# data[].attributes.attachment_link.readable_text
Rain & Floods

How does rain form?
Water droplets form from warm air. As the warm air rises in the sky it cools. Water vapor (invisible water in the air) always exists in our air. Warm air holds quite a bit of water. For example, in the summer it is usually very humid. When enough of these droplets collect together, we see them as clouds. If the clouds are big enough and have enough water droplets, the droplets bang together and form even bigger drops. When the drops get heavy, they fall because of gravity, and you see and feel rain.

What causes rain?

When clouds develop or rain occurs, something is making the air rise. Several things can make this happen. Mountains, low-pressure areas, cold fronts, and even the jet stream.

How big are raindrops?
Raindrops are much smaller than we think! They are actually smaller than a centimeter. Raindrops range from 1/100 inch (.0254 centimeter) to 1/4 inch (.635 centimeter) in diameter.

How fast do raindrops fall?
Not including wind-driven rain, raindrops fall between 7 and 18 miles per hour (3 and 8 meters per second) in still air. The range in speed depends on the the size of the raindrop. Air friction breaks up raindrops when they exceed 18 miles per hour.

What is a flood?
A flood results from days of heavy rain and/or melting snows, when rivers rise and go over their banks.

What is a flash flood?
A flash flood is sudden flooding that occurs when floodwaters rise rapidly with no warning within several hours of an intense rain. They often occur after intense rainfall from slow moving thunderstorms. In narrow canyons and valleys, floodwaters flow faster than on flatter ground and can be quite destructive.

Do flash floods hurt people?
Flash floods are the #1 weather-related killer in the U.S. Nearly 80% of flash flood deaths are auto related. Know beforehand if your area is a flood risk.

How much water is needed for your car to float away?
A mere 2 feet of water can float a large vehicle or even a bus. This is why you should never drive through flooded roads. Just 6 inches of rapidly moving flood water can knock a person down.

What is a monsoon?
A monsoon is a seasonal wind, found especially in Asia that reverses direction between summer and winter and often brings heavy rains. In the summer, a high pressure area lies over the Indian Ocean while a low exists over the Asian continent. The air masses move from the high pressure over the ocean to the low over the continent, bringing moisture-laden air to south Asia. During winter, the process is reversed and a low sits over the Indian Ocean while a high lies over the Tibetan plateau so air flows down the Himalaya and south to the ocean. The migration of trade winds and westerlies also contributes to the monsoons. Smaller monsoons take place in equatorial Africa, northern Australia, and, to a lesser extent, in the southwestern United States.

What is radar?
Radar is an electronic instrument, which determines the direction and distance of objects that reflect radio energy back to the radar site. It stands for Radio Detection and Ranging. This is what meteorologists use to see rain or snow.

What is Doppler Radar? Doppler Radar detects precipitation intensity, wind direction and speed, and provides estimates of hail size and rainfall amounts. Doppler Radar gives forecasters the capability of providing early detection of severe thunderstorms that may bring strong damaging winds, large hail, heavy rain, and possibly tornadoes. Combined with satellites, radar gives forecasters the ultimate tools to provide accurate forecasts and advanced severe weather warnings.

Doppler Radar gets its name from the Doppler Effect. Have you ever listened to a train whistle as it was coming toward you? You probably noticed that the pitch of the whistle changed as the train passed you and moved away. This change in the frequency of sound is called the Doppler Effect. Doppler Radar measures the changes in the frequency of the signal it receives to determine the wind. How does Doppler Radar work?

The National Weather Service has installed a new type of Doppler Radar called NEXRAD Radar. NEXRAD stands for Next Generation Radar. This radar produces many different views of storms and rain that allows meteorologists to determine if a storm could be severe.
What is NEXRAD Radar?

Know the Lingo

FLOOD WATCH - means that an overflow of water from a river is possible for your area.

FLASH FLOOD WATCH - means that flash flooding is possible in or close to the watch area. Flash Flood Watches can be put into effect for as long as 12 hours, while heavy rains move into and across the area.

FLOOD WARNING - means flooding conditions are actually occurring in the warning area.

