Heatwave Alert: Millions in the U. S. Face Dangerous Conditions

The U.S. is bracing for a severe heatwave this weekend, with a significant portion of the Eastern region under threat. By Sunday, a staggering 38 million people will be at "major" risk of heat stress, while another 7 million could face "extreme" danger, according to the National Weather Service.

Regions at Risk

• Midwest and Central Plains: Expected to experience the highest temperature anomalies, with mercury levels soaring to the mid-to-upper 90s Fahrenheit (mid-to-upper 30s Celsius).
• High Humidity: The combination of scorching heat and high humidity will lead to perilous wet-bulb temperatures, pushing the human body's cooling mechanisms to their limits.

Heat Advisories

• Issued in 15 states: Stretching from Nebraska to Florida, starting Friday.
• Effective through Monday.
• Hardest-hit areas:
• Northern Illinois on Sunday.
• Central Iowa, Missouri, Northwestern Tennessee, and parts of west-central Florida.
• Monday: Extreme risk could spread to central Tennessee, western Kentucky, and southwestern Indiana.

Safety Measures

The National Weather Service advises:

• Stay hydrated.
• Seek air-conditioned spaces.
• Avoid direct sunlight.
• Check on vulnerable neighbors and relatives.

Understanding Wet-Bulb Temperature

• Crucial Metric: Combines heat and humidity to assess heat stress.
• High Humidity: Hampers the body's ability to cool itself through sweat evaporation, increasing the risk of heat-related illnesses, especially for children, the elderly, and those with chronic health conditions.

Wet-Bulb Globe Temperature (WBGT)

• Comprehensive Measure: Factors in air temperature, wind speed, cloud cover, and solar radiation.
• Expected Values: Upper 80s and low 90s Fahrenheit (low 30s Celsius) across the Midwest and Southeast.
• Danger Threshold: Values exceeding 90 degrees Fahrenheit (32 degrees Celsius) can cause heat stress in just 15 minutes of outdoor activity.

Historical Context

• Late July Heat Dome: Led to warnings for nearly 170 million Americans as WBGT values skyrocketed.
• Global Warming: Extreme wet-bulb conditions are becoming more intense and prolonged, highlighting the importance of WBGT in assessing human survivability in a changing climate.