Flood Threats Increasing with Rainfall Predictions
5/20/2026 – According to Jeff Lindner, Harris County’s meteorologist, heavy rainfall will continue this week. “Additional rainfall through the weekend will average 3-5 inches with isolated higher totals…much of this may end up falling on Saturday and Sunday,” he said. “That’s on top of 1-3 inches that fell overnight. “Concern remains high for short-term rainfall rates of 2-4 inches per hour that can lead to rapid-onset flash flooding.” As a result…
“Flash flood and river flood threats will be increasing with time.”
Jeff Lindner
National Weather Service expects total rainfall accumulations to reach 6-8 inches in the next week.
For more details, see below.
Active Weather Pattern Will Continue into Weekend
Earlier forecasts suggested a total of 3-5 inches in coming days. But that has increased. Most of Harris County received 2-3 inches in the last 24 hours alone. See below.
Additional rounds of thunderstorms are likely, according to Lindner.
Latest rounds of storms moved off the coast this morning. Expect a mostly uneventful day with respect to any additional storms. However, this evening another strong disturbance will come out of west Texas and northern Mexico. It will likely produce another complex of thunderstorms. High resolution models suggest a line of storms will form over that part of Texas and move eastward tonight into Thursday morning.
Some models predict the complex of storms will hold together into southeast Texas early Thursday. But other suggest they will weaken before reaching here.
Generally, this activity looks progressive. It will likely bring another 1-2 inches of rainfall. Once it moves through, another break will be possible for much of Thursday. But that will depend on the morning complex of storms pushing through the region and stabilizing the air mass. If not, thunderstorms could develop with heating on Thursday. The NWS Weather Prediction Center shows a level 2 out of 4 risk for excessive rainfall and flash flood threat for Thursday for the entire region.
Additional showers and thunderstorms will be possible on Friday. But confidence in the forecast is low beyond 36 hours. So monitor forecasts late Thursday into Friday morning for approaching disturbances.
Heavy Rainfall Threat Increasing For Weekend
Models indicate more concentrated thunderstorms and heavy rainfall may occur this weekend as a trough over the southwest shift slowly towards west Texas. It is unclear exactly how things will play out into the weekend, but it generally looks wet and the heavy rainfall threat will remain. Colorado State University predicts a heavy rainfall threat for both Saturday and Sunday.
Additional rainfall through the weekend will average 3-5 inches with isolated higher totals. Much of this may end up falling on Saturday and Sunday. Concern remains for high short term rainfall rates of 2-4 inches per hour that can lead to rapid onset flash flooding.
We will need to watch the entire period for any stalling storms or cell training that could quickly result in flash flooding.
Runoff/Flooding
With all the rounds of rainfall, grounds will saturate thoroughly. Run-off will increase into the weekend. A lot of water is going to fall over the next 5-7 days across the region. How quickly that happens will ultimately determine the threat for flooding of creeks, bayous, and rivers.
“Rivers and creeks will rise with rounds of storms and may not be able to recede much before the next round – especially this weekend,” says Lindner. The end result: a slow steady rise in water levels.
Additionally, heavy rainfall will also cause more rapid rises on the more urban creeks and bayous. While these channels can effectively move large amounts of run-off in a short period of time, they can become overwhelmed with intense short-term rainfall rates.
Closely monitor all watersheds into the weekend for rises and any more defined flooding concerns. A good source for that in real-time is the Harris County Flood Warning System. Just remember to click on the Inundation button in the left column. You can also sign up for alerts.
Severe Weather Threat Low
Overall, the severe weather threat is low, but not zero. Overnight storms produced wind gusts of 45-55mph (56mph near Surfside Beach) and these complexes of storms tend to produce gusty winds along their leading edge. The severe threat is likely secondary to the increasing flood threat but will need to be monitored.
Lake Lowering
The Coastal Water Authority started lowering Lake Houston yesterday morning to create more storage for floodwater in the lake and reduce flood threats. As of 11:30 today, the lake was down from its normal level by almost a foot.
The SJRA dashboard shows they are not releasing any water from Lake Conroe but that lake is already down about a half foot. Normal is 201 feet.
Keep your eye on the sky and your ear to the weather radio. And with hurricane season officially starting in 11 days, now may be a good time to check the batteries in all your emergency equipment.
Posted by Bob Rehak at 1PM on Wed., May 20, 2026
3186 Days since Hurricane Harvey