FLASH FLOOD WARNING - means that flash flooding is actually occurring in the warning area. A warning can also be issued as a result of torrential rains, a dam failure or snow thaw.
Click Here to see if there are any active warnings in your area.
Flood Safety Tips

BEFORE A FLOOD: Have a disaster plan and prepare a disaster supplies kit for your home and car. Include a first aid kit, canned food, can opener, bottled water, battery-operated radio, flashlight, protective clothing and written instructions on how to turn off electricity, gas, and water.
DURING A FLOOD: Move to a safe area quickly. Move to higher ground, like the highest floor of your home. Avoid areas subject to sudden flooding like low spots and canyons. Avoid already flooded areas. If a flowing stream of water is above your ankles stop, turn around and go the other way. Do not attempt to drive through a flooded road. The depth of the water is not obvious and the road may be washed away. If your car stalls, leave it and seek higher ground. Rapidly rising water may engulf the car, pick it up and sweep it away. Kids should never play around high water, storm drains or viaducts. Be cautious at night, because its harder to see flood dangers. If told to evacuate, do so immediately.
AFTER THE FLOOD: Always, boil drinking water. Electrical equipment should be checked and dried before used.
Rain Activities

Lesson Plan: Here is a great lesson plan on learning about precipitation. In this activity, kids will use a weather map to answer questions about precipitation falling across the country. Note: This is a PDF file, so you need to have Adobe Acrobat Reader.

Pressure Experiment: Here is an experiment that shows how pressure is created in our atmosphere by sucking an egg in a bottle. This is a very cool experiment!

Science Fair Project Ideas: Here is a complete list of science fair project ideas. Discover the science behind the weather that impacts us every day.Make A Barometer Experiment: Here is an experiment that allows the kids to make a barometer.

Evaporation Experiment: Here is an experiment that shows kids how evaporation takes place.

# data[].attributes.attachment_link.title
Weather Wiz Kids weather information for kids

# data[].attributes.attachment_link.description
Weather Wiz Kids is a fun and safe website for kids about all the weather info they need to know. It contains tools for weather education, including weather games, activities, experiments, photos, a glossary and educational teaching materials for the classroom.

# data[].attributes.attachment_link.readable_text
Floods, among the most terrifying forces on Earth, have led to countless disasters throughout history. The story of a catastrophic flood -- a metaphor for a cleansing of humanity's sins -- appears in many cultures, from ancient Mesopotamia to China, to Maya peoples and aboriginal tribes in Australia.

Flooding killed 116 people in the United States last year, the most lethal type of weather event in the nation. Floods also are responsible for about $6 billion in damage annually in this country, according to National Geographic.

Much of the severe flooding in America has occurred around the Mississippi River and in Texas, as well as along the Gulf Coast and Florida, because those areas are vulnerable to hurricanes.

Floods have shaped the history of our nation, wiping out some communities forever, and forcing others to start a new life in another part of the country.

In June, the Weather Network forecast normal or above normal rainfall east of the Mississippi River and in the southwest this summer. With that prediction, and with it fears of disastrous flooding that accompany hurricane season, 24/7 Wall Street has created a list of the 30 worst floods in our nation's history. We used data compiled by government agencies, including the National Weather Service, and consulted sources such as media accounts of historical weather events to develop this list.

More: Which state is America's most miserable? An analysis of well-being

30. Hurricane Harvey

Houston missed the brunt of the impact of Hurricane Rita in 2005, but it was not so fortunate with Hurricane Harvey. That tempest caused widespread devastation in the greater Houston area. The slow movement of Harvey from Aug. 26-30 contributed to the destructive and deadly floods in southeast Texas. The most rain fell in Nederland, Texas, which received more than 60 inches of rain from Aug. 24-Sept.1. The flooding in the region displaced 30,000 people and damaged or destroyed more than 200,000 homes and businesses.

29. Los Angeles flood

After a few years of dry weather, Los Angeles received five days of rain from two storms starting on Feb. 27, 1938. Excessive rainfall caused the Los Angeles, San Gabriel, and Santa Ana rivers to overflow. Bridges, roads, and buildings were wiped out; phone lines were downed; and whole communities were cut off. The destruction from the flood prompted the city to rethink zoning and planning decisions that led to the creation of today's Los Angeles.

