Simulation · Scripted scenario — not a real event
Typical storm + high tide (simulation)
What an ordinary heavy-rain day with a high tide looks like, for comparison with the real storms. Not real data.
This replay is a simulation. It shows a common kind of Houston weather day: a band of heavy thunderstorms, the ground already damp, and a normal high tide in Galveston Bay a few hours after the rain. It is on the map so you can compare an ordinary high-water day with the historic storms.
Each gauge location is a real U.S. Geological Survey gauge, but the water levels are scripted. Bayous rise about two to six feet and crest several hours after the heaviest rain, which is typical of how Houston's bayous respond. The bay level follows a normal tide cycle with a small push from onshore wind.
On a day like this, the most common problems are street flooding, water pooling at underpasses, and low spots along bayous. Most homes are not at risk. The danger comes from driving into water you can't see the bottom of. It takes very little moving water to float a car.
High tide mainly matters for places near the bay and the lower ends of channels: Clear Lake, Kemah, Seabrook, Dickinson Bayou, and the lower Buffalo and Sims bayous near the Ship Channel. There, a high tide slows how fast rainwater drains out. For most of Houston, how fast the rain falls matters far more than the tide or the phase of the moon.
For real conditions on any given day, check the Harris County Flood Warning System and NWS Houston/Galveston.