Drawing frontal systems using a station model diagram map can be a difficult task to learn. This animation allows students to draw warm front, cold fronts, and occluded fronts on a map containing live data. Students must also look at the zones of high and low pressure and determine the best placement for the frontal system. There is a button to also check your answers. Be patient in loading the applet because it can be slow, but it is worth the wait.
While not one specific visualization, this link takes you to hundreds of animated sequences on current data. Users looking for recent satellite imagery and storms will find a wealth of information available by year or storm type.
Comparing the density and temperature of two air masses when a warm and cold front approaches in important. While I like this animation, it is a part of Teachersdomain.org. I love the site, but some users may be turned off by the need to create a registration. I personally have no problem with it if I get high quality materials, but others may not appreciate it.