The above radar image was taken just a moment ago, and shows an isolated thunderstorm near Waco. This storm developed along a dryline to the West (yellow dashed line) and moved Eastward.
Additional isolated thunderstorm development is possible along and ahead of the dryline, to the West of the I-35 corridor, during the next 3 hours. Any activity that developes would move Eastward at about 25 mph, and could affect the I-35 corridor later this evening.
There is probably only about a 30% chance of a thunderstorm developing and affecting any one given location, however if that storm does develop there is a near 100% chance that it would become severe. As a result, a Tornado Watch is in effect for much of the I-35 corridor in Central Texas, until 10pm CDT: