Richard Rowe / Reuters

A tornado near El Reno, Okla., on May 31.

The tornado that struck El Reno, Okla., on Friday night is believed to be the widest on record in the United States at 2.6 miles across, the National Weather Service reported on Tuesday.

The May 31 twister beat the previous record, a 2.5-mile wide storm that struck Hallam, Neb., on May 22, 2004.

The Friday tornado and its resulting flooding claimed 18 lives, including six children and a dozen adults, the Oklahoma Medical Examiner reported on Tuesday. Six of the victims remain unidentified. Area hospitals treated 115 injuries after Friday’s storm, the Oklahoma Department of Emergency Management said.

The tornado’s width was measured by a mobile radar unit as the storm passed south of El Reno near Highway 81, the NWS said. The measurement only includes the tornado itself, and not winds surrounding the storm.

The tornado was also upgraded to an EF-5 classification, the most forceful category, according to the NWS.

El Reno is about 25 miles west of Oklahoma City.

The massive tornado struck less than two weeks after a tornado ripped through nearby Moore, Okla., leaving 24 people dead.

Governor Mary Fallin declared a state of emergency in 41 counties as the storm-battered region recovered on Tuesday. Search and recovery efforts continued for victims who went missing after being swept away by Oklahoma River floodwaters, NBC News affiliate KFOR reported.

Related:

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• 12 dead in aftermath of tornadoes, floods
• More Oklahoma twisters!? Latest outbreak fits Tornado Alley’s pattern

Storm-battered Oklahomans again faced the risk of severe thunderstorms and even tornadoes on Tuesday as another storm system moved through the Plains and the Mississippi Valley, forecasters said.

Slideshow: Tornadoes hit central Oklahoma

KFOR-TV

Click to view scenes from Friday's violent storm.

Launch slideshow

Weather Channel meteorologist Kevin Roth said that isolated tornadoes were possible, along with damaging wind gusts and hail.

Severe thunderstorms were possible in the east and south Plains and the Mississippi Valley on Tuesday and the south Plains and north Texas on Wednesday, Roth said.

“Hard-hit Oklahoma has the severe threat both Tuesday and Wednesday,” he added.

He said there was a tornado risk for Oklahoma City late afternoon and evening on Tuesday.

“Strong thunderstorms” were also expected to hit Kansas City on Tuesday afternoon.

The National Weather Service published a map showing a large swath of the central and eastern U.S. at risk of thunderstorms and parts of Texas, Oklahoma, New Mexico, Arkansas, Kansas and Missouri had a slight risk of severe storms.

“Primary threats will be large to very large hail and damaging wind gusts. Isolated tornadoes will also be possible,” the weather service said.

Residents of West Alton, Mo. were ordered to evacuate the town after a levee breach near Highway 67 that sent water gushing over the roadway, Fire Chief Richard Pender told NBC News affiliate KSDK.

A flash-flood warning was in effect for parts of McClain, Grady, and Cleveland counties in Oklahoma until 7:15 am local time, the National Weather Service reported, as heavy rainfall was expected to move through the area.

The nation's midsection has been battered by relentless storms in recent weeks. On Friday, severe weather began to sweep across through the region, leaving 21 dead from twisters, hailstorms and flash floods - most of them in Oklahoma and Missouri.

And on May 20, an EF5 tornado packing 210mph winds struck the Oklahoma City suburb of Moore, killing 23 including 7 children who died at an elementary school.

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This story was originally published on Tue Jun 4, 2013 5:34 AM EDT

Ferocious storms that battered Oklahoma and Missouri, killing 21 over the weekend, lurched eastward Monday, lashing New England and the mid-Atlantic region with harsh winds and heavy rainfall before moving out to sea.

Although the East Coast may be struck by another round of thunder Monday, forecasters at the National Weather Service said the severe storm threat has largely passed, bringing an end to several days of violent weather across a wide swath of the country.

At least 18 people — including six children and three storm chasers — were killed after five twisters attacked the Oklahoma City area Friday evening, terrorizing communities already bludgeoned by lethal storms this spring. Another three people died in Missouri.

