Severe weather, tornado risk as storms slam East Coast. Updates

Powerful thunderstorms are barreling across the eastern United States, grounding flights, knocking out power and prompting tornado advisories as forecasters warn of worsening conditions.

More than 94 million people in the eastern half of the country were under severe weather alerts from the National Weather Service Storm Prediction Center.

Potent thunderstorms were expected from Florida to New York, with the highest risk of hurricane-force winds and tornadoes concentrated in the Mid-Atlantic region, including Washington, Maryland and Virginia.

"During the storm, stay inside," said Washington Mayor Muriel Bowser at a news conference, warning residents to seek shelter if they receive a tornado warning. She added it could take "several days or longer to get back to normal" if the storms cause significant damage.

Federal forecasters said the worst impacts will occur through the afternoon and into the evening. By 1 p.m., the storms had already caused thousands of flight cancellations, hundreds of thousands of power outages and widespread school closures.

Blizzard conditions in Michigan bring power outages

Some 360,000 people in the U.S. were without power early Monday evening, according to USA TODAY's Power Outage Tracker.

Nearly a third of the people, around 118,000, were in Michigan, where the northern half of the state was being hit with blizzard conditions. Over 2% of customers in the state were without power.

Up to five inches of snow and wind gusts as high as 45 mph were expected in portions of Eastern Upper Michigan and Northern Lower Michigan, according to the NWS.

Tornado watch around DC canceled 

DC-area NWS forecasters late Monday afternoon canceled a tornado watch for the area, though they warned of potentially damaging winds and temperature drops of up to 30 degrees overnight. 

Forecasters said high winds and thunderstorms remained possible until 10 p.m. local time. 

The easing of the forecast comes after many schools in the area were closed or dismissed early and after federal offices closed early. 

Record-breaking heat expected in Southwest

On the other side of the country, southeast California and southern Arizona are expecting record-breaking heat, according to forecasters.

Temperatures are expected to rise up to 109 degrees in the region facing the extreme heat, according to NWS forecasts. The heat spell is expected to begin Wednesday in California and Thursday in Arizona, ending Sunday.

According to NWS forecasters in Phoenix, the weather should feel "equivalent to June’s normal temperatures," and daily records could be broken by around 10 degrees.

The extreme heat warning is among the earliest on record, according to the NWS.

Weather issues rare risk for thunderstorms in DC region

The National Weather Service issued a "moderate" Level 4 out of 5 risk for thunderstorms across a swath of the East Coast, from Washington to northern South Carolina.

Such risk assessments are rare in the Mid-Atlantic region, and typically only happen two or three times per decade, according to the Capital Weather Gang.

There are an estimated 9 million people in the highest risk area associated with Monday's storms, according to the Storm Prediction Center.

"Multiple rounds of severe storms through this evening will yield potential for scattered to widespread damaging winds and a few strong tornadoes from the Carolinas into the Mid-Atlantic States," the center said in an outlook.

Workers take down flag at White House ahead of storms

Blizzards. Tornados. Near-record warmth. Why the weather whiplash?

The wild swings of weather the central and eastern United States has endured recently – from blizzards and bitter cold to severe thunderstorms and near-record warmth – are typical for March as the seasons transition from winter to spring, forecasters said.

"Wide temperature swings are normal as you get into meteorological spring, which starts on March 1," said AccuWeather senior meteorologist Courtney Travis in an e-mail to USA TODAY. "It’s during this time that you’ll start to see enough warm and cold air present in North America to get those larger temperature changes."

No other month experiences such dramatic temperature swings, and these wild fluctuations aren’t random chaos. They’re the result of two fundamentally different air masses fighting for control while neither has a clear advantage, according to weather-daily.com. Read more.

– Doyle Rice

North Carolina activates response team as storms ramp up

North Carolina Gov. Josh Stein on Monday said the state's Emergency Response Team has been activated to deal with calls for service as storms bring heavy rain and hurricane-force winds to the state.

"North Carolina, severe storms are moving across the state, bringing strong winds up to 74 mph and a chance of tornadoes and hail," Stein said on X. "The State Emergency Response Team is activated and ready to respond to any needs. Please make sure your emergency alerts are turned on and have a plan about where you’ll go if you need to take shelter."