28. Buffalo Creek flood

West Virginia has been witness to many mining disasters, but this one occurred above ground, not below. On Feb. 26, 1972, a coal waste dam -- constructed to hold water, coal waste, and silt -- collapsed, releasing 132 million gallons of black ooze into a narrow valley. The wall of water was reportedly up to 20 feet high. The onslaught wiped out 17 communities downstream. Some towns were rebuilt but others vanished. State and federal investigations determined that the dam, owned and operated by the Buffalo Mining Company, was not built properly and that the mining company's parent, The Pittston Company, had disregarded the safety of the residents. Survivors and family victims sued Pittson, and in 1974, the suit was settled for $13.5 million, or an average of $13,000 per plaintiff after legal fees.

27. Hurricane Agnes flood

1972 was a bad year for bad weather events. That year, Hurricane Agnes, one of the largest ever recorded in June, brought torrential rain to a wide swath of the eastern United States on June 19. The storm swept up 15 states in its wake. The worst impact from flooding was in Pennsylvania, where the Susquehanna and Lackawanna rivers caused significant damage to the Wilkes-Barre-Scranton metropolitan area. Even Pennsylvania's governor had to be rescued from the governor's mansion in Harrisburg. At the time, Agnes was the costliest hurricane in U.S. history.

26. Southeast U.S. floods

The southeastern part of the United States was torn asunder by tornadoes and floods that cost the lives of 132 people. Property damage surpassed the $1 billion level. El Nino was blamed for the unstable weather, which began in the winter of 1997 and went into spring of the following year. During that winter, Florida received above-average rainfall, causing extensive flooding. In Tampa, 36 inches of rain fell that winter.

More: US population changes: What's the fastest shrinking county in your state?

25. Mill River Dam

The failure of the Mill River Dam in Massachusetts, a major disaster in the late 19th century, is an example of an avoidable tragedy. The reservoir dam was built in the hills above Williamsburg and Northampton in western Massachusetts. It burst during the early hours of May 16, 1874, and water cascaded down a narrow valley of factories and farms. About 600 million gallons of water flooded the area, rising to 40 feet. An hour later, 139 people were dead. Investigations revealed that the dam was poorly built, but no one was held accountable. The tragedy prompted residents in western Massachusetts to adopt stricter safety measures for reservoir dams.

24. Big Thompson Canyon Flood

The Big Thompson Canyon Flood marred the centennial celebration of Colorado becoming a state. Party-goers had gathered in the canyon on July 31 to celebrate the centennial. In late afternoon, a light rain began to fall. It turned heavy in early evening. In a two-hour span that evening, a year's worth of rain fell in the region. Water cascaded down mountainsides. At 10:30 p.m., a massive wave of water 20 feet high roared through the canyon, washing over everything ahead of it. Helicopters were deployed to find the 144 victims of the flood.

23. Pacific tsunami

The Aleutian Islands earthquake launched a tsunami on April 1, 1946, that overwhelmed parts of Alaska and Hawaii. Unimak Island in the Aleutian island chain was first hit by a 100-foot wave that wiped out a lighthouse 30 feet above sea level, killing five people. The wave headed south to Hawaii where it slammed into Hilo, erasing a third of the city. A schoolhouse in another part of the island state was destroyed, killing a teacher and 25 students.

22. Brazos River Flood

The Brazos River Basin was familiar with periodic flooding, which helped cotton farmers grow their crop. Still, area residents were not prepared for what happened on Dec. 5, 1913. Heavy rain began falling on already elevated river water levels, and water overflowed the riverbank and washed into East Waco. Two people were killed by the surging river, and businesses were damaged. Farther south, the Brazos River and Colorado River overflowed their banks and combined, the deluge eventually killed 177 people. The flood prompted action to protect the city of Waco from further flooding.

21. Floods in eastern U.S.

Blizzards are bad enough, but when a heavy volume of snow melts causing flooding, that is a deadly one-two punch. Such was the case in early 1996, when that combination overwhelmed many states in the eastern United States. The Susquehanna River overflowed its banks and flooded low-lying areas. More than 3 inches of rain fell in 24 hours at Williamsport, Pennsylvania. That rainfall led to some of the worst flooding in the Keystone State since Hurricane Agnes 24 years earlier.

More: What city is hit hardest by extreme poverty in your state?

20. East Coast floods

Back-to-back hurricanes led to extensive floods on the East Coast in August 1955. At the time, Hurricane Diane, the second of the two storms to strike the region, was the costliest storm on record. The heaviest rain fell in northern Virginia, with more than 5 inches inundating the region in 24 hours. More than 200 dams In New England either partially or completely failed.

