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Currently showing: Climate/natural disasters > Floods/storms

13 Sep 18 14:34

Hurricane Florence – getting the big picture right with geo maps

When a severe storm like Hurricane Florence is heading for a densely populated coastal area, it's prudent for residents to prepare for the worst and hope for the best. It's not so much different for the insurance industry, which must be able to anticipate potential losses, but do so as realistically as possible and in a timely manner – in other words, knowing early on what could happen where and how an insured portfolio could be affected.

Here's a simple and effective way to do just that:

Since it's usually highly uncertain where exactly a storm makes landfall, a quick check can be good enough to start with. The key is to combine the right data and integrate it in a map. You might find what you need on one of numerous web pages, but for more customized results you will typically want to combine the relevant elements on your own in a mapping tool. Let me explain how this works with a few maps from CatNet®.

Step one

To get the big picture about the potential impact, it is useful to combine a forecast footprint, for example a kml file from NOAA, with a map presenting the population density. You will quickly see that the big centers are further inland and less at risk, but some hot spots can also be found along the coast.
Figure.1: Forecast as of 13th September 2019. Source: NOAA, Esri, FAO, Google, INEGI, Swiss Re CatNet.

Step two

A next step is to zoom further into the landfall region to identify a worst case storm surge scenario using Swiss Re's modeled storm surge hazard zones to assess even extreme events. Florence is a SS2 storm and will rather not trigger a 50y surge.
Figure.2: Storm surge hazard zones for extreme events up to 1000y return period. Source: Swiss Re CatNet.

Step three

If you have your geo-referenced locations at hand you may want to dig deeper and do a quick overlay. You hopefully realized that at least from the surge impact you have not to expect the worst.
Figure.3: Surge zones including imported locations. Source: Google maps, Swiss Re CatNet.

Step four

A last check of the wind hazard map shows that further inland the expected wind gust of a major storm reaches only a moderate level.
Figure.4: Maximum wind speed expected on average once every 50y. Source: Swiss Re CatNet.

Using a map based approach may take you less than half an hour and gives you the confidence to either wait until after the landfall before you start an in-depth loss assessment or to dig deeper right-away.

Category: Climate/natural disasters: Floods/storms

Location: USA


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