Learn more about how hurricanes form. Florence dropped nearly 36 inches of rain in Elizabethtown, North Carolina, and led to widespread flooding throughout the Carolinas. Credit: NOAA. Another phenomenon that can cause extreme rainfall is called an atmospheric river. Atmospheric rivers are long, narrow conveyor belts of moisture that move through the atmosphere.
Strong atmospheric rivers can deliver enormous amounts of rain and snow in California, the Pacific Northwest and Alaska, especially during the winter months.
This can lead to serious flooding and mudslides. The ABI can also determine the amount of total moisture in the atmosphere from the ground all the way to the top of the atmosphere. This provides useful information for weather forecasters to improve predictions for heavy rains and flash flooding and help people stay safe. After flooding occurs, weather satellites can also be used to spot heavily flooded regions from space.
This flood map shows the impact of Hurricane Irma in Florida on Sept. Colors correspond to the fraction of land covered by water, ranging from green less than 30 percent to red more than 90 percent. According to our friends at the National Severe Storms Laboratory , there are five types of floods. They include:. River Flood. Coastal Flood. Storm Surge.
Inland Flooding. Flash Flood. As you can infer from the list above, flooding can happen anywhere, including both coastal and inland locations. The first type of flooding we will explore is river flooding. A river flood occurs when water levels rise over the top of river banks. This flooding can happen in all river and stream channels.
Causes of River Flooding. River flooding typically happens for four reasons. They are:. Excessive rain from tropical storm systems making landfall. Persistent thunderstorms over the same area for extended periods. Combined rainfall and snowmelt. Ice jam. More on Riverine Floods. River floods can happen suddenly or slowly. Sudden river flooding events occur more often on smaller rivers, rivers with steep valleys, rivers that flow for much of their length over impermeable terrain, and normally dry channels.
On the other hand, low-rising river floods typically occur in large rivers with large catchment areas. The next type of flood you should know about is a coastal flood. What is Coastal Flooding? A coastal flood is the inundation of normally dry land areas along the coast with seawater. Causes of Coastal Flooding. Coastal flooding is typically a result of a combination of sea tidal surges, high winds, and barometric pressure. These conditions typically come from storms at sea like:.
Tropical cyclones. Higher-than-average tides. Another type of flooding that is often associated with coastal flooding is storm surge. What is Storm Surge? Storm surge is an abnormal rise in water level in coastal areas over and above the regular astronomical tide. Causes of Storm Surge. Storm surge is always a result meteorological storms that cause higher than normal tides on the coast. There are three parts of a storm that create this surge.
Low atmospheric pressure. Learn about storm surge from one of our expert meteorologists, Andrew Rosenthal in the below snippet from our weather safety warmup webinar on hurricanes :. Storm surge is an extremely dangerous form of flooding. It can flood large coastal areas at the same time.
It can also cause flooding very quickly. Extreme flooding occurs when storm surge happens at the same time as high tide.
This can cause storm tides to reach over 2o feet! Our meteorologists always stress that storm surge is the most dangerous aspect of any tropical system.
It poses the most threat to both life and property. For example, storm surge took the lives directly and indirectly of over 1, people during Hurricane Katrina. The next type of flood on our list is an inland flood. Some organizations refer to inland flooding as urban flooding. A flash flood is also a type of inland flood. What is an Inland Flood? An inland flood is flooding that occurs inland or not in a coastal area. Therefore, coastal flooding and storm surge are not inland floods.
Causes of Inland Flooding. Rainfall is almost always to blame for inland floods. Rain causes inland flooding in two ways.
It can happen with steady rainfall over several days or it can happen because of a short and intense period of rainfall. Snowmelt also causes inland floods, although rainfall is a more common cause. Another way inland flooding happens is when water ways get blocked by debris, ice, or dams.
More on Inland Floods. The following urban features can create urban flooding or make inland floods worse:. Paved roads and streets.
Low-capacity drainage equipment. Dense buildings. Low amounts of green space. The most well-known and deadly type of flood is a flash flood. What is a Flash Flood? A flash flood is flooding that begins within 6 hours, and often within 3 hours, of heavy rainfall or other cause. What Causes Flash Floods? Most flash floods happen after extremely intense rainfall from severe thunderstorms over a short period of time normally 6 hours or less.
There are two key elements to determine is flash flooding is likely:. Rainfall rate. Rainfall duration. Flash floods also happen when damns break, when levees fail, or when an ice jam releases a large amount of water. Dangers of Flash Floods. Flash flooding is the 1 severe weather killer in the United States.
Flash floods are extremely powerful. They have enough force to roll boulders, tear trees from the ground, destroy buildings and bridges, and scour out new channels. Learn here about flood preparation and safety tips. Flooding, particularly in river floodplains, is as natural as rain and has been occurring for millions of years.
Famously fertile floodplains such as the Mississippi Valley, the Nile River Valley in Egypt, and the Tigris-Euphrates in the Middle East have supported agriculture for millennia because annual flooding has left tons of nutrient-rich silt deposits behind. Humans have increased the risk of death and damage by increasingly building homes, businesses, and infrastructure in vulnerable floodplains.
To try to mitigate the risk, many governments mandate that residents of flood-prone areas purchase flood insurance and set construction requirements aimed at making buildings more flood resistant—with varying degrees of success. Massive efforts to mitigate and redirect inevitable floods have resulted in some of the most ambitious engineering efforts ever seen, including New Orleans's extensive levee system and massive dikes and dams in the Netherlands.
Such efforts continue today as climate change continues to put pressure on vulnerable areas. Some flood-prone cities in the U. All rights reserved. Floods No other kind of natural disaster in America has caused more death and destruction than floods.
Learn about different kinds of floods and what causes them. How floods form A flood occurs when water inundates land that's normally dry, which can happen in a multitude of ways. Share Tweet Email. Why it's so hard to treat pain in infants. This wild African cat has adapted to life in a big city.
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