Flood watch
Encyclopedia
Flood alerts are issued by weather agencies to alert residents that flood conditions are a possibility for their area.
is issued when weather conditions are favorable for very heavy rain
and flash flood
ing. A watch does not mean that flooding is actually occurring, only that conditions have created or will create a significant risk for it. If flooding actually does occur, a flood warning and urgent action should be taken.
A flood warning
or flash flood warning
is issued when flood
ing in a certain area is imminent or occurring.
, a heavy rainfall warning (which indicates rainfall amounts that could produce flooding are expected) has basically the same meaning as a flood watch.
In the United States
, the National Weather Service
issues watches and warnings for flooding on a per-county basis. When a flood warning is issued in the United States it means a river
or creek is in flood.
In Australia
, the Bureau of Meteorology
issues a flood watch that covers similar conditions to the United States Flood Watch, however, it is known by slightly different names in some states.
In Europe, there is the European Flood Alert System
.
Types of flood alerts
A flash flood watchFlash flood watch
A Flash flood watch is issued by the National Weather Service when conditions are favorable for flash flooding in flood-prone areas where grounds are already saturated from recent rains....
is issued when weather conditions are favorable for very heavy rain
Rain
Rain is liquid precipitation, as opposed to non-liquid kinds of precipitation such as snow, hail and sleet. Rain requires the presence of a thick layer of the atmosphere to have temperatures above the melting point of water near and above the Earth's surface...
and flash flood
Flash flood
A flash flood is a rapid flooding of geomorphic low-lying areas—washes, rivers, dry lakes and basins. It may be caused by heavy rain associated with a storm, hurricane, or tropical storm or meltwater from ice or snow flowing over ice sheets or snowfields...
ing. A watch does not mean that flooding is actually occurring, only that conditions have created or will create a significant risk for it. If flooding actually does occur, a flood warning and urgent action should be taken.
A flood warning
Flood warning
Flood warning is closely linked to the task of flood forecasting. The distinction between the two is that the outcome of flood forecasting is a set of forecast time-profiles of channel flows or river levels at various locations, while "flood warning" is the task of making use of these forecasts to...
or flash flood warning
Flash Flood Warning
A Flash Flood Warning is issued when a flash flood is imminent or occurring in the warned area. A flash flood is a sudden, violent flood after a heavy rain...
is issued when flood
Flood
A flood is an overflow of an expanse of water that submerges land. The EU Floods directive defines a flood as a temporary covering by water of land not normally covered by water...
ing in a certain area is imminent or occurring.
Flood alerts by country
In CanadaCanada
Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...
, a heavy rainfall warning (which indicates rainfall amounts that could produce flooding are expected) has basically the same meaning as a flood watch.
In the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
, the National Weather Service
National Weather Service
The National Weather Service , once known as the Weather Bureau, is one of the six scientific agencies that make up the National Oceanic and Atmospheric Administration of the United States government...
issues watches and warnings for flooding on a per-county basis. When a flood warning is issued in the United States it means a river
River
A river is a natural watercourse, usually freshwater, flowing towards an ocean, a lake, a sea, or another river. In a few cases, a river simply flows into the ground or dries up completely before reaching another body of water. Small rivers may also be called by several other names, including...
or creek is in flood.
In Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
, the Bureau of Meteorology
Bureau of Meteorology
The Bureau of Meteorology is an Executive Agency of the Australian Government responsible for providing weather services to Australia and surrounding areas. It was established in 1906 under the Meteorology Act, and brought together the state meteorological services that existed before then...
issues a flood watch that covers similar conditions to the United States Flood Watch, however, it is known by slightly different names in some states.
In Europe, there is the European Flood Alert System
European Flood Alert System
The European Flood Alert System project is a European Commission initiative to increase preparedness for riverine floods across Europe.- History :Over the last decades severe fluvial floods of trans-national dimensions have taken place in Europe...
.