A Flood Watch covers 15-16 Brazos Valley counties including Milam, Robertson, Leon, Lee, Burleson, Brazos, Madison, Trinity, Washington, Grimes, Walker, Austin, Waller, Montgomery, and San Jacinto, plus parts of Central, South Texas, and Hill Country.
Geographic Coverage
The Flood Watch encompasses the majority of the Brazos Valley, covering 15 to 16 counties: Milam, Robertson, Leon, Lee, Burleson, Brazos, Madison, Trinity, Washington, Grimes, Walker, Austin, Waller, Montgomery, and San Jacinto. The watch area also extends into parts of Central Texas, South Texas, and the Hill Country.
Timeline and Duration
The Flood Watch becomes effective Thursday evening at 9 PM and remains in effect through Saturday at 4 AM. The National Weather Service notes the potential for the watch area to be extended in both geographic area and duration, with monitoring continuing through Friday evening and adjustments made as needed.
Expected Rainfall and Impacts
Around 2 to 4 inches of rainfall is expected across the watch area, with isolated higher totals possible. Flooding may occur in urban areas and regions with poor drainage. Heavier rainfall could trigger flooding of creeks, streams, and rivers. In some portions within the watch area, there is a potential for life-threatening flooding.
What a Flood Watch Means
A Flood Watch indicates that conditions may develop that lead to flooding, which can be a very dangerous situation. Areas outlined in the watch should remain alert to possible flooding. Residents are advised to turn around and not drive through flooded areas. 
Answer