VCC: Tornado-Alert Polygons in Visual Command Center (VCC) Do Not Match the National Weather Service (NWS) Polygon


The National Weather Service (NWS) polygon does not match the polygon shown on the map in Visual Command Center (VCC).

Root Cause:

The NWS updates the initial warning area which increases or decreases the polygon in VCC.

Example of an NWS Tornado Warning:

NWS Tornado Warning

Example of the VCC map before the NWS reduces the warning area:

VCC Map Polygon

Example of the VCC map after the NWS reduces the warning area:

VCC Map Polygon After Reduction

An NWS Tornado Warning is likely to have oddly shaped polygons that do not align with county boundaries due to the inability to pinpoint where a tornado will likely form.

Find out more about Storm-Based Warnings from the NWS.


This behavior is expected as tornado movement is unpredictable.

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