, or possibly both.
The rating system ranges from one to five. As the category number rises, the level of hazard escalates.
Category one is considered weak and comprises around 24 hours of modest rainfall with primarily beneficial effects on the area the atmospheric event will affect.
Category two comprises a moderate storm that is mainly beneficial but has some hazards.
A category three atmospheric event ramps up to being categorized as a strong event. This event lasts longer and is more powerful than all the other categories but still has a balance of beneficial and hazardous impacts.
Category five escalates to being categorized as an extreme weather event. This category is when the atmospheric river becomes mostly hazardous while still having a few beneficial aspects. But at this point, the negatives out way the positives.
Lastly, a category five event is considered exceptional and is primarily hazardous. This event will cause severe damage, last an extreme amount of time, and could cost human lives.
Weather prediction models have improved and developed new methods to combat these systems. However, accurate predictions are still tricky due to all the unknown variables that can’t be predicted or accounted for. It is essential for areas to always be prepared and have plans in place to handle this extreme weather.
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