When the Coast Pushes Back: Translating Coastal Conditions into Actionable Flood Intelligence

Discover how FloodWise^TM integrates storm surge, coastal forecasts, rainfall, and H&H modeling to deliver localized, actionable flood intelligence before impacts occur.

For coastal communities, some of the most consequential flooding during a hurricane may not come from the rain falling overhead, but rather from the ocean moving inland.

Storm surge can transform a coastal storm from a weather event into a widespread flooding emergency, inundating roads, isolating communities, restricting access to critical facilities, and interacting with rainfall and drainage systems in ways that can dramatically escalate local flood conditions.

A critical part of that picture is understanding what happens when coastal waters move inland.

FloodWise^TM incorporates storm surge and coastal water levels directly into its real-time forecasting process, allowing communities to evaluate how changes in coastal conditions interact with rainfall, drainage networks, and local hydrologic and hydraulic (H&H) systems to influence the location, depth, and extent of flooding.

For coastal communities, emergency managers, transportation agencies, stormwater professionals, and other key decision makers, that distinction is significant.

So, What Exactly Is Storm Surge?

Storm surge is the abnormal rise in seawater level generated by a storm, measured above the water level that would normally be expected from the astronomical tide.

Its primary driver is wind. As powerful storm winds push enormous volumes of ocean water toward the coast, water begins to accumulate along the shoreline. Atmospheric pressure can contribute to the rise, while coastal geography, bathymetry, the storm's size and intensity, forward speed, and angle of approach can all influence how severe the surge becomes at any one location.

That makes storm surge highly dependent on where a storm is going, how it approaches, and the characteristics of the coastline it encounters.

But knowing the forecasted coastal water level is only part of the problem.

For a community preparing for impact, the more pressing question is:

What will that water do once it arrives?

Turning Storm Surge into Local Flood Intelligence

This is where FloodWise^TM adds a vital layer of intelligence.

FloodWise^TM integrates coastal ocean forecast information from the National Oceanic and Atmospheric Administration (NOAA), including forecast guidance from the Surge and Tide Operational Forecast System, or STOFS.

STOFS-2D-Global runs four times daily and provides numerical storm surge and tide forecast guidance out to approximately 180 hours, or 7.5 days. FloodWise^TM can retrieve this coastal forecast information and incorporate it into the local forecasting process.

For storm-surge applications, forecasted coastal stages can be introduced into the model via coastal nesting points. These locations pull time-stage information from the STOFS forecast and use it as a coastal boundary condition within the H&H model.

In simpler terms:

FloodWise^TM doesn’t just tell users that the ocean is expected to rise; it models how that rising water may affect a given community along the coast.

From the Coastline to the Street

Once the coastal forecast information is incorporated, FloodWise^TM routes those conditions through

StormWise^TM, Streamline Technologies’ physics-based hydrologic and hydraulic (H&H) modeling engine.
StormWise^TM calculates flows and water-surface elevations throughout the modeled network. Forecast results are then returned to FloodWise^TM, where they can be visualized through its intuitive web-based dashboard.

That creates the connection that is critical during a coastal storm: regional coastal forecast → local hydraulic response → localized flood impacts.

Instead of stopping at a predicted surge elevation offshore or along the coastline, FloodWise^TM can help identify what those conditions could mean for roads, structures, infrastructure, and other locations within the modeled community.

Flood Risk Points^TM further translates forecast results into localized information at the street, house, and critical infrastructure levels, helping users understand potential impacts where operational decisions are actually made.

Where Storm Surge Meets Rainfall

Storm surge rarely occurs in isolation. During a hurricane or coastal storm event, elevated water levels can coincide with significant rainfall across the watershed, creating conditions in which coastal and inland flooding influence one another.

As rainfall moves through the drainage system, elevated coastal water levels can reduce the system’s ability to discharge efficiently, slowing drainage and increasing the potential for water to accumulate further inland. This interaction is commonly referred to as compound flooding.

FloodWise^TM accounts for this dynamic by incorporating NOAA coastal ocean forecasts alongside inland rainfall and routing both through StormWise^TM. By evaluating these conditions within the same H&H framework, the system can represent how coastal boundary conditions may influence flooding throughout the broader watershed.

This provides a more complete picture of flood behavior during coastal events, particularly in communities where storm surge, rainfall, and drainage infrastructure are closely interconnected.

Hurricane Idalia: Seeing the Impact Before It Arrived

For Hurricane Idalia (2023), a FloodWise^TM hindcast was used to assess the forecast accuracy of coastal flooding affecting Cedar Key, FL.

Coastal nesting points incorporated forecasted stage information from STOFS into the modeled system, allowing the forecast to represent water moving into the island.

The resulting Flood Risk Points^TM showed extensive impacts, including significant flooding along State Road 24, the critical roadway connecting Cedar Key with the mainland.

FloodWise^TM forecasted the flooding approximately 48 hours in advance.

Think about what 48 hours can mean when storm surge threatens a community.

It can mean more time to evaluate evacuation decisions.
More time to identify when an access road may need to be closed.
More time to move equipment.
More time to consider temporary flood protection.
More time to communicate potential impacts.

And because the forecast can also help users understand when floodwaters may recede, it can provide vital information for planning and recovery operations.

The value of the forecast is not simply knowing that water is coming; it’s understanding where, when, and how that water may disrupt the community before it arrives.

Coastal Conditions to Local Decisions

FloodWise^TM operates continuously, 24/7/365, bringing forecast data, coastal conditions, and local H&H modeling together within a single platform. As conditions evolve, users can also explore “what-if” scenarios directly from the dashboard to better understand how changes in assumptions may affect potential flood impacts.

For coastal communities, that broader perspective is especially important. Flooding is rarely driven by a single factor, and FloodWise^TM reflects this reality by accounting for rainfall, inland hydrology and hydraulics, and coastal influences such as storm surge in the forecasting process.

As flood events become increasingly complex, the ability to connect forecasted coastal conditions with localized impacts will only become more valuable.

Knowing that storm surge is possible is important. Understanding where that water may go, when impacts may occur, how deep flooding could become, and what roads, infrastructure, and critical assets may be affected provides something even more valuable: actionable foresight.

That is where FloodWise^TM transforms a coastal forecast into information communities can use to prepare earlier, respond more strategically, and make better-informed decisions before the water arrives.

Contact our team to learn how FloodWise^TM can help your community better understand storm surge, anticipate localized flood impacts, and turn coastal forecasts into actionable insight before the water arrives.