19. Great Northeast Flood

The massive flood that engulfed half of the eastern United States, almost biblical in scope, started with snowmelt, then a downpour, on March 11 that did not relent for 14 days. The tiny town of Pinkham Notch recorded rainfall of more than 22 inches over the period. Rivers throughout New England states overflowed. At the Vernon Dam in Vermont, flood waters from the Connecticut River rose 19 feet above the dam. About 200 people lost their lives, and 14,000 were made homeless. Because of the disaster, Congress passed the Flood Control Act of 1936, which President Franklin Roosevelt then signed. The act empowered the Army Corps of Engineers to build levees, flood walls, and reservoirs.

18. Texas flood

The rainstorm in Texas in 1921 is considered the greatest such event in the history of the Lone Star State. The storm entered the region as a hurricane in Mexico and brought torrential rain in Texas as it moved in a northeasterly direction. In its path, 215 people were killed. The rainfall left up to 9 feet of water in downtown San Antonio. In the town of Taylor, almost 24 inches of rain fell in 35 hours as measured at the U.S. Weather Bureau station on Sept. 9-10.

17. Superstorm Sandy

By the time Sandy reached the New York metropolitan area on Oct. 29, 2012, it had been downgraded to a superstorm from a hurricane. Yet it would turn out to be one of the costliest weather events in U.S. history. Subway service in New York City was knocked out, and multi-million-dollar homes at the Jersey Shore were destroyed. The destructive force of the storm and loss of life ratched up the urgency level for preparing shoreline defenses along the New Jersey coast as well as New York City to address the reality that stronger storms are in the region's future because of climate change.

More: Historic blunders: 50 worst product flops of all time

16. Black Hills Flood

Heavy thunderstorms struck the Rapid City region of South Dakota on June 9, 1972, and because of strong easterly winds, the storm system stayed over the area. Flood water from various creeks emptied into Rapid Creek, swelling that body of water to more than 300 times its regular volume. According to the NWS, data from the stream meter on Rapid Creek above Canyon Lake showed that in a two-hour span the water level climbed 12 feet. The dam at Canyon Lake failed, and water rushed through Rapid City and the eastern foothills of the Black Hills.

15. Mississippi flood

People living along the Mississippi River know it floods often -- and they have learned to live with it. But no one was ready for what historians called one of the greatest peacetime disasters in U.S. history in April 1927. The Great Mississippi River Flood engulfed 16 million acres and displaced about 640,000 people from Illinois to Louisiana. In Vicksburg, Mississippi, the river swelled to 80 miles wide.

There were other consequences from the deluge. African Americans living in the flood zone were forced to leave their homes in the South, and the flood hastened what would become known as the Great Migration to northern cities as African Americans sought a better life.

More: Per capita government spending: How much does your state spend on you?

14. Hurricane Camille and flooding

Hurricane Camille was a category 5 hurricane that slammed into the Gulf Coast of Mississippi on Aug. 17, 1969 and brought tremendous storm surge to the region. A storm tide of greater than 24 feet overflowed the town of Pass Christian, Mississippi. At the time, storm surges along that area of the Gulf Coast were the highest ever recorded in the United States. In addition to the 256 people who were killed, 20,000 were left homeless, and thousands of farm and domestic animals were drowned.

13. Brazos River flood

Rain fell on the Brazos River region for 11 straight days beginning June 17, 1899. Rainfall totals reached almost 9 inches that week across 66,000 square miles of Texas. The Brazos River overflowed its banks and flooded the surrounding area for 12,000 square miles. In July, flood waters would rise over 58 feet in the town of Richmond. It wouldn't be the last flood-related tragedy to befall the region.

12. Oregon Heppner flash flood

A brief, hard rain and hail in the Blue Mountains triggered a sudden and deadly flash flood through Heppner, Oregon, on June 14, 1903, drowning 324 people. Waters rose up to 40 feet high and saturated the town. The death toll would have been much higher, but towns in the path of those waters were warned ahead of time and residents were able to evacuate. It's unclear exactly how much rain fell during the disaster because the local weather station was destroyed in the flood.

11. Miami hurricane and flooding

It was bad enough that the Florida real estate market had collapsed in the mid-1920s, but then one of the worst storms ever blasted Florida and the Atlantic Coast on Sept. 18, 1926. The tempest brought deadly storm surge and flooding to the hurricane-prone area. A tidal wave swept over Miami Beach and Biscayne Bay, and boats were scattered all over the city. The storm left 372 people dead and up to 6,000 injured. There had been some advance warning of the approaching hurricane from reports from ships in the area, but in 1926, few people had radios and there were few methods to pass along the warning to the population. Property damage was the highest in U.S. history to that point.

