Maelstrom

Maelstrom, as it was dubbed by the people who survived it, was named such as much of the aftermath was grief and confusion. One town would say how it sleeted so much, they were trapped in their homes and nearly froze to death in the spring. While the next town would talk about the tornadoes that ripped apart their town... in the end, we realized that all the stories were correct. You see Maelstrom wasn't just one storm, it was a mesoanticylonic supercell storm that blanketed the entire world for 7 days. In other words, it was a single massive storm made up of smaller storms that were feeding off each other.
We know of mesoanticylonic supercell storms because there is one on Jupiter that has been raging for 300 years. We've had them on earth before too... but never like this. Some cells of the storm made rain, others hail or sleet or snow. Winds ripped across the lands, spawning tornadoes, hurricanes and waterspouts. Dams couldn't hold the rising waters, they opened the flood gates to try to save the dams, it flooded the land but it wasn't enough, many dams gave way. Volcanos that hadn't been active for years suddenly rose to action, and earthquakes could be felt from California to the Philippines. The storm lasted for 7 days but the damage would take months to clear. In many areas, the sun was blocked out by toxic ash, it took weeks to settle to the ground so the sun could be seen again. Many people died in the storm, many more died in the months following it.
Governments fell due to either being destroyed by the storm or because they couldn't help people. When people realized no help was coming, well, anarchy took over. No rules, and only one law, survive by any means necessary.
What was the true cause of the Maelstrom? We don't know. There are theories that it was a Russian weather control machine that they'd lost control of. This was largely rejected as science fiction but then, it was also science fiction for the Maelstrom to have ever happened in the first place, so who knows. Many of the faithful declared it was end of days. Others said we'd treated the planet so badly that it was trying to rid itself of us. Still others theorized that perhaps this is what happened to the dinosaurs, perhaps it is part of the planets life cycle.

Entry for Worldbuilding Summer Camp 2023 Answering: "a destructive natural or supernatural event"

"We thought it was just a storm, like all the others. We were so wrong. Just before our phones died, we watched as the dam broke and three volcano's exploded all while New York drowned in a Tsunami.... it was nature purging us or it was the coming of Christ because it was the certainly the end."                                                      ~ Arthur Wright 85 yrs old.

Type

Natural