A Flood Advisory, issued by the National Weather Service (NWS), serves as the lowest level of flood alert, signaling that minor flooding is either expected or already occurring. This alert primarily indicates a nuisance-level event, meaning the flooding is not anticipated to be a significant threat to life or property. It should be viewed as a “Be Aware” notification, prompting simple, precautionary actions rather than immediate emergency responses.
The Specific Conditions That Trigger a Flood Advisory
An advisory is typically issued when conditions lead to elevated stream flow or the collection of significant standing water that creates an inconvenience for the public. This type of alert is often designated as an Urban and Small Stream Flood Advisory, focusing on areas with poor drainage systems. The conditions might include water ponding on streets, flooding in low-lying areas, or minor overflows of small creeks and streams that remain within their banks or only slightly exceed them.
The flooding associated with an advisory is generally shallow and localized, resulting from heavy rain that overwhelms the capacity of storm drains and ditches. While this can cause travel delays and make some roads temporarily impassable, it does not typically require widespread evacuation or major road closures. This minor flooding is usually characterized by minimal or no property damage, though it can still be hazardous if caution is not exercised. For instance, a Coastal Flood Advisory is issued when minor tidal overflow is expected, with water levels potentially reaching up to one foot above ground level in low-lying coastal areas.
Understanding the Difference Between Advisories, Watches, and Warnings
The National Weather Service utilizes a tiered system of alerts to communicate the severity and imminence of flooding. A Flood Advisory represents the lowest tier, indicating that a specific weather event may become a nuisance but is not expected to be severe enough to warrant a full warning. This “Be Aware” status means minor flooding is occurring or anticipated.
Moving up the scale, a Flood Watch is a higher-level alert, signifying that conditions are favorable for flooding to occur, but it is neither imminent nor certain. This “Be Prepared” stage is issued when the ingredients for a flood are present, such as heavy rain, and it is meant to inform the public that they should monitor the situation and be ready to take action if the forecast worsens. A Watch signals a potential for rapid or widespread flooding to develop within the next 12 to 48 hours.
The most severe alerts are the Flood Warning and the Flash Flood Warning, which represent the “Take Action” stage. A Flood Warning is issued when flooding is imminent or already occurring, posing a significant threat to life and property, often due to rivers rising out of their banks or prolonged, heavy rainfall. A Flash Flood Warning is the most urgent, issued when a sudden, violent flood is imminent or in progress, typically developing rapidly within six hours or less and requiring immediate movement to higher ground.
Essential Safety Measures During an Advisory
When a Flood Advisory is in effect, the primary actions focus on caution and avoiding preventable hazards associated with standing water. The most important safety principle is to never drive through flooded roadways, a concept summarized by the phrase, “Turn Around, Don’t Drown.” As little as six inches of moving water can cause a person to fall, and one to two feet of rushing water is enough to sweep away most vehicles.
Motorists should use extra caution when traveling, as standing water can hide washed-out road surfaces and increase the risk of hydroplaning. It is advisable to allow for extra travel time and to avoid areas known for poor drainage or low-lying roads. Securing loose outdoor items, such as trash cans and patio furniture, is a sensible precaution to prevent them from floating away or becoming debris. Residents should monitor local weather updates and official NWS information, recognizing that an Advisory could quickly escalate to a Watch or Warning if rainfall intensity increases.