10. The Ohio River Flood

How bad was the Ohio River Flood in 1937? The NWS said the deluge "surpassed all previous floods during the 175 years of civilized occupancy of the lower Ohio Valley." The flood started in late January 1937 and was bolstered by record rainfall in river cities such as Louisville, Kentucky (20 inches); Evansville, Indiana (15 inches); and Cincinnati, Ohio (14 inches). The NWS said 70% of Louisville was under water. The Cincinnati Enquirer reported that one-fifth of Cincinnati was under water. The nightmare got worse -- as the water rose, gas tanks exploded and oil fires ignited along the river.

More: Can you afford that new vehicle? 25 most expensive car models to insure

9. Labor Day Hurricane

The 1920s were a difficult time to live in Florida because of the real estate collapse and severe weather events, and the Labor Day Hurricane of 1935 brought even more misery to the Sunshine State. The category 5 tempest devastated the Florida Keys, producing a storm surge of up to 20 feet above sea level. The railroad connecting the Keys to the mainland was destroyed. Among the scores who died were World War I veterans who were building a highway and living in federal rehabilitation camps. After the storm, Ernest Hemingway traveled to the Keys to help with the recovery. What he saw prompted him to write a scathing magazine article titled "Who Killed the Vets?"

8. St. Francis Dam failure

The St. Francis Dam failure was the second-worst disaster in California's history after the San Francisco Earthquake and among the greatest dam catastrophes in the U.S. history. Built in 1926, the dam was the creation of self-taught civil engineer William Mulholland. The 1,300-foot dam held more than 12 billion gallons of water, enough to supply Los Angeles for a year. But there were integrity issues of the dam from the beginning. On the morning of March 12, 1928, the dam keeper noticed muddy leaks emerging from the dam. He summoned Mulholland and his chief assistant, who inspected the dam and said it was safe. Twelve hours later, the dam keeper and his 6-year-old son would be the first drowning victims after the dam gave way. The wall of water would surge 54 miles until it reached the Pacific Ocean.

7. Statewide Ohio flood

The worst weather event in Ohio history occurred in late March 1913, killing 467 people and flooding 40,000 homes. Excessive rainfall all over the state caused the flood. In Dayton, swiftly flowing water as deep as 10 feet deep swept through downtown streets, killing 123 people. Downstream on the Miami River, 100 more people died in Hamilton, where water rose to as much as 18 feet deep. Another 100 people died in Columbus, where survivors were plucked from trees and rooftops. At Cincinnati, the Ohio River rose 21 feet in 24 hours. Hoping to avoid a repeat of the calamity, flood control reservoirs were established by the Miami Conservancy District after the flood of 1913.

More: Thinking of buying an inexpensive vehicle? 25 cheapest car models to insure

6. New England hurricane and flooding

On Sept. 21, 1938, one of the most famous nor'easters of all time destroyed much of eastern Long Island before it unleashed its wrath on New England. It was a fast-moving storm that the NWS said was moving at 47 mph, and it produced up to 7 inches of rainfall. Tidal waves at least 50 feet high, as recorded in Gloucester, Massachusetts, overwhelmed unprotected beaches, and the deluge turned cottages into matchsticks. The region's deadliest disaster claimed at least 700 lives, and 2,000 others were injured. More than 63,000 people were made homeless. Almost 20,000 buildings were destroyed, and 100 bridges had to be reconstructed.

5. Hurricane Katrina flooding

Part of the tragedy of Katrina is tied to how humans have altered the landscape around New Orleans. New Orleans was once above sea level when French settlers first arrived there 300 years ago, but swamp drainage has caused the city to sink. The areas below sea level, those most at risk to flooding, have generally been home to the city's poorest residents. What's more, New Orleans relied on a system of levees and seawalls built by the Army Corps of Engineers to keep the city from flooding. But when Katrina hit on Aug. 29, 2005, the levees failed. As a result, 80% of the city flooded. It was the costliest hurricane in U.S. history.

