Are you referring to the ground-based radar images vs. the satellite cloud map being shown in Seasonality?

If so, the reason these do not always match up is because of the time difference between each of the images being generated.  The satellite cloud map that Seasonality shows is an IR cloud image stitched together from multiple satellites around the globe.  This image is generated every 3 hours.  On the other hand, the radar images are updated every 10 minutes.  You could theoretically have a gap of 2 hours and 50 minutes between the satellite image and the radar image, so the position of the precipitation area might not match the cloud area by several miles.  This effect is more dramatic when a storm is developing in an area with a fast (50+ knots) low level jetstream.  With a 3 hour time discrepancy, you could have a storm move 150-200 miles during that time period.