A method for achieving extreme levels of compression of high-volume weather radar data is presented. Weather reflectivity contours, as per National Weather Service or custom thresholds, are processed by tracing their departure from a smoothed version to obtain the local extrema which serve as control points. The control points, which are transmitted in relative coordinates for further compression, are interpolated using a second-degree B-spline to retrieve the contours. The encoding-decoding method is capable of capturing the random undulations inherent in weather contours. It is shown that over two orders of magnitude of compression is possible without perceptible loss of meteorological information. Multiple enhancements to the basic method are quantitatively studied and compared with the existing methods for radar data compression.