The SLOSH Model

We talk a lot about the computer models we use in helping us forecast the weather. Because of Oklahoma’s extreme weather, we tend to scour over available model data everyday.  It’s a vital component to our forecasting. Just as there are computer models which help forecast fronts and temperatures and severe weather, there are models that help forecast for hurricanes.

The specific one I’m focusing on today is called the SLOSH model. It stands for Sea, Lake and Overland Surges from Hurricanes. It doesn’t forecast the track or strength of hurricane, rather it’s used to” estimate storm surge heights resulting from historical, hypothetical, or predicted hurricanes by taking into account the atmospheric pressure, size, forward speed, and track data.”

What I found interesting is that the SLOSH model consists of a set of physics equations which are applied to a specific locale’s shoreline, incorporating the unique bay and river configurations, water depths, bridges, roads, levees and other physical features. In essence, it is a mesoscale model, very detailed for a small area. There are 37 such regions that the SLOSH model is divided into.

Here’s what the New Orleans basin looks like. Notice how fine a “mesh” the grid is divided into.

Predicting storm surge is a difficult, but very important part of hurricane forecasting. The storm surge, and the associated inland flooding, is the number one killer in a hurricane. Knowing how high the storm surge will be and how far inland the surge will affect, greatly helps Emergency Managers in issuing mandatory evacuations.

Here’s an animated SLOSH model from Hurricane Dennis 2005:

It is just a model, and shouldn’t be taken as the spoken word. The SLOSH model isn’t available to the public, and I doubt you would see it shown on television. You will see “storm surge” graphics on television, but they are normally much more generalized compared to this model. Predicting storm surge is tricky and if the model is incorrect, could be life-threatening if people didn’t evacuate solely based on this model.









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