4. South Carolina Sea Islands hurricane

In the late 19th century, people lacked the kind of weather prediction and warning system we have today. It was for this reason that South Carolina, and in particular the Sea Islands that form a barrier along the state coastline, were caught unawares by a hurricane on Aug. 27, 1893. The hurricane swept through the sea islands near Savannah, leaving more than 2,000 dead. Most died by drowning. Nearly every building on the Sea Islands was destroyed, and 30,000 people became homeless.

3. Johnstown flood

On May 31, 1889, following several days of heavy rain, a dam near Johnstown burst. The size and scope of the flood that ensued is difficult to comprehend even today. Up to 2,209 people died, including 99 entire families. Bodies were found as far away as Cincinnati. Flood lines were marked as high as 89 feet above river level, and the wave that struck Johnstown was said to be 40 feet high. The South Fork Fishing and Hunting Club, whose members included industrialists Andrew Carnegie and Henry Clay Frick, owned the dam but managed to avoid liability. Historians and legal experts believe the anger over the failure to find fault in the tragedy led to stricter liability laws in the United States. It was the first major disaster in which the American Red Cross was involved.

More: Who is drinking the most? The drunkest (and driest) cities in America

2. South Florida hurricane and flood

Barely two years after absorbing the impact of a hurricane that ravaged Miami, Florida was whipsawed by another tempest in late September 1928 -- a storm that cost the lives of more people in that state than any other natural weather event. On the southern shore of Lake Okeechobee, about 6,000 people lived in a farming community, and nearly half would perish from the storm. A 5-foot mud dike constructed to hold back Lake Okeechobee gave way, letting loose a tidal wave. There were so many people killed so quickly, and the bodies decomposed so rapidly because of the heat, that the survivors had to burn the corpses. More than 600 of the dead were African Americans who were buried in unmarked graves in a West Palm Beach pauper cemetery.

1. Galveston hurricane and storm surge

The Galveston Hurricane of 1900 is the deadliest natural disaster in U.S. history. It's believed that 8,000 people were killed in the high winds, 15-foot storm surge, and flooding brought on by the category 4 hurricane. But the actual number could be as many as 12,000 people.

Though the storm was powerful, many of the casualties could have been avoided. The Weather Bureau, which became the National Weather Service, predicted the storm would land much further east. Warnings from Cuba about the storm were ignored by residents and many vacationers, and the city was largely unprepared for the hurricane that slammed into it on Sept. 8, 1900. Galveston was once a booming port city, but the destruction of the hurricane was too much for the city to fully recover from as investors began to favor Houston instead.

More: Population migration patterns: US cities Americans are abandoning

Detailed findings

There are three categories of floods: flash flooding, river flooding, and coastal flooding.

The most lethal of these are flash floods, such as the one that occurred in 1972 in South Dakota that claimed 238 lives. The factors that contribute to flash floods are rainfall intensity and duration. Topography also plays a role -- if the soil is too sodden with moisture, it may not be able to absorb rainfall. Flash flooding also can lead to mudslides, particularly in western states. Steep ravines and canyons can funnel high volumes of water, exacerbating flood intensity, as was the case in Colorado in 1976 in Big Thompson Canyon.

Other reasons for flash flooding are the rupture of a dam, slow-moving storms, or a surge of water released from an ice jam.

Some of the most severe flooding in our nation's history, such as the disastrous event in 1927, occurred in areas around the Mississippi River. Hurricanes that have ravaged Florida and the Gulf Coast have brought with them storm surges that caused record damage in Louisiana in 2005 with Hurricane Katrina and in Texas just last year with Hurricane Harvey.

Climate change has raised concerns of increased flooding and the impact that flooding from rising sea levels will have on those living on American coasts. Climatologists are concerned that melting snowfields and polar ice caps will cause more runoff and severe weather events, such as storm surges and coastal and river floods.