Washington Monument closes early amid storm threat

The Washington Monument will close at 1 p.m. on Monday "due to anticipated weather conditions," the U.S. Park Police announced.

Officials will also close Hains Point, a peninsula in the Potomac River that's popular for recreation, in the early afternoon.

"Beware of possible flash flooding, standing water, strong wind, lightning and hail," the Park Police said in a statement. "Slow down. Stay off the roads in bad weather, if possible."

DC mayor warns residents of tornado threat, 80 mph winds

Mayor Muriel Bowser on Monday warned residents in Washington, D.C., of possible damaging winds and tornadoes as storms barrel through the Mid-Atlantic.

"What you need to know: 1. Tornado risk and damaging wind gusts of up to 80mph. 2. Heavy rain that could cause localized flooding. 3. Peak extreme weather 4-6PM," Bowser said in a post on X.

Power outages mount as storms intensify

Thousands of Americans are without power as severe weather slams the eastern half of the United States.

States in the Midwest and southern U.S. have been hit hardest by power outages as of 10 a.m. ET on March 16, according to USA TODAY's power outage tracker.

More than 131,000 outages have been reported in Michigan, while roughly 52,000 have been reported in Ohio. Towards the northeast, Pennsylvania has more than 30,000 outages, and New York has about 21,000.

– Melina Khan

Over 3k flights canceled as storms disrupt travel

More than 3,000 flights nationwide were canceled on Monday, according to FlightAware.

Most of the cancellations were concentrated in the central and eastern U.S., where a massive snowstorm and intensifying thunderstorms forced ground stops at airports.

New York City’s two largest airports led the disruptions with a combined 580 cancellations, followed by Chicago O’Hare International Airport (450), Charlotte Douglas International Airport (348), and Orlando International Airport in Florida (279).

Tornado watches, warnings issued across East Coast

Tornado watches and warnings were active from the Florida Panhandle to Virginia, as a large storm system began moving across the eastern U.S.

Around 10 a.m., the weather service office in Tallahassee issued a tornado warning, urging residents to "TAKE COVER" as meteorologists tracked a fast-moving storm in the area. A similar warning was issued for parts of Patrick County, Virginia.

"Move to a basement or an interior room on the lowest floor of a sturdy building. Avoid windows," said the weather service office in Blacksburg, Virginia. "If you are outdoors, in a mobile home, or in a vehicle, move to the closest substantial shelter and protect yourself from flying debris."

Where are severe weather alerts active? See map.

Blizzard conditions persist across the Great Lakes region

The expected storms are related to a cold front stretching east from a powerful winter storm bringing blizzard conditions to the Great Lakes region.

The intense cyclone is expected to dump another 8 to 10 inches of snow in Wisconsin and Michigan with up to 18 inches in Michigan's Upper Peninsula, bringing the two-day snowfall totals in the region to 2 or 3 feet.

The winter storm knocked out power to more than 120,000 homes and businesses in Michigan, according to a USA TODAY outage tracker.

Heavy rain in Florida, storms damage in Kentucky

Forecasters expected potent storms across parts of the Southeast, including in states such as Florida, Georgia, Tennessee and Kentucky.

Flash flooding is possible in South Florida, where more than 5 inches of rain has fallen in parts of the Everglades, the weather service said. Through the morning, rainfall rates of 2 to 4 inches an hour are possible, bringing an elevated risk of flash flooding.

Overnight, multiple buildings were severely damaged in Flaherty, Kentucky, with down trees and power lines, according to the weather service office in Louisville, Kentucky. In Sevier, Tennessee, wind gusts as high as 77 mph were reported.

Wild weather swings, from record high temperatures to freeze warnings

The severe weather across the nation is producing some intense weather swings, from sweltering heat in the Southwest to freezing temperatures in the Southeast.

This week, parts of Southern California, Nevada and Arizona were under extreme heat watches, with high temperatures 20 to 30 degrees above normal for this time of year.

"Dozens of daily high temperature records are expected, and many locations are likely to set both all-time high temperatures for March and their earliest 100 (degree) temperature on record," the weather service said.

Meanwhile, in the Southeast, states from Texas to Alabama to Georgia were under freeze warnings as a cold front moved through the region. Forecasters said the plunging temperatures could tie or break daily low records for March.

Christopher Cann is a national breaking news reporter for USA TODAY. Contact him via email at [email protected].