How to interpret post-event hurricane footprints

by Jen Smoldt on September 17, 2018

KatRisk flood

KatRisk’s inland flood depth footprint is just one of the many Hurricane Florence post-event footprints now accessible in SpatialKey.

Hurricane Florence is now a tropical depression with extensive river flooding being the primary concern. As you work to understand the extent of damage, respond to claims, and even identify potentially fraudulent claims, post-event data is a critical component in your mitigation and response efforts. With Florence reminiscent of Hurricane Harvey flooding, it’s time to refresh your understanding of how to interpret post-event footprints.

Whether you use SpatialKey for your analysis, or another data enrichment and geospatial analytics solution, here are a few tips and definitions to help you make sense of event footprints, as well as a listing of the post-event data that is, or will be, accessible within SpatialKey, including Aon Impact Forecasting, KatRisk, JBA, NOAA, and FEMA:

Florence data table 9-18 v2


How to interpret post-event footprints

A post event footprint is the measurement of the severity or impact of an event, which when mapped, produces a footprint of the event. This allows insurers to understand their loss potential for events such as hurricanes and wildfires.

Here are a few definitions for your reference:

    • Wind band extent - footprint of wind speeds and wind category bands
    • Inland flood extent - footprint of flooding during a hurricane caused by extreme precipitation over a prolonged period of time, these typically include flood depths
    • Storm surge extent - footprint of flooding caused by a hurricane with high tidal waves, these typically include flood depths
    • Coastal flood - same as storm surge
    • Forecasted wind, flood, precipitation, and surge - prediction or estimation of a future event

For example, in the case of a hurricane, you may see extents for wind, flood, or surge (coastal flood), and each of these components will have their own varying extent footprints. These would not contain any data other than the area that was impacted by the event.

Aon Flood extent Harvey

This shows a view from within SpatialKey of a flood extent footprint without additional depth detail from Hurricane Harvey.

An extent with severity, such as flood depth or wind speed, contains a column of data pertaining to the severity of a given area within that extent. For example, a wind extent could show wind speed bands and highlight the most severe impacted areas.

JBA flood depth bands Harvey

This is an extent using JBA data with a column of data representing severity of flood depth bands. These bands show where the flood depths were the highest and lowest over the extent of the event.     

Here is another example of an extent with a column representing severity:  

KatRisk wind speeds Matthew

This extent using KatRisk data shows wind speed and the category of the hurricane.

Post-event data accessible in SpatialKey

At SpatialKey, we partner with a variety of leading third-party data providers to help inform your potential losses, as well as help you understand multiple views of risk. Contact us to access data from the following sources, or reach out to your SpatialKey account manager directly:

  • Aon Impact Forecasting: We’ll release the following versions as separate models to show how they’ve been adjusted over time as information on the ground becomes available:  
    • Inland flood extent
    • Storm surge extent
    • Wind band extent
  • JBA Risk Management: JBA’s flood hazard maps for pluvial flood are based on extensive research into the areas inundated. They produce two sets of data: 1) flood event footprint 2) flood event footprint with inundation depths:
    • Inland flood extent
    • Inland flood depth extent
    • Coastal flood extent (storm surge)
    • Coastal flood depth extent
  • KatRisk: The following models will be updated with new versions as available. We will release these versions as separate models so that clients may see how the model has been adjusted over time:
    • Inland flood depth extent
    • Storm surge depth extent
    • Wind speed band extent


  • NOAA
    • Post-event aerial imagery - updated daily 
    • Forecasted flood - General outlook for significant river flooding
    • Forecasted precipitation - Expected amount of precipitation accumulated over a specified time
    • Forecasted surge - Storm surge model in use by the National Weather Service (NWS) to help forecast surge from hurricanes
    • Forecasted wind -  Winds speeds and wind category bands
  • FEMA
    • Inland flood extent
    • Coastal flood extent
Check back often for data availability information. For tutorials to help you conduct portfolio analysis, visualize storm surge, join datasets, import data, and access SpatialKey’s Data Mart, visit our Support site

Topics: Hurricane Data, Flood, Hurricane Florence

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