Thunderstorms are identified by cold cloud tops from the GOES-11/12 IR window channel (11 micron) imagery or from radar echos. An algorithm originally developed by Brian Mapes (19??) is used to automatically detect cloud clusters with temperatures less than a cloud top temperature threshold. Here, the algorithm has been adapted to identify and track areas where the radar reflectivity exceeds a threshold. The areas or clusters can be followed in time by searching for partial overlap in their position between successive images. (This implies that for a given speed of movement and image frequency, that the clusters must exceed a certain size threshold to be sucessfully tracked. For example, the diameter must be greater than 15 km for a movement of up to 60 km/hr and 15 min image frequency). A time series of the centroid position, surface area, mean, maximum and mimimum reflectivity are evaluated for each cluster.
    When run on GOES data, the cloud tracks can be displayed for different cloud top temperature thresholds ranging from -43 to -73 deg. C.  For WSR-88 data, the algorithm is run with different reflectivity thresholds (5 dbZ intervals from 30 to 60 dbZ).  For each value, a unique set of precipitation clusters, tracks and reflectivity statistics are obtained. The user can decide which threshold to use in displaying the output.
    Real-time movies include data from the past 3 hours and and future projection of images from the K-means algorithm developed by V. Lakshmanan of NSSL and CIMMS University of Oklahoma.

Fig. 1.  GOES movies
Past 3 hours
 Including 60,120 minute nowcast

Fig. 2.  WSR-88D movies
Past 3 hours
Including 30, 60 minute nowcast

    Java based applications used for interactive animations were developed by Tom Whittaker of the Space Science and Engineering Center, University of Wisconsin-Madison. The animations can take a while to load, depending on network speed, computer systems, etc. Also, there can be a problem viewing these on certain machines (Macs).