US Heatwave: Understanding Heat Domes and Climate Change Impact

Widespread Heatwave Across the US

• 🌡️ A significant heatwave is blanketing much of the U.S., with over 200 million people expected to experience temperatures above 90 degrees.
• 📈 Tens of millions are facing triple-digit heat, particularly in the desert Southwest, but the impact is spreading nationwide.
• ⚠️ Dangerous heat is forecast for many parts of the central plains and upper Midwest, with the East Coast also expected to be affected in the coming days.

Understanding the Heat Dome Phenomenon

• ☁️ A heat dome is described as a "force field" of hot, dry, sinking air that expands vertically in the atmosphere.
• ☀️ This phenomenon suppresses rising air and cloud cover, leading to more sunshine and allowing temperatures to bake for extended periods.
• ➡️ Heat domes can deflect weather systems and shunt the jet stream northward, causing the extreme heat to become stuck in the atmosphere for days.

Duration and Impact of the Heat Event

• 🗓️ The current heat event is characterized as expansive and long-duration, expected to last from Saturday into Wednesday or Thursday before relief arrives.
• 🏜️ While triple-digit heat is common in places like Phoenix, it is also affecting areas like Omaha, Albuquerque, and Denver.
• 💧 Warmer overnight lows, exacerbated by a wetter atmosphere trapping heat, are contributing to exacerbated heat stress.

Climate Change and Extreme Heat

• 🔥 While heat domes occur naturally during summer, climate change is tipping the scales towards hotter, longer, and more geographically expansive heat events.
• 📉 The fingerprint of climate change is evident in the trend towards more warm events and fewer significant cold events.
• 💨 Although some historical records from the 1930s show extreme heat, current events are characterized by higher atmospheric moisture, making the heat more intense and overnight lows more concerning.