Authorities were still searching Monday for five missing people – including three children – from areas around the Oklahoma River, according to Oklahoma City Fire Department Deputy Chief Marc Woodard.

Hospitals in Oklahoma City reported 115 injuries, officials at the Oklahoma State Department of Health said late Sunday, although that number may have increased Monday as officials began to reckon with the devastation wrought by Friday’s swarm of storms.

The twisters hammered the Oklahoma City area just 11 days after a monstrous tornado claimed 24 lives in the suburb of Moore, where power outages were reported Friday during the height of the twisters’ tear through town.

The three fatalities in Missouri were blamed on fierce flooding caused by the punishing hailstorms the wild weather system brought to large parts of the heartland.

"Authorities have confirmed three deaths from high water; those occurred in Lawrence, Miller and Reynolds counties," said a statement from Missouri governor Jay Nixon’s office.

The Weather Channel confirmed at least three tornadoes touched down around St. Louis, badly damaging homes but not causing any fatalities. 

Slideshow: Tornadoes hit central Oklahoma

KFOR-TV

Click to view scenes from Friday's violent storm.

Launch slideshow

Communities on the East Coast were hit with some wild weather conditions Sunday evening, including rough winds and torrential rainfall, but the storm threat had largely subsided by Monday.

“The risk of severe weather has pretty much disappeared on the East Coast,” Bruce Terry, a meteorologist with the National Weather Service, told The Associated Press.

At the height of the Sunday evening assault on the East, over 40,000 homes and businesses were left without power in Vermont, New Hampshire and Maine, according to The Associated Press. But more than half of those structures had electricity restored by Monday.

Washington, D.C., was also pounded by showers and thunderstorms Sunday evening, but the skies above the nation’s capital were mostly clear Monday.

Finally, residents of Anderson County in upstate South Carolina reported possible tornado sightings Sunday, authorities said. At least one house was hit and had its roof torn up, but there were no reported injuries Monday morning, according to County Administrator Rusty Burns.

NBC News' M. Alex Johnson, Janet Shamlian, Aaron Marmelstein and Alastair Jamieson contributed to this report.

Related:

• Storm chaser caught in twister: It felt like I was going to heaven
• More Oklahoma twisters!? Latest outbreak fits Tornado Alley's pattern
• Midwest tornadoes like a giant game of Battleship

This story was originally published on Mon Jun 3, 2013 3:47 PM EDT

Violent storms that left at least 16 people dead in Oklahoma and Missouri were heading towards the Northeast and Mid-Atlantic Sunday, as the nation’s mid-section struggled to cope with floodwaters.

At least 13 people –including nine adults, three of who were storm chasers, and four children — were killed after five tornadoes — one a half-mile wide — struck the Oklahoma City area Friday evening, terrorizing communities already battered by deadly storms this spring.

The Oklahoma City Fire Department on Sunday was also searching the Oklahoma River for four more missing people. 

Hospitals in Oklahoma City reported 115 injuries, according to the Oklahoma State Department of Health.

One of the dead was named by the Oklahoma County Sheriff's Office as James C. Talbert, 65, whose vehicle drove off a washed-out bridge in eastern Oklahoma County Saturday.

Three further deaths, in Missouri, were blamed on flooding caused by the torrential hailstorms that the weather system brought to large parts of the mid-US. 

"Authorities have confirmed three deaths from high water; those occurred in Lawrence, Miller and Reynolds counties," said a statement from Missouri governor Jay Nixon’s office.

The Weather Channel confirmed at least three tornadoes touched down around St. Louis, badly damaging homes but not causing any fatalities. 

Tens of thousands were without power, and only eight minor injuries were reported. Gov. Nixon declared a state of emergency. After touring the damage on Saturday, Nixon told The Weather Channel that "dozens of houses literally exploded" in Charles County, where an EF3 twister ripped through. 

Three "storm chasers" who had done work with The Weather Channel were killed in Friday's tornadoes. Father and son team Tim and Paul Samaras, as well as chase partner Carl Young, were killed as a result of a twister in El Reno, Okla.

"They went in the field focused on collecting data to enable meteorologists to further the science behind tornadoes which we know has and will help to save countless lives," The Weather Channel said in a statement. "Our community has suffered a terrible loss and our thoughts and prayers are with their loved ones."

