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Tracking storm cells with Xweather Flex

4.12.2017//Developer, Tutorials, API & Mapping

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Where are the storms? Where are they heading? What cities are in their path? These are just some of the common questions that can be answered with data from current storm cells.

Lee Huffman

Chief Technology Officer, AerisWeather

The stormcells endpoint provides information on individual storm cells across the United States, including Puerto Rico and Guam. Storm cell information is a radar-derived product that attempts to identify and track storm movement. Cell intensity and severe weather signatures within the cell, such as rotation and hail, are also reported. When available, the forecast track can be obtained as a polygon cone or as a line.

The following information is provided by the endpoint:

  • Storm location

  • Storm direction, speed, and forecast

  • Hail potential and size

  • Storm showing a tornadic signature

  • Cell with significant rotation

  • Precipitation rate

  • Cloud heights

While the Xweather API provides a lot of useful data about storms and severe weather, plotting them on a map tells a better story for particular events. The Xweather raster mapping offering provides many options for creating storm cell visuals.

Storm cell layer

With Xweather's raster maps, you can use the storm cells layer to easily overlay storm cells onto static maps or use as tiles with any third-party mapping library.

For example, here's a static map with radar and storm cells centered on Atlanta, GA at zoom level 8:

In this example, we're plotting all available cells — even general storms that indicate no significant threats other than light to moderate rainfall.

Xweather's raster maps allow you to filter the storm cells to show only those cells with potential threats, such as hail, significant rotation, and tornadic signatures. Simply adjust the layer name from stormcells to stormcells-major:

Likewise, you can replace -major with -hail, -rotating, or -tornado to filter the cells displayed even further. For example, below we use the above example filtered for hail-related cells only:

Storm cells using interactive maps

You'll find examples of further customization for storm reports visuals in our documentation, including an example detailing how to add storm cells as point data instead of a static image overlay. The following code provides an example map with cells displayed as individual markers.

Rendering storm cells as point data using a mapping library allows you to add interaction to your cells, such as clicking or tapping on a cell's marker on the map to display more details about that cell. You can also request a list of major cities currently in the forecast path of a particular cell.

Storm cells using a Leaflet map

Leaflet.js is a commonly used open-source mapping library. Integrating storm cells with a Leaflet map is simplified since the Xweather API supports outputting data in GeoJSON. GeoJSON is a common method for transferring geospatial data between systems and is supported by many modern mapping platforms, including Leaflet.

When adding storm cells to a Leaflet map, an API query similar to the following could be used:

The above URL would fetch up to 1000 storm cells across the US. With this URL you could follow the process used with our storm reports article to add the storm cells to your Leaflet map.

If mapping storm cells isn't your goal, querying the data directly using our AerisWeather API also has many useful purposes for custom applications.

Nearby storm cells

The API will return the 10 closest cells within a 25-mile radius if you pass a location to the storm cells endpoint:

The API will return "no data available" if no storm cells are found within 25 miles of the location. The location can be a city, state, US zip code, coordinate or any of the other supported place formats.

To extend the radius of the search to 50 miles, we can add radius=50miles to the query:

Distance from storm cells

The relativeTo JSON object for each storm cell result provides the bearing from the requested location and the distance:

This information, combined with the cell's direction and speed, is very useful for determining if the cell is approaching the location and how long it may take for the storm to arrive.

Filtering storm cells

When requesting storm cell data, the API will return information on any cell by default. This includes general storms that may not indicate significant weather threats. The stormcells endpoint provides a variety of filters to limit results.

For example, to limit the result to just storm cells with hail:

Or, limit to cells with intense rainfall:

Filters can also be combined, such as returning results that include both hail and intense rainfall.

Along with filters, the storm cells endpoint offers a variety of query options that can be used to limit results further. For example, find the 10 closest storm cells with a high probability of hail with a diameter 1" or greater:

We can also sort the results by potential hail size, largest to smallest, using sort parameters:

Searching storm cells

One unique feature of the Xweather API is the search action, which allows you to perform advanced queries that may not pertain to a specific location. When used with the storm cells endpoint, you have the ability to search across the entire US, a single state, or multiple.

For example, return up to 100 storm cells that indicate a tornadic vortex signature (TVS) (if there are more than 100 cells with a tornadic signature at a given time, we may have bigger problems):

Or, return up to 100 storm cells within the state of Minnesota that have a diameter estimated to be 1.5" or greater in size, sorted by hail size:

Locations within a storm cell's path

Most of the time storms will provide forecast path data, at which point the API will also provide a forecast cone to indicate the potentially affected locations. Using the affects action with the storm cells endpoint, you can obtain a list of the cities within an individual cell's forecast.

A unique id is provided with each storm cell response, which will look similar to DXY_B4. When you query the affects action, use the id of the cell you wish to query and the API will return a list of cities within the storm's forecast cone. Only cities with a population of 25,000 or more are returned by default:

The above request would return the top 10 locations, by population, within the forecast path of storm cell with id of DYX_B4.

If you would like to return locations with a minimum population of 1,000, then you can add query=pop:1000 :

Start tracking storm cells

We’ve reviewed the many capabilities of the storm cells endpoint--from static maps and interactive maps, to querying the raw data directly. Severe weather season is well underway, so get started with our free developer account to experiment with integrating storm cell information to your own applications and alerting platforms today!

 

Lee Huffman

Chief Technology Officer, AerisWeather

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