Tag Archive for: flash flooding

Heavy Rains Could Bring Flash and Riverine Flooding This Week

5/17/26 – According to Jeff Lindner, Harris County’s meteorologist, a wet and stormy period mid to late week could bring heavy rainfall, severe thunderstorms, flash flooding, and riverine flooding. The wet and stormy pattern will likely last through the Memorial Day weekend.

Weather Pattern

A slow-moving, upper-level trough will blanket the southwest through much of this week into next weekend while both surface Gulf moisture and high-level Pacific moisture stream into the area.

Additionally, a slow-moving frontal boundary will sag into the area mid to late week. Lindner says, “This is a classic mid to late May stormy pattern for Texas.”

The overall pattern looks stormy as early as late Tuesday. Incoming upper-level disturbances will be hard to time. So, while rain chances will remain high into next weekend, there will be periods of stormy weather followed by breaks.

Complexes of thunderstorms from the west and northwest will move into the area from time to time with the potential for heavy rainfall and severe weather until late week. When the slow-moving/stalled frontal boundary is nearby or overhead, it will help promote more sustained thunderstorm formation and potential cell training.

Rainfall Predictions

Nearly all of the major global weather models show heavy to excessive rainfall potential. However, it will be difficult to predict precisely where storms will train and how long breaks will be between rounds.

These are all details that will be worked out in the next several days as forecast confidence increases.

Expect widespread rainfall amounts of 2-5 inches from Wednesday through Sunday with isolated totals much higher in areas of cell training of slow moving storms. These totals may increase some over the next few days.

Initially, rainfall will soak into the ground. But repeated rounds of rain and training storms could quickly result in higher runoff rates and flash flooding.

Additionally, the large footprint of the forecasted rainfall will yield rises on area rivers systems. And it is possible that some rivers could approach or exceed flood stage by next weekend.

At this time, Pivotal Weather predicts 4.3 inches for  Harris County, 5.1 for Montgomery County, and 6.1 for Walker County. The headwaters for Lake Conroe lie in Walker County and heavy rains there in the past have led to the SJRA opening its flood gates.

For instance, in May 2024, rainfall north of Harris County exceeded 10.0-15.0 inches in many locations. And it exceeded 15.0-20.0 inches on the headwaters of the East Fork and north of Lake Conroe on the West Fork.

Severe Threat

A low daily threat of severe weather (wind and hail) from late Tuesday onward exists. But this threat is conditional on several factors that are hard to determine at this time. Keep your eye on the sky and weather forecasts in coming days. The wet pattern may even linger into next week.

From NWS Storm Prediction Center for 5/19 and 5/20/26.

Posted by Bob Rehak on 5/17/2026

3183 Days since Hurricane Harvey

Flash Flooding Chances Increase for Tuesday, Wednesday

6/16/24 – 8 PM update – As of 8 PM, the National Hurricane Center has increased the chances of tropical formation to 70% from 50% for the disturbance in the Bay of Campeche.

Excessive rainfall and flash flooding chances are increasing for the middle part of the week. Coastal counties could see 8-11 inches in widespread areas with isolated totals topping 12 inches.

According to Harris County Meteorologist Jeff Lindner:

  • The I-10 corridor could experience 5-8 inches (widespread) with isolated totals up to 10 inches
  • North of I-10, people will see 3-5 inches (widespread) with isolated totals up to 8 inches.
  • Much of the rainfall will come over a 36-48 hour period (Tuesday and Wednesday).
National Weather Service gives most of Harris County a 3 out of 4 chance for excessive rainfall.

All of this rain is in association with a tropical disturbance in the Bay of Campeche.

The National Hurricane Center has increased the chances of tropical formation for that red area in the Gulf to 70%.

Whether the storm gets a name or not, it will impact the Houston area in several ways.

Forecasts have been trending upward with rainfall amounts over the last 24 hours. Given the incoming tropical moisture combined with the potential for cell training and high hourly rainfall rates, flash flooding is becoming an increasing concern.

Sustained heavy rains will be possible from Tuesday afternoon into Wednesday over the area.

High hourly rainfall rates will result in rapid onset flash flooding.

Jeff Lindner, Harris County Meteorologist

Uncertainty remains as to where any sustained banding features will form and how far inland the heavy rainfall threat may extend. Stay tuned for changes to the forecast.

Last week, NWS was predicting far less rain from this system.

Significant Rises Likely on Waterways

Significant rises on area creeks, bayous, and rivers will be likely given the rainfall forecast. Where maximum totals occur, overbank