Powerful winter storm hits eastern half of the US

The mayor of Buffalo, New York, says the area is prepared for this weekend's winter weather — and they're not expecting the type of storm the city dealt with in late 2022, when dozens died.

The forecast: The National Weather Service issued a winter storm warning for Buffalo and the surrounding area from 10 a.m. ET Saturday through to 3 p.m. ET Sunday.

The NWS said heavy lake-effect snow and very strong winds are expected. Blizzard conditions will be possible at times, especially late Saturday night and Sunday morning, according to the winter storm warning.

Preparations: Following the deadly 2022 storm, city leaders faced tough questions about their handling of storm preparations and the disaster response. Mayor Byron Brown said Buffalo is prepared for this new system. Its snow plan will be in full effect, and the city's emergency manager has met with different city departments.

Illinois Gov. J.B. Pritzker urged Texas Gov. Greg Abbott to stop dropping off migrants from the southern border during the intense ongoing winter storm.

Pritzker warned that sending migrants to Chicago this weekend could potentially cost lives.

CNN has reached out to Abbott’s office for comment.  

Maine officials say an iconic state landmark dating back to the 19th century suffered significant damage after it was struck by high waves and winds during the powerful storm sweeping across the eastern half of the United States.

Only one wall of the Pemaquid Point Lighthouse Park bell house, built in 1897, is still standing after 79 mph winds struck it Wednesday, according to Bristol Parks and Recreation Department director Shelley Gallagher.

Gallagher said that — with another powerful storm on the horizon — time is essential to ensure more harm isn't done to the building. Officials have taken steps to shore up what remains of the structure, but are "very concerned" it isn't enough, Gallagher said.

The bell house was built to store a 1,000-pound bell that alerted sailors when fog set in and they couldn't see the lighthouse, according to Gallagher.

Luckily, the bell was not damaged in the storm — it was moved at the end of August because the beam on which it hung was rotting.

Heavy snow and blizzard conditions will continue to blast portions of the Midwest. Strong winds will also ramp up across the region, reaching their peak once the powerful storm hits its full strength Friday evening.  

Thunderstorms will continue to roll across the Southeast, where some may become severe through Friday afternoon and evening. Rain and thunderstorms will arrive in parts of the mid-Atlantic by Friday evening and much of the Northeast will deal with rain and potential flooding by Friday night.  

Here’s what a few cities in the path of the storm can expect: 

Chicago: A mix of rain and snow Friday afternoon will gradually turn fully back over to snow Friday evening. Winds will remain gusty throughout the day, with gusts of 40 to 60 mph likely once again Friday night. Snow continues through Saturday as much colder conditions arrive.  

Atlanta: Thunderstorms will continue to develop and move across the city Friday afternoon. Some may become severe, with the potential for damaging wind gusts, hail and even a tornado. A Level 2 out of 5 risk for severe thunderstorms is in place Friday with the potential for damaging wind gusts, hail and even a tornado. Storms will exit the area Friday evening, but breezy conditions will linger through Saturday. 

Washington, DC: Rain and a few thunderstorms will arrive Friday evening and 1 to 2 inches of rain may drench some areas caught under heavy downpours. Winds will be quite strong with gusts of 30 to 50 mph possible. The combination of wind and rain may lead to power outages. Rain will taper off by early Saturday morning, but strong winds will persist. 

New York City: Rain, heavy at times, and strong wind gusts of 40 to 60 mph will arrive Friday night. Rainfall amounts of 1 to 2 inches are likely across the city, with higher amounts possible just north. Rain will taper off Saturday morning, but gusty winds will persist through the weekend.

Widespread wind gusts of 40 to 60 mph are likely across much of the Midwest and portions of the East as a powerful storm reaches its full strength Friday evening. Other portions of the central US will also get quite breezy Friday, with gusts of 30 to 40 mph possible.  

More than 150 million people across the US are under wind alerts as roaring winds crank up in intensity. Multiple locations in northern Illinois — including the Chicago metro area — reported wind gusts exceeding 50 mph Friday morning.

