Their main weather tool is GRLevel3, software that massages government-supplied radar images to produce wonderfully detailed images.
The NOAA's raw radar feeds are actually quite blocky, like this:
GRLevel3 uses your graphics card or chip to interpolate and smooth the image to something like this:
Your local TV station and your favorite weather sites probably use the same kind of smoothing. Of course, all forms of interpolation and smoothing are mathematical guesses as to what things would look like if we had more complete data. In this case, the guesses are of the educated sort, and can be quite reasonably accurate. But it's good to remember that they are, in fact, guesses. All we really have is the blocky data.
GRLevel3 isn't terribly expensive (free for three weeks, then $80 to keep), and its large-screen format is gorgeous. But because it's using the same raw data and kind of smoothing that's available to anyone, I wondered about freeware alternatives that might be just as good, at least for armchair storm chasing.
Here what I came up with.
I've been a member of the Wunderground.com weather geek site for a long time. The site is free (ad supported), or you can get no ads and enhanced features for 5 bucks for a full year; an incredible bargain.
Use http://www.spc.noaa.gov/products/outlook/, Wunderground or your favorite Wx site to find severe weather areas. (When I say "Wunderground," substitute your personal favorite site, if you prefer.) Using any sources you wish pick out a specific storm or cell to "chase."
Get two browsers open side by side, so you can view both at the same time. With Wunderground open in one browser, open Acme Mapper in the other. Use Mapper's roadmap features to find the same storm area and scale as shown in your Wunderground radar image.
When the maps roughly match, use Mapper's Nexrad overlay. (It won't auto-update; when you see Wunderground's radar update, hit Refresh on the Acme browser to grab the updated radar.) It's the raw feed, and so is blockier than Wunderground's interpolated/smoothed image, but it still will show you coarse storm features.
Use Wunderground's Stormtrack and Animation options to get a feel for where things are going; try to predict where your specific storm is headed. Pick an intercept/observation point where you think you should be to best view the storm (eg outside the core of the storm, to the SE).
Use the roadmap features of Acme to figure out which roads to take to get to your intercept point safely (eg not through the core) and quickly. Zoom in to view the back roads. Mapper's topo map overlays can give you a sense of the countryside, so you won't plot a course into, say, a valley or other area where your viewing options and escape routes are limited.
For realism, keep track of time and distances you plot so you can allow for realistic driving speeds/times from one location to another. With a large enough screen, you could also use a GPS or other driving-direction software to assist in plotting fastest-time or most-direct routes from location to location. That kind of software will also make your driving time estimates more accurate.
Follow your storm for a while, and see how you do!
More:
http://www.stormtrack.org/library/faq/
http://www.cimms.ou.edu/~doswell/Chasing2.html
http://www.cimms.ou.edu/~stumpf/cethics.html
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