A massive heat dome has spread across much of the United States, putting 35 states and roughly 200 million people in the path of a dangerous, week-long stretch of extreme temperatures that could trigger serious and potentially life-threatening heat-related illnesses.
Heat domes form when a strong area of high pressure settles over a region like a lid, locking hot air near the ground, limiting cloud development and allowing intense sunshine to drive temperatures even higher.
Forecasters have described this summer system as a “mega” or “double heat dome” because two distinct high-pressure zones — one centered over the Southwest and another shaped by the subtropical Atlantic — have combined into one sprawling dome over the country.
Temperatures are forecast to climb beginning today and reach their most dangerous levels by Thursday, with communities from New York to Kansas bracing for heat index values above 105 degrees Fahrenheit this week.
The heat index reflects how hot it actually feels to the body when humidity is factored in. For example, on a 90-degree day, oppressive humidity can make conditions feel closer to 105°F.
Several major cities are already expected to see actual air temperatures hit 100°F on Thursday and Friday, including New York City, where the combination of heat and humidity could push conditions into a dangerous range for many of its nearly nine million residents.
AccuWeather meteorologist Matt Benz cautioned in a statement: “While temperatures during the day will be dangerous, the lack of any relief from the heat and humidity at night can be especially stifling and even deadly, especially for those that don’t have air conditioning.”
The National Weather Service also warned in its Extreme Heat Watch for the Northeast that “seniors and those with chronic health problems or mental health conditions are at an increased risk.”
A week-long heat dome is causing heat and humidity to build over more than 30 states, causing temperatures to rise dangerously high
Pictured: People enjoy a sun bath in New York City’s Central Park during the spike in heat on April 15 (Stock Image)
An Extreme Heat Warning has already been issued through Friday evening in portions of the Midwest, South and Mid-Atlantic, including in Illinois, Indiana, Missouri, Kentucky, Tennessee, Arkansas, Mississippi, Michigan, Wisconsin, Iowa, Kansas and Ohio.
The warning means NWS expects dangerously hot and humid conditions to cause heat exhaustion and heat stroke throughout the week’s heatwave.
An Extreme Heat Watch has been issued through Saturday evening in portions of the Northeast, including New Jersey, New York, Connecticut, Massachusetts, Rhode Island, Pennsylvania, Delaware and parts of Maine and New Hampshire.
NWS officials not issued a full warning for this region yet, but an Extreme Heat Watch means temperatures will likely reach this life-threatening level as the week progresses and the forecast becomes clearer.
AccuWeather Meteorologist Brandon Buckingham predicted: ‘While there will be a handful of locations that set record highs on a daily basis, there may be many more where record warmth occurs at night.’
A heat dome forms when the jet stream, the fast-flowing river of air high over the US, develops a bulge or ridge.
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This ridge creates a barrier that blocks normal weather patterns, allowing warm air to sink and get trapped under the ‘dome,’ while keeping storms and cooler fronts away.
AccuWeather meteorologist Carl Erickson explained: ‘Temperatures get magnified under a heat dome as sinking air associated with high pressure aloft bakes the air mass underneath it. The longer these features stick around, the hotter it tends to get at the surface of the earth.’
The National Weather Service has issued Extreme Heat Warnings (purple), Extreme Heat Watches (red) and Heat Advisories (orange) for millions of Americans this week
Pictured: Beachgoers enjoy the warm weather in Seaside Heights, New Jersey on April 15 (Stock Image)
High heat index values can lead to heat-related illnesses such as heat exhaustion or heat stroke within minutes of exposure.
Since humid air is already full of moisture, sweat evaporates much more slowly. That means your body cannot cool down well and it feels hotter than the actual thermometer says.
Elderly adults, children, those with chronic health issues, and those without air conditioning are expected to be at the greatest risk during the widespread humidity-induced heatwave.
Heat exhaustion often starts with heavy sweating, fatigue, developing cool, pale, clammy skin and a fast, weak pulse, muscle cramps, dizziness, nausea and headaches.
As for heat stroke, which is far more deadly and can develop within 15 minutes in extreme conditions, the first symptoms are often a throbbing headache, confusion, slurred speech, nausea, dizziness, and a fever above 103°F.
While two-thirds of the nation battle a dangerous heat dome through the Fourth of July weekend, Montana, Idaho and parts of Wyoming are seeing a shocking June snowstorm that will drop up to eight inches in many areas this week.
As a heatwave grips most of the US, three states have seen a surprise June snowstorm deliver nearly a foot of snow since Sunday
Winter Storm Warnings have been issued in multiple counties along the Idaho-Montana border on Monday, with officials warning that ‘wet snow may down trees and block access to forest roadways.’
Higher elevations in the mountains may see between 12 and 16 inches of snow, including in the Anaconda-Pintler and Lemhi ranges.
The surprise blizzard started Sunday after an unseasonably cold and slow-moving storm system moved into the region, causing temperatures to plummet by 20 to 30 degrees.
