Severe Weather 101
Since flood damage is almost never covered by homeowners insurance, flood insurance is important for people living in high-risk flood zones. To stay safe during a flood, go to the highest ground of floor possible. If your skin comes in contact with flood water, make sure to wash it with soap and disinfected water because the contents are unknown. A flood inundates a floodplain. Most floods fall into three major categories: riverine flooding, coastal flooding, and shallow flooding. Alluvial fan flooding is another type of flooding more common in the mountainous western states. National Flood Insurance Program Requirements. 59.1 - Definition. Flood Coverage Homes are at risk from flooding by everything from heavy rains to tidal water. We’ll help you get coverage for floods through the National Flood Insurance Program.
Flood Basics
Weather Briefly: Flooding. Watch on the NOAA Weather Partners YouTube Channel»
- What is flooding?
- Flooding is an overflowing of water onto land that is normally dry. Floods can happen during heavy rains, when ocean waves come on shore, when snow melts quickly, or when dams or levees break. Damaging flooding may happen with only a few inches of water, or it may cover a house to the rooftop. Floods can occur within minutes or over a long period, and may last days, weeks, or longer. Floods are the most common and widespread of all weather-related natural disasters.
Flash floods are the most dangerous kind of floods, because they combine the destructive power of a flood with incredible speed. Flash floods occur when heavy rainfall exceeds the ability of the ground to absorb it. They also occur when water fills normally dry creeks or streams or enough water accumulates for streams to overtop their banks, causing rapid rises of water in a short amount of time. They can happen within minutes of the causative rainfall, limiting the time available to warn and protect the public. - Where and when do floods occur?
- Flooding occurs in every U.S. state and territory, and is a threat experienced anywhere in the world that receives rain. In the U.S. floods kill more people each year than tornadoes, hurricanes or lightning.
- What areas are at risk from flash floods?
- Densely populated areas are at a high risk for flash floods. The construction of buildings, highways, driveways, and parking lots increases runoff by reducing the amount of rain absorbed by the ground. This runoff increases the flash flood potential.
Sometimes, streams through cities and towns are routed underground into storm drains. During heavy rain, the storm drains can become overwhelmed or plugged by debris and flood the roads and buildings nearby. Low spots, such as underpasses, underground parking garages, basements, and low water crossings can become death traps.
Areas near rivers are at risk from floods. Embankments, known as levees, are often built along rivers and are used to prevent high water from flooding bordering land. In 1993, many levees failed along the Mississippi River, resulting in devastating floods. The city of New Orleans experienced massive devastating flooding days after Hurricane Katrina came onshore in 2005 due to the failure of levees designed to protect the city.
Dam failures can send a sudden destructive surge of water downstream. In 1889 a dam break upstream from Johnstown, Pennsylvania, released a 30-40 foot wall of water that killed 2200 people within minutes.
Mountains and steep hills produce rapid runoff, which causes streams to rise quickly. Rocks and shallow, clayey soils do not allow much water to infiltrate into the ground. Saturated soils can also lead to rapid flash flooding. Camping or recreating along streams or rivers can be a risk if there are thunderstorms in the area. A creek only 6 inches deep in mountainous areas can swell to a 10-foot deep raging river in less than an hour if a thunderstorm lingers over an area for an extended period of time. Sometimes the thunderstorms that produce the heavy rainfall may happen well upstream from the impacted area, making it harder to recognize a dangerous situation.
Very intense rainfall can produce flooding even on dry soil. In the West, most canyons, small streams and dry arroyos are not easily recognizable as a source of danger. The causative rainfall can occur upstream of the canyon, and hikers can be trapped by rapidly rising water. Floodwaters can carry fast-moving debris that pose significant risks to life.
Additional high-risk locations include recent burn areas in mountains, and urban areas from pavement and roofs which enhance runoff.
Ice jams and snowmelt can help cause flash floods. A deep snowpack increases runoff produced by melting snow. Heavy spring rains falling on melting snowpack can produce flash flooding. Melting snowpack may also contribute to floods produced by ice jams on creeks and rivers. Thick layers of ice often form on streams and rivers during the winter. Melting snow and/or warm rain running into the streams may lift and break this ice, allowing large chunks of ice to jam against bridges or other structures. This causes the water to rapidly rise behind the ice jam. If the water is suddenly released, serious flash flooding could occur downstream. Huge chunks of ice can be pushed onto the shore and through houses and buildings.
National Weather Service Messaging Terminology
- FLASH FLOOD WATCH or FLOOD WATCH
- Flash flooding or flooding is possible within the designated watch area — be alert.
- FLASH FLOOD WARNING or FLOOD WARNING
- Flash flooding or flooding has been reported or is imminent — take necessary precautions at once! Get to higher ground!
Turn around, don’t drown! Most fatalities in the US from flash flooding are from vehicles driving into flooded roadways. - URBAN and SMALL STREAM ADVISORY
- Flooding of small streams, streets and low-lying areas, such as railroad underpasses and urban storm drains is occurring.
- FLASH FLOOD STATEMENT or FLOOD STATEMENT
- Follow-up information regarding a flash flood/flood event.
What we do: In order to evaluate the forecasting tools, we need observations of flash flooding. NSSL has assembled flash flood observations from USGS automated discharge measurements, trained spotter reports from the NWS, and from NSSL's Severe Hazards Analysis and Verification Experiment (SHAVE). This database is available for community research purposes.
NSSL has developed the state-of-the-science system for estimating heavy rainfall and resultant flash flooding. The Multi-Radar Multi-Sensor system provides rainfall rate estimates across the U.S. every two minutes, and these are input to a suite of hydrologic models and forecasting tools within the Flooded Locations and Simulated Hydrographs (FLASH) system.
Richard Flood
We’re proud of our flood-related expertise and our ability to provide flood data that is both current and compliant with federal regulations. Our knowledgeable team of servicing specialists and compliance experts use resources that are advocated by FEMA, the NFIP and Federal Regulators.
Our Compliance Advisors and Dispute Resolution Specialists are available 7 a.m. to 7 p.m. Central time, Monday through Friday, at (800) 447-1772. Our specialists have earned national certification as floodplain managers with some also earning an Associate in Flood Insurance accreditation, to assist you with:
- Questions over Flood Determinations and flood map issues
- Regulatory or compliance questions
- Help with borrower requests such as through the flood map amendment process
- Working with FEMA and community officials to identify flood mapping issues
Flood Risk By Address
We understand that from time to time you may encounter conflicting flood zone information. As a service to you, we will recheck our work. You can start the 'dispute' process either from FloodCert.com (you'll need to have an account with us) or by calling our Client Services Department. Once the dispute is initiated, our team will pull together the relevant resources, and our Dispute Resolution Specialists will recheck each aspect of the determination for accuracy and contact you with the results. If you or your borrower has questions about the LOMA application process, we'd be happy to help. For FEMA guidance on LOMA applications, click here.
Flood Zone Maps
We also created the CoreLogic Flood Compliance Kit to assist you with the process of what to do when you or your borrower disagree with a determination. This kit provides detailed information about the steps to take to dispute a determination, how to apply for a Letter of Map Amendment or Lender Determination Review through FEMA, and other helpful reference and contact information.