The twisters came just 11 days after a monster tornado left 24 dead in the Oklahoma City suburb of Moore, where power outages were reported Friday.

"The last two nights, I've been having hell," Roy Stoddard, a truck driver from Depew, Okla., who was delayed by rising floodwaters at Little Rock, Ark. on Thursday told The Associated Press. On Friday evening, he had to take shelter in a store's walk-in cooler during Friday evening's rush-hour in Oklahoma City as deadly weather approached.

"I know what a tornado can do," Stoddard added.

The weather system had started lurching eastward Sunday, bringing scattered thunderstorms, some severe, to the Northeast and Mid-Atlantic, the Weather Channel’s Michael Palmer said.

“Large hail and damaging winds are the main threat with an isolated tornado possible.  Lingering warm and humid air ahead of the cold front will produce isolated severe storms in the Carolinas on Monday.”

Washington, D.C., was being hammered by showers and thunderstorms Sunday evening, which could go on until Monday morning, according to NBC Washington.

In Anderson County in upstate South Carolina citizens told authorities of possibly tornado sightings, according to County Administrator Rusty Burns. Burns said at least one hit was struck and had its roof torn up, but there were no reported injuries Sunday evening.

"Everything is under control now," Burns said.

There is also yet more bad news for the Plains: The chance of yet more severe storms returns Monday, Palmer said.

M. Alex Johnson, Janet Shamlian and Aaron Marmelstein of NBC News, and Mike Bettes of The Weather Channel, contributed to this report.

Related:

• Storm chaser caught in twister: It felt like I was going to heaven
• More Oklahoma twisters!? Latest outbreak fits Tornado Alley's pattern
• Midwest tornadoes like a giant game of Battleship

Slideshow: Tornadoes hit central Oklahoma

KFOR-TV

Click to view scenes from Friday's violent storm.

Launch slideshow

The death toll has jumped to 12 in the aftermath of a swarm of destructive twisters that tore through the Midwest, killing seven adults and two children in Oklahoma and causing three deaths in Missouri blamed on flooding.

Floodwaters also proved deadly in Oklahoma, where a 4-year-old girl died after she was swept away while taking shelter with her family in a ditch, according to police.

It is unclear whether the girl is one of the nine people who died as five tornadoes — one a half-mile wide — struck the Oklahoma City area Friday evening, terrorizing communities already battered by deadly storms this spring.

The Oklahoma Office of the Chief Medical Examiner told NBC News seven adults and two children are confirmed dead, including a mother and her small child. 

The medical examiner said that five of the nine dead had been positively identified and called on the public's help to identify the others. "If someone is missing a loved one from last night’s tornado, we would encourage them to contact our office at 405-239-7141," said Amy Elliott, of the medical examiner's office.

Hospitals in Oklahoma City reported 104 injuries, including five critical patients.

At least five people killed were in vehicles and may have been trying to flee as dark clouds gathered and warning sirens wailed, authorities said. 

Marcus Jolly, 32, of El Reno told The Oklahoman newspaper the scene along Interstate 40 "was a war zone. There were semis turned over and skeletons of buildings remaining.”

The twisters came just 11 days after a monster tornado left 24 dead in the Oklahoma City suburb of Moore, where power outages were reported Friday.

Mark Wiley, meteorologist at the National Weather Service’s southern region headquarters in Fort Worth, said early Saturday that there had been five confirmed tornadoes in the Oklahoma City area on Friday and one in the Tulsa area early Saturday.

A total of 12 tornadoes hit Missouri and Illinois around St. Louis, where “numerous homes” were damaged. Wiley did not have any information about casualties there. Two twisters touched down briefly in North Dakota, but did not do any damage.

The Oklahoma City area “definitely” experienced the worst of the bad weather, Wiley said, with wind gusts of up to 90 mph, baseball-sized hail and extensive flooding.

“We have several reports of water going into homes and dozens of people having to be rescued on the streets, especially along Interstate 40,” Wiley said. “It was not a good night to be in the Oklahoma City area.”

