A record-shattering heatwave that has roasted the US Southwest this week is expanding east, threatening millions with hazardous conditions if they go outdoors.
Meteorologists warn that 23 states are expected to fall under the massive heat dome spreading into the Central US on Friday and Saturday, sending temperatures up to 30 degrees above the normal average for late-March.
Days after extreme heat warnings were issued in California, Nevada and Arizona, AccuWeather has said the summer-like conditions will now engulf the Dakotas, Nebraska, Kansas, Texas, Oklahoma, Arkansas, Missouri, Iowa, Illinois and Indiana.
A heat dome works like a lid of high pressure. It builds overhead, trapping hot air at the surface level, suppressing clouds and intensifying sunlight.
Temperatures in multiple states, such as Texas and Nevada, are expected to hover around or surpass 100 degrees Fahrenheit, breaking records which have stood for decades.
In the Midwest and Great Plains, the heat will push into the 80s this weekend, far above normal March averages which typically stay between 40 and 60 degrees.
The National Weather Service (NWS) has also issued ‘hazardous weather’ warnings throughout the region as the heat and extremely dry conditions are expected to trigger widespread wildfires.
The historic heat across the Southwest has already set new daily temperature records in at least 30 cities in California, Oregon, Idaho, Nevada, Arizona, Wyoming, Colorado and New Mexico.
Temperatures across 23 states are expected to be between 15 and 30 degrees hotter than the normal average for late-March (Stock Image)
A massive heat dome which has formed over the Southwest is now expanding east, pushed by weather patterns in the Pacific Ocean
A heat dome forms when the jet stream, the fast-flowing river of air high over the US, develops a bulge or ridge.
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.
The heat dome has now moved east because the large area of high pressure over the western US has been pushed along by weather patterns from the Pacific Ocean, causing the dangerous system to expand all the way to the Great Lakes.
This system will have a major impact on areas still digging out from an intense winter where feet of snow fell in most northern states.
AccuWeather Senior Meteorologist Tyler Roys said: ‘The building heat and abundant sunshine will accelerate snowmelt in the high country and rapidly dry out vegetation at lower elevations.’
‘Where winds increase, the risk of wildfires will rise, while lighter winds could allow pollutants to accumulate.’
Forecasters warned that the extreme heat is now expected to last into early next week, with temperatures in the Southwest remaining dangerously high and in triple-digits in many areas.
Officials with NWS have warned the public to stay indoors during the hottest parts of the day this weekend, and also to take frequent breaks in the shade or in air conditioning if you have to be outside.
Over 30 cities have already set new records for the hottest March day this year
The weekend forecast is expected to continue setting new records for heat months before the arrival of summer
Multiple cities, including Phoenix, Las Vegas and Palm Springs, California have already set new records for hottest day in March.
AccuWeather said Dallas and Austin, Texas could both challenge their records this weekend, with both cities expected to approach 100 degrees on Saturday. That would shatter marks set for the hottest March day which have stood for over a century.
NWS has urged anyone under the heat dome, and especially in areas exceeding 90 degrees, to take action immediately if they see symptoms of heat exhaustion and heat stroke.
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 degrees Fahrenheit.
Sufferers may also develop red, dry, or damp skin, a rapid pulse, and lose consciousness.
Move anyone affected by these conditions into a cool, shaded spot right away and call 911.
