The National Weather Service (NWS) uses a standardized alert system to communicate the risk and severity of weather-related hazards. These alerts provide advance notice, allowing people time to prepare and take appropriate action based on the potential danger. The system ranges from general outlooks to urgent warnings. Understanding the specific terminology, such as a flood advisory, is important for gauging the actual risk to life and property.
Defining the Areal Flood Advisory
An Areal Flood Advisory is issued when flooding is expected to cause a significant inconvenience but is generally not severe enough to pose an immediate threat to life or property. The term “areal” simply indicates that the expected flooding will cover a broad geographic area, rather than being confined to a specific river or flash flood zone. This advisory is typically triggered by heavy rainfall over a short duration that overwhelms drainage systems or causes minor small stream overflow.
The flooding associated with this alert is often characterized as nuisance flooding. This includes the ponding of water on streets, minor flooding in low-lying areas, and water accumulation where drainage is poor, especially in urban environments. The advisory signals that these conditions are either occurring or are highly likely to develop, causing considerable disruption to travel and daily activities.
Understanding the Hierarchy: Advisory, Watch, and Warning
The National Weather Service employs a distinct hierarchy of alerts to communicate the potential and reality of flooding, placing the Advisory at the lowest end of the scale. This tiered approach helps the public quickly determine the severity of the expected event and the urgency of their response. Each level is based on the likelihood, timing, and impact of the flooding.
A Flood Advisory is the mildest alert, meaning a flood event is occurring or imminent, but the impacts are expected to be minor. It advises the public to be aware of potential hazards and exercise caution, but not to take immediate life-saving action. The intent is to inform people about conditions that will likely cause inconvenience, such as road closures due to standing water.
A Flood Watch is a more serious alert, meaning that conditions are favorable for flooding to occur, but it is not yet happening or imminent. This alert is issued to encourage preparedness because the potential threat exists, often over the next 12 to 48 hours. A watch indicates the possibility of a flood event, signaling that a higher-level alert may be issued later.
A Flood Warning is the most severe alert, indicating that flooding is occurring or is highly likely to occur and poses an immediate threat to life and property. This warning demands immediate action, as the situation is considered severe and potentially life-threatening. The water is expected to rise to levels that will cause major damage, warranting immediate protective measures or evacuation if advised by local officials.
Necessary Public Response to an Advisory
The primary action required during an Areal Flood Advisory is increased awareness and caution. Residents should monitor local weather conditions and official NWS updates, as a developing situation could escalate to a watch or warning. Even though the flood itself may be minor, driving or walking through any standing water introduces an unnecessary risk.
Even in minor flooding, the public must strictly avoid driving into areas where water covers the road surface. The phrase “Turn Around, Don’t Drown” is the standard safety message for all flood events because it is impossible to gauge the depth or the integrity of the road beneath the water. Only six inches of moving water can knock an adult off their feet, and just one foot of water can float many vehicles.
People living in low-lying areas or flood-prone basements should take simple preparatory steps, such as moving items off the floor and securing any outdoor furniture. Travelers should allow for extra time, as flooded streets and poor visibility will slow traffic and may force re-routing. The response to an advisory is one of vigilance and caution.