For Saturday, Wiley said the storm was moving toward Arkansas, Kentucky, Tennessee and East Texas, but did not “look as severe as yesterday.”

The worry now turns to flash flooding. Wiley said about 6 to 8 inches of rain had fallen in 12 hours between 7 p.m. Friday and 7 a.m. CT Saturday. The Weather Channel reported that May 2013 is the wettest May on record in Oklahoma City.

Friday, the terror came from tornadoes boasting baseball-sized hail and winds so strong they tossed tractor-trailers off the interstate. Meteorologists said the storm's fury didn't match that of the tornado that struck Moore on May 20 but dumped around 8 inches of rain on the area.

An SUV used by Weather Channel meteorologist Mike Bettes and a crew of storm trackers was thrown 200 yards by one tornado near Oklahoma City suburb El Reno. The vehicle tumbled about eight times and came to rest in a field, Bettes said. Some members of the crew suffered minor injuries, and the vehicle was destroyed.

"That was the scariest moment of my life," Bettes said. "I saw my life flash before my eyes."

Oklahoma Highway Patrol Trooper Betsy Randolph said the woman and baby were killed when the SUV they were in overturned on Interstate 40 between El Reno and Yukon.

Many of the injured were hurt in accidents along Interstates 35 and 40 west of the city, where at least three semi-trailer rigs were overturned after the biggest tornado touched down near El Reno, authorities said.

Bart Kuester, 50, a truck driver from Wisconsin, said he was driving along Interstate 35 past Moore when he realized a dangerous storm was approaching. 

"I heard the sirens going off and I could see it coming," he told The Associated Press. Kuester said the interstate was flooded and jammed with people trying to outrun the storm. 

"Everyone was leaving. ... Just because that one that hit Moore was so fresh in their memory," he said.

Authorities said some of the worst damage on Friday was from flooding around El Reno and Yukon and the danger continued into Saturday.

The National Weather Service issued flash flood warnings for parts of Oklahoma early Saturday.

There were also flash flood warnings in place for parts of Iowa, Illinois, Indiana, Missouri, Arkansas and  Kansas.

On Friday, one tornado turned south from Oklahoma City and then toward the suburb of Moore, which was hit by a devastating twister on May 20 that killed 24 people and injured hundreds of others.

“I think we are still a little shaken by what happened in Moore. We are still burying children and victims, so our emotions are still strong," Oklahoma City Mayor Mick Cornett told Reuters.

Gov. Mary Fallin declared a state of emergency.

"This has been a very large storm that hit a lot of communities," she told KFOR. She said she had heard from at least 30 fellow governors offering assistance.

At Will Rogers World Airport in Oklahoma City, where winds hit 71 mph, all flights were canceled and about 1,000 travelers were herded underground, where they were told to put their hands on their heads. The airport reopened Saturday morning, but all morning departures were canceled.

Tornado warnings — meaning a funnel cloud that could become a tornado had been spotted in the area — were in effect much of the day for numerous counties in Oklahoma, Missouri, Illinois and Wisconsin.

Forecasters sounded the alarm that much of the Midwest — already pummeled by a week of tornadoes and flooded with drenching rains — was facing another round of violent weather overnight and into the weekend.

Observers at Tinker Air Force Base reported a tornado on the ground near the base southwest of Oklahoma City. In Norman, home to the University of Oklahoma, a tornado touched down near Norman North High School and Norman Regional Hospital.

Buildings at Lambert-St. Louis International Airport were damaged by tornadoes with debris strewn across the runway. The airport was closed because of the damage, but re-opened just before midnight, the airport said in a statement.

Another tornado touched down Friday night 7 miles northeast of Moscow Mills, Mo., about 50 miles northwest of St. Louis. In St. Charles County, 24 houses were severely damaged or destroyed, said Mike O'Connell, communications director for the Missouri Department of Public Safety.

The National Weather Service evacuated its St. Louis office as tornado warnings were issued for north and northeastern St. Louis and surrounding counties.

Janet Shamlian and Aaron Marmelstein of NBC News, Mike Bettes of The Weather Channel, and Reuters contributed to this report. Follow M. Alex Johnson on Twitter and Facebook.