Power outages also started to increase Friday morning, with Illinois and Wisconsin accounting for more than 100,000 outages.

What's driving the winds: Severe storms aren't driving these strong, prolonged winds — it's the impressive strength of the storm, which is an area of low pressure, and how it interacts with a strong area of high pressure located off the northeastern coast of the US. 

The atmosphere is exerting pressure on all of us. The force of that pressure is lower under areas of low pressure and higher under areas of high pressure, hence the names. 

As the storm gets stronger, its pressure drops and it creates a stronger gap in pressure between it and the high pressure, known as a pressure gradient. 

The speed of the wind is related directly to the strength of the pressure gradient, because it squeezes the air that moves through it, forcing it to pick up speed. Think of it like popping bubble wrap: Once it’s squeezed hard enough, the plastic pops and the air quickly rushes out. 

The strength, duration and widespread nature of winds Friday in this pressure gradient are likely to bring down trees and cause additional power outages. 

The number of flight delays and cancellations is ticking up as the Midwest and South are experiencing messy conditions due to the storm.

According to the flight-tracking website FlightAware.com, there have been over 2,400 delays and 1,850 cancellations in the US today so far.

It's the highest number since July 2023, according to the data from FlightAware.

Chicago-area airports are leading that list, with O'Hare International Airport canceling almost 40% of its flights out and 36% of its inbound flights, and Chicago Midway International Airport canceling about 60% of both outbound and inbound flights.

Other affected airports include Denver International and Milwaukee Mitchell International.

Max factor: Cancellations due to the grounding of the 737 Max 9 planes are also contributing to the totals. More than 200 United and Alaska Airlines flights have been canceled each day this week due to the Federal Aviation Administration-mandated grounding. The FAA and Boeing are still trying to settle on an inspection protocol that would allow those planes to resume flying. 

Most of the cancellations, however, are due to the winter storm. FlightAware shows Southwest, which doesn’t fly the 737 Max 9, canceling nearly 400 flights — the most of any airline.

CNN's Ross Levitt and Pete Muntean contributed reporting to this post.

Power outages are climbing as the storm unleashes severe thunderstorms in the South, blizzard conditions in the Midwest and strong wind gusts for the more than 150 million Americans under wind alerts Friday.

Nearly 250,000 homes and businesses are without power in the Great Lakes and South as of Friday morning. Most of the outages are in Illinois, where more than 97,000 are in the dark, and winds have gusted as high as 55 mph at Chicago's O'Hare International Airport.

Severe thunderstorms racing across the South have produced wind gusts as high as 74 mph in Arkansas. 

Here are the top outages by state as of 10:30 a.m. ET:

Satellite imagery captured at least two flashes of lightning occurring over the Chicago area on Friday morning. What’s strange is, the city was experiencing heavy snow and not rain at the time.

Instead of a typical thunderstorm, what unfolded Friday morning was something called thundersnow. 

Thundersnow is exactly what the name suggests – a snowy thunderstorm. It’s a rare phenomenon that occurs in incredibly strong winter storms and sometimes during intense lake-effect snow.  

Typical thunderstorms are fueled by atmospheric instability, which develops from moisture and heat in the atmosphere. As such, lightning is much more common during warmer parts of the year or in warmer locations.  

But lightning isn’t impossible during cold months since very powerful storms like Friday's can generate plenty of atmospheric instability. A snowstorm can tap into this instability and produce lightning, which is exactly what happened over Chicago.

A snowstorm can tap into this instability and produce lightning, which is exactly what happened over Chicago.

The rumbles of thunder during thundersnow are often muffled by heavy snow. Despite this, lightning strikes during thundersnow are just as dangerous as a typical thunderstorm. 

As a powerful storm moves east across the US and continues to become stronger, it is enveloping more of the Midwest with snow.

Here are the top snowfall reports as of 10 a.m. ET:

Totals in these states will likely climb as snow continues to fall.

The storm has also been accompanied by powerful winds.

Here are the strongest wind gusts from thunderstorms so far:

And the strongest non-thunderstorm wind gusts: