Ring of Fire

During the summer of 2023, we learned about the Omega block, a weather pattern shaped like a Greek letter that locks in conditions for extended periods. Though this phenomenon is hardly rare, we often barely notice its existence. Sometimes it produces heat domes that trap high temperatures in regions for weeks or months on end; conversely, sometimes it brings unseasonably cool temperatures to locales. The 2023 iteration, though, left quite an impression on many residents of the United States. This Omega block funneled smoke from Canadian wildfires into parts of the nation typically unassociated with apocalyptic air quality. For days and weeks, swaths of the eastern U.S. lived under smoke warnings, all thanks to the pesky interplay of high and low pressure.

This event was notable but the more frequent result of atmospheric blocks is the aforementioned heat dome. Southwestern and southern portions of the United States increasingly bake under domes that sit like stubborn toddlers when you need them to move. The one upside to a heat dome is a lack of severe weather. Heat domes occur under high-pressure systems, which preclude inclement weather. Of course, the trade-off is unrelenting sun and temps that can melt asphalt.

Severe weather (or even just rain) often rides along the boundaries between high and low pressure. High pressures generally equate to fair, sunny skies, while low pressure indicates precipitation is moving or has moved through an area. During a block, low pressure and the bad weather it brings cannot penetrate the high-pressure areas.

A weather report from WHAS in Louisville shows rain along the boundaries between high and low pressure

So, what happens when an unstoppable storm front meets an immovable heat dome? As we saw with the Canadian smoke, the systems tend to flow around the high pressure. In an Omega block, the fronts swirl around the continent like rollercoasters.

In the southern United States, when the Greek shapes do not accompany a heat dome, they tend to look like circular bubbles.

A monster heat dome from September 2022 - graphic by KCRA

If you’re reading this article in publication order, you know this issue is the fourth consecutive to don the same title. We watched a Ring of Fire illuminate (or dim, depending on your glass-half-full, glass-half-empty stance) our skies; we investigated a Ring of Fire in the Earth’s crust, which produces earthquakes and volcanoes; we learned about a gorgeous cultivar of sunflowers that seem to mimic the annular eclipse; and, now, we have one on our weather maps.

If thunderstorms proliferate along the margins of a heat dome, sometimes the result lights up a radar like a lightning-fueled circlet. Meteorologists dub this happening a Ring of Fire.

If conditions are right, storms can whirl around the ring, bringing potentially severe weather to the land on the border. 

A Ring of Fire setup - graphic by WQAD
Ring of Fire map by Weather.com

When a ring is firing on all cylinders, heat energy from the dome mixes with the storms along the boundaries to create giant pockets of supercells.

This weather pattern is a prime creator of another past topic of the project: derechos. These intense storms span great distances (more than 240 miles), last for many hours, and produce tornado-like winds without rotation or funnels. The singular direction of derechos often earns them the title “straight-line winds” and they move in squall lines. The breadth of a derecho’s destruction can be much greater than a singular tornado, though often less intense in specific localities.

If a Ring of Fire is set up, derechos can spring up along the edge and ride the circle for hundreds of miles. In 2012, the “Ring of Fire derecho” covered more than 600 miles from Illinois to the Atlantic Ocean after rolling off the top of a massive heat dome.

The radar life of the famous 2012 derecho - graphic by NWS/Storm Prediction Center

If you’re keeping score, two natural phenomena known as a Ring of Fire pose little destructive threat to living organisms or property, while two can demonstrate the latent fury of Earth.

Like the Johnny Cash tune, a Ring of Fire can be pretty and it can burn, burn, burn at the same time. The most extraordinary natural things can sometimes combine beauty and devastation. Thankfully, if you want a taste of the ring without annihilation, you can stick to sunflowers.

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