Related:

• More Oklahoma twisters!? Latest outbreak fits Tornado Alley's pattern
• Midwest tornadoes like a giant game of Battleship

As the American heartland continues to be hammered by a late but lethal tornado season, the U.S. East Coast is bracing for what could be another damaging and deadly hurricane season triggered by unusual climate conditions.

The 2013 Atlantic hurricane season, which officially begins Saturday, likely will be “above normal and possibly extremely active,” according to officials at the National Oceanic and Atmospheric Administration.

Meteorologists say the confluence of warm tropical waters and the slim chance of a cyclone-suppressing El Niño event may fuel three to six major hurricanes over the course of the summer, less than a year after Superstorm Sandy ravaged the mid-Atlantic region. Major hurricanes are defined as Category 3 or above.

Sandy was downgraded from hurricane status to tropical storm status just before it battered the northeast U.S. last October.

Gulf rigs stand ready as hurricane season arrives

Although meteorologists cannot say with certainty how many storms will hammer the coast – or where they will strike – there's a 96 percent chance of a hurricane hitting somewhere along the U.S. coast this summer, according to a forecast released in April.

“We really can’t say where the storms are going to go,” said Dr. Philip J. Klotzbach of the Tropical Meteorology Project at Colorado State University, who authored the forecast with his colleague Dr. William Gray. “But we know that more active seasons have more storms that make landfall.”

Above-average sea-surface temperatures create an environment that “will be very conducive for waves to develop and intensify” and potentially generate associated phenomena, such as increased moisture and lower air pressure, that foment giant storms, according to Klotzbach.

Water temperatures are expected to be 0.8 degrees Fahrenheit warmer than usual, according to The Associated Press.

Although an uptick of less than one degree "doesn't seem like a heck of a lot," Klotzbach said, "it makes a big difference in tropical waters."

What’s more, the unlikeliness of a significant El Niño event will make it easier for a cyclone to take shape, according to NOAA. El Niño is a vast stretch of unusually warm water in the Pacific Ocean that typically takes the edge off hurricanes.

“El Niño … is not expected to develop and suppress hurricane formation this hurricane season,” said Kathryn Sullivan, acting NOAA administrator.

NOAA forecasts 13 to 20 tropical storms, seven to 11 of which are projected to become hurricanes and three to six of which are projected to become major hurricanes.

Klotzbach's projection of four major hurricanes is in that range.

The last major hurricane to make landfall in the U.S. was Wilma in 2005, according to Klotzbach. Since then, five Category 1 or 2 storms – defined by winds moving as fast as 100 mph – have struck the U.S.

Atlantic hurricane season typically lasts for six months, usually peaking between late August and mid-October.

In the introduction to their forecast, Klotzbach and Gray warn coastal residents to take precautions in advance of storm season.

“Coastal residents are reminded that it only takes one hurricane making landfall to make it an active season for them, and they need to prepare the same for every season, regardless of how much or how little activity is predicted,” they wrote.

A day after deadly twisters tore through the Oklahoma City area for the second time in two weeks, forecasters say that a wide swath of the country – from the Ohio and Tennessee valleys to the Northeast – is under threat of heavy rainfall and fierce thunderstorms as the wild weather system moves eastward.

A cold front is expected to creep away from the Midwest and Plains states Saturday and inch toward to the east by Sunday, with heavy showers and severe thunderstorms projected to hammer a long belt of land, stretching from Maine to the Appalachians, according to The National Weather Service.

At least 40 million on the East Coast – including residents of Washington, D.C., Philadelphia, and New York City – should brace for the possibility of serious thunderstorms Sunday evening as the weather system cuts a path through the region, according to The Weather Channel.

All the while, flash flooding and river flooding are likely to remain a serious threat in the Midwest, particularly in Oklahoma, where at least five people were dead Saturday after multiple tornadoes ripped through the state just 11 days after a ferocious twister left 24 dead in the Oklahoma City suburb of Moore.

KFOR

A picture taken from a KFOR helicopter, which was heading to Logan County, Okla., where a possible tornado was forming. Logan County is about 20 miles north of Oklahoma City.

A group of severe thunderstorms spawned scattered tornadoes as it moved through Oklahoma and Arkansas on Thursday, with at least nine people injured in a storm system that cut a broad north-south swath across the central United States.

Storm spotters reported at least three Oklahoma tornadoes: a large twister in Broken Arrow outside Tulsa, another near Perkins and Ripley and a third northeast of Cove, according to the National Weather Service. Another tornado touched down near Oden, Ark.

Power lines were downed and the roofs of two businesses were damaged in Broken Arrow, but there were no immediate reports of injuries, emergency officials said.

Tornado watches for most of Eastern Oklahoma expired late Thursday, but parts of far eastern Oklahoma and northwestern Arkansas remained under a tornado watch until 4 a.m. Friday.

The National Weather Service issued tornado warnings for numerous counties across both states as the massive weather system heaved large balls of hail, producing heavy rain with possible significant flooding in several areas into Friday.

“To say the least, these storms have been menacing,” said Mike Bettes of The Weather Channel, who reported from Tulsa.

In Lawton, Okla., about 80 miles southwest of Oklahoma City, strong winds knocked down power poles and damaged at least a dozen homes, Comanche County's emergency agency reported. The Red Cross was assisting families who suffered damage.

The storm system also barreled through Arkansas, where a funnel cloud was reported in the small town of Oden. Two people who live on the west side of Oden were hurt when a tornado destroyed their home.

Residents in many other parts of the state were warned to seek shelter from possible tornadoes. 

In all, seven people were injured by tornadoes in Arkansas, according to The Associated Press. Two other injuries were attributed to lightning strikes. Lightning was also blamed for a fire at a residential complex in northwestern Indiana.

Severe weather was also possible for other states in the nation's midsection, including Kansas, Missouri, Iowa, Illinois, Wisconsin and Minnesota.

Early reports indicated that Thursday's tornadoes were much less severe than the EF-5 category storm that leveled parts of Moore, Okla., on May 20 and killed 24 people, including nine children. 

Meanwhile, the National Weather Service’s Albany, N.Y., office preliminarily confirmed that an EF-2 tornado with winds up to 125 mph touched down in Montgomery and Schenectady counties in upstate New York shortly before 7 p.m. on Wednesday.

More from weather.com

One person was reported to have been injured in the storm, which tore the roofs off many structures and damaged power lines and trees.

No details were immediately available on the injury.

Heavy rain and flooding is likely from the eastern Plains to the lower Great Lakes overnight, weather.com meteorologist Kevin Roth said. The storm system is forecast to move slowly eastward through the weekend.

Areas likely to be worst hit include Minneapolis, which is set for strong evening thunderstorms, and Kansas City, Roth said.

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This story was originally published on Thu May 30, 2013 4:23 PM EDT

More severe weather was forecast for the nation’s storm-battered midsection Thursday, including the threat of tornadoes in the Oklahoma City area hit by last week’s deadly twisters.

Heavy rain and flooding is likely from the eastern Plains to the lower Great Lakes, Weather Channel meteorologist Kevin Roth said.

Hail and damaging winds resulted in more than 250 storm reports by the end of Wednesday, according to weather.com, as a “multi-day severe weather outbreak” continued to bring misery to the Plains.

A preliminary 19 tornadoes were reported in four different states -- Texas, Kansas, Nebraska, and Iowa -- on Wednesday, weather.com said.

More from weather.com

At least 21 tornadoes touched down Tuesday, injuring at least seven people in three states.

The storm system responsible is forecast to move slowly eastward through the weekend, Roth said.

Areas likely to be worst hit include Minneapolis, which is set for strong evening thunderstorms, and Kansas City, Roth said.

In Oklahoma City, where 24 people were killed by twisters last week, severe storms are likely again Thursday evening, bringing the threat of more tornadoes.

Thursday’s storm system will reach the Northeast and Mid-Atlantic areas on Sunday, bringing showers, thunderstorms and cooler temperatures, Roth said.

Torrential rain and localized flooding is possible in parts of Florida over the coming days.

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A wide swath of the heartland – stretching from Texas to the Great Plains and up into the lower Great Lakes – was being threatened by monstrous thunderstorms Tuesday evening, kicking off what is expected to be a week of severe weather.

