Powerful winter storm hits eastern half of the US

The massive storm slamming the eastern half of the US is only one piece in a very active weather pattern. Multiple weather hazards are impacting the country Friday morning, so the National Weather Service has issued some kind of weather alert for every state.

Everything from blizzard warnings to tornado warnings are in effect early Friday as the massive storm works its way across the eastern half of the US. Wind alerts stretch nearly 2,000 miles from Texas to New England, while flood alerts span from the mid-Atlantic to Northeast.  

Another robust storm in the Northwest is bringing snow and wind to the region and temperature alerts dot several states as brutally cold air starts to seep south out of Canada. 

Alerts are in effect in Alaska ahead of a winter storm set to impact the state this weekend. Even Hawaii is dealing with the impacts of stormy weather as a potent cold front slices across the islands.

Track winter weather alerts across the US here.

The potent storm tracking across the central US will continue to strengthen on Friday, bringing all modes of hazardous weather to the eastern half of the country.  

At the storm’s peak intensity Friday night, it may strengthen enough to bomb out, or be considered a bomb cyclone: a rapidly strengthening storm that undergoes a significant drop in pressure — a measure of a storm's strength — in a short time. Bomb cyclones are formidable and unload heavy snow and strong winds during the winter. 

A storm must drop at least 24 millibars (which is a unit of pressure) in 24 hours or less to meet bomb cyclone criteria. But technically, the exact millibar drop needed will vary slightly based on the storm’s exact latitude.  

The Weather Prediction Center doesn't show the storm officially hitting bomb cyclone status, but several forecast models showed the potential exists. Bomb cyclone or not, it could end up stronger than the last powerful storm, which set January records for strength as it passed over Indiana.

Water levels on Maine's coast are forecast to hit historic highs on Saturday, threatening to inflict more damage on coastal communities still reeling after a storm earlier this week sent water surging onshore.

Water levels at gauges from Portland to Eastport were forecast to top levels from Wednesday during the last storm, according to data from the National Oceanic and Atmospheric Administration. Portland and Bar Harbor both hit new historic high-water marks on Wednesday.

The water level reached 15.49 feet in Bar Harbor Wednesday morning and is forecast to top 17 feet by noon Saturday. The previous record in Bar Harbor was 15.04 feet in 2018.

The water is projected to top 14 feet in Portland Saturday morning, slightly higher than the 13.84 feet hit on Wednesday morning, which broke the previous record set in 1978, NOAA said. 

Maine's governor issued a State of Civil Emergency Thursday for all eight of the state's coastal counties after the storm surge caused destruction there.

The exceptionally high water is being driven by strong winds blowing water from the Atlantic Ocean toward the shore on top of high tide. Heavy rain inland only exacerbates the flooding. 

Climate change is also playing a role. Sea levels are rising as global temperatures climb and melt glaciers and ice sheets. Higher sea levels are making coastal flooding events worse and will continue to do so in the future. 

Heavy, wet snow is moving across the Chicago area early Friday morning and could leave some parts of the metropolitan area with close to 6 inches of snow by the afternoon.

The National Weather Service in Chicago urged people across northern Illinois to "strongly consider postponing travel" Friday morning, warning of snowfall rates of 1 to 2 inches per hour.

The most snow will be largely in the western and northern Chicago suburbs Friday morning, away from the influence of Lake Michigan's abnormal warmth.

Snow will mix with rain across southern portions of the metro and areas along the lakeshore Friday afternoon, before changing back over fully to snow Friday evening once colder air arrives. Steady snowfall throughout the day will send totals skyrocketing for areas away from the lakeshore.

Very strong winds will arrive Friday evening across northern Illinois and combine with falling snow for another period of treacherous travel across the region, Chicago included.

More than 5 million people across portions of Texas, Arkansas, Louisiana, Tennessee and Mississippi are under a tornado watch as intense thunderstorms rumble across the South Friday morning.

The tornado watch is in effect until 11 a.m. CT and includes Little Rock, Arkansas, Shreveport, Louisiana, and Jackson, Mississippi.

Thunderstorms stretch from the Texas Gulf Coast as far north as Illinois and Indiana early Friday morning.

But the greatest risk for these storms to turn severe and unload damaging winds, hail and tornadoes is over the Lower Mississippi Valley, where a Level 3 out of 5 risk for severe thunderstorms is in place.

Another bout of rain will fall on the already-soaked Northeast on Friday, threatening to trigger disruptive and damaging coastal flooding in several of the region's major cities through Saturday.

More than 7 million people are under coastal flood warnings along swaths of the Northeast, including residents of Philadelphia and parts of New York, where Nassau and Suffolk Counties could be overwhelmed with up to 3 feet of coastline flooding.

"This will result in extensive road closures and flooding of low-lying property including parking lots, parks, lawns and first floors and basements of homes/businesses near the waterfront," the National Weather Service in New York warned. "Vehicles parked in vulnerable areas near the waterfront will likely become flooded and/or submerged."

In New York City, where a coastal advisory is in place, 1 to 2 feet of water could inundate ground-level areas. 

About 35 million people -- stretching from North Carolina to eastern Massachusetts -- are under flood watches Friday as the storm pushes through the eastern US.

More than 50 million people are under a severe storm threat across the Southeast on Friday after overnight storms brought high winds and almost a dozen reports of large hail in the South.

Parts of northern Alabama and Mississippi are the most at-risk for severe weather, with the main threats being powerful winds, large hail and a chance of tornadoes.

A tornado watch is in effect until 5 a.m. ET for parts of western and central Arkansas, northwestern Louisiana, southeastern Oklahoma and northeast Texas.

Other major cities in the storm's path include New Orleans, Atlanta, Nashville, Tennessee, and Tampa, Florida. 

As winter weather sweeps the country, more than 1,170 flights have been canceled within, into or out of the United States so far today, according to tracker Flight Aware.

In Chicago, which is set to receive more than 8 inches of snow, O'Hare International Airport tops the charts with more than 400 flights canceled in and out of the travel hub. The city's other airport, Midway International, is also among the hardest-hit with more than 100 cancelations.

Other airports with a high number of cancelations include Denver International Airport in Colorado, Milwaukee Mitchell International Airport in Wisconsin and Newark Liberty International in New Jersey.

Here's what to do if your flight is canceled or delayed.

Here's a look at the snowfall and other conditions expected in some of the Midwestern cities in the storm's path. All times are local to the cities indicated.

Chicago

Des Moines

Grand Rapids

Milwaukee

Minneapolis