In some of these catastrophic flood events, human error, neglect, or miscalculation contributed to the scale of the disaster. In the case of the St. Francis Dam in Los Angeles in 1928, structural defects in the dam led to its collapse just two years after it was completed. At least 400 people were killed from the ensuing flood, and the calamity is the second greatest disaster in California history.
Methodology
The good news is that humankind has become better at understanding the dynamics behind floods, and the use of advanced weather forecasting and satellite tracking can provide early warning. Evacuations ahead of recent hurricanes in Louisiana and Texas helped save lives.
24/7 Wall Street is a USA TODAY content partner offering financial news and commentary. Its content is produced independently of USA TODAY.
24/7 Wall Street compiled a list of the worst floods in U.S. history by the number of fatalities. Floods occur for various reasons -- dams bursting, intense rainfall, massive water runoff from snowmelt, storm surge from hurricanes, even impact from tornadoes. In order to capture the scope of these tragic historical chapters in our nation's history, we tried to include any and all weather-related events that could have contributed to floods. 24/7 Wall St. used government sources such as the National Weather Service Weather Forecast Office, The National Oceanic and Atmospheric Administration, and the United States Geological Survey as well as media reports about the flood events to create the list of the worst floods in U.S. history. Cost of damage was rendered in inflation-adjusted dollars.

# data[].attributes.attachment_link.title
What are the worst floods in American history? A rundown of the top 30

# data[].attributes.attachment_link.description
24/7 Wall Street has created a list of the 30 worst floods in our nation's history. We used data compiled by government agencies, including the National Weather Service, and consulted sources such as media accounts of historical weather events to develop this list.

# data[].attributes.attachment_link.readable_text
Floods may:

Find safe shelter right away.

Do not walk, swim or drive through flood waters. Turn Around, Don't Drown!

Remember, just six inches of moving water can knock you down, and one foot of moving water can sweep your vehicle away.

Stay off bridges over fast-moving water.

Depending on the type of flooding:

Evacuate if told to do so.

Move to higher ground or a higher floor.

Stay where you are.

Preparing for a Flood
Make a plan for your household, including your pets, so that you and your family know what to do, where to go, and what you will need to protect yourselves from flooding. Learn and practice evacuation routes, shelter plans, and flash flood response. Gather supplies, including non-perishable foods, cleaning supplies, and water for several days, in case you must leave immediately or if services are cut off in your area.

In Case of Emergency
Keep important documents in a waterproof container. Create password-protected digital copies. Protect your property. Move valuables to higher levels. Declutter drains and gutters. Install check valves. Consider a sump pump with a battery.

Evacuate immediately, if told to evacuate. Never drive around barricades. Local responders use them to safely direct traffic out of flooded areas.

Contact your healthcare provider If you are sick and need medical attention. Wait for further care instructions and shelter in place, if possible. If you are experiencing a medical emergency, call 9-1-1.

Listen to EAS, NOAA Weather Radio or local alerting systems for current emergency information and instructions regarding flooding.

Do not walk, swim or drive through flood waters. Turn Around. Don't Drown!

Stay off bridges over fast-moving water. Fast-moving water can wash bridges away without warning.

Stay inside your car if it is trapped in rapidly moving water. Get on the roof if water is rising inside the car.

Get to the highest level if trapped in a building. Only get on the roof if necessary and once there signal for help. Do not climb into a closed attic to avoid getting trapped by rising floodwater.

Pay attention to authorities for information and instructions. Return home only when authorities say it is safe.

Avoid driving except in emergencies.

Wear heavy work gloves, protective clothing and boots during clean up and use appropriate face coverings or masks if cleaning mold or other debris.

People with asthma and other lung conditions and/or immune suppression should not enter buildings with indoor water leaks or mold growth that can be seen or smelled. Children should not take part in disaster cleanup work.

Be aware that snakes and other animals may be in your house.

Be aware of the risk of electrocution. Do not touch electrical equipment if it is wet or if you are standing in water. Turn off the electricity to prevent electric shock if it is safe to do so.

Avoid wading in floodwater, which can be contaminated and contain dangerous debris. Underground or downed power lines can also electrically charge the water.

Use a generator or other gasoline-powered machinery ONLY outdoors and away from windows.

# data[].attributes.attachment_link.description
Floods are the most common natural disaster in the United States. Learn how to stay safe when a flood threatens. Prepare for a flood During a flood After a flood Associated content Flooding is a temporary overflow of water onto land that is normally dry. Floods are the most common disaster in the United States.

# data[].attributes.attachment_link.description
Floods often destroy homes and devastate crops and wildlife habitat. Severe floods can even kill people and animals. Floods also have benefits: they replenish groundwater and enrich soil.

# data[].attributes.attachment_link.title
Newsela | Forced budget cuts could hurt crucial U.S. flood warning system

# data[].attributes.attachment_link.description
Spring is off to a deadly start in the Midwest, where floodwaters have killed at least four people and driven thousands from their homes.