Tornado warnings were sent out in at least four states, with one massive twister already on the ground in Kansas – nearly one week after neighboring Oklahoma was devastated by a deadly twister.

Buildings in the town of Corning, Kan., were badly damaged Tuesday, but there were reportedly no injuries, according to Weather.com.

Flash flood warnings were issued for towns in northeast Kansas battered by as much as nine inches of rain, according to the National Weather Service.

Nebraska, Iowa, and Missouri were also bracing for dangerous conditions, including giant hail, fierce winds, and potential isolated tornados, the National Weather Service said.

Dirk Lammers / AP

Visitors watch as fast water crashes through the quartzite rocks at Falls Park in Sioux Falls, S.D., on Monday. Flash-flooding remains a threat Tuesday in some parts of the country.

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“The tornado threat seems highest from west-central Illinois west to Kansas, then southwest into west Oklahoma and northwest Texas,” Weather Channel meteorologist Kevin Roth warned.

Roth added that Oklahoma City - whose suburbs were devastated by tornadoes just over a week ago - was in the line of fire and could see more tornadoes Wednesday.

Meanwhile, thunderstorms producing 60 mph wind gusts and half-dollar-size hail bore down on parts of Colorado and Kansas on Tuesday morning, with the National Weather Service warning residents to take cover.

Parts of Interstate 70 in western Colorado were included in the warning area.

Those warnings came just an hour after nearly identical forecasts for parts of Missouri, with the weather service office in St. Louis saying damage to vehicles, crops, trees and housing exteriors was expected.

A flash-flood watch was in effect for northeast and central Missouri and parts of central Illinois, and a flood warning was issued for the La Moine River at Ripley, Mo.

Slideshow: Tornadoes ravage Plains

Tom Pennington / Getty Images

A monster tornado hit Moore, Okla., Monday afternoon, leaving at least 24 dead.

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The storm threat was predicted to continue through the week, with severe storms likely Wednesday and Thursday across the Plains and upper Midwest, Roth said.

The potential for dangerous tornadoes is considered highest on Wednesday from southeastern Nebraska to north-central Texas.

Then on Thursday, tornado outbreaks are likely from the upper Mississippi Valley and eastern Dakotas south to central Oklahoma, Roth said.

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• Third victim found in Texas flooding
• More weather coverage from NBCNews.com

This story was originally published on Tue May 28, 2013 6:47 AM EDT

The first three days of the week bring the possibility of tornadoes, forecasters said, but the biggest threat is on Wednesday.

The National Weather Service on Monday issued tornado warnings and severe thunderstorm watches for parts of Kansas and Nebraska that remain in effect until 1 a.m. ET. Several tornadoes were reported to the National Weather Service throughout the day in Nebraska, Colorado and Wyoming, but none are believed to have caused any damage.

On Tuesday, storms packing heavy rainfall will bring the possibility of large hail, dangerous wind gusts and tornadoes to the
central U.S., according to Weather Channel meteorologist Greg Forbes.

“A tornado outbreak is possible over the central part of the U.S. in the traditional Tornado Ally area,” said Forbes.

The predictions for potentially devastating storms follow a Memorial Day weekend full of wild weather. Three people died in powerful floods in the San Antonio, Texas, area over the weekend. Some 130 people had to be rescued during a storm that dumped more
than a foot of rain on the city in just 24 hours. Cars and a city bus were swept off the streets.

And though the start of June is less than a week away, parts of upstate New York and Vermont were buried under as much as 34 inches of snow, according to weather.com. The heavy snow brought down trees and power lines.

Temperatures in the snow-laced areas are expected to return to levels more typical of late May in coming days.

Though many throughout the country were disappointed that the weekend known as the unofficial start to summer was colder than usual, those in the Northeast will not have to wait long for things to heat up.

According to the National Weather Service, "A big warm front is forecast to lift northeast through the Ohio Valley by Wednesday afternoon."  Those from Boston to Washington, D.C., will experience summer-like temperatures that may reach up to 90 degrees come
Friday. 

This story was originally published on Mon May 27, 2013 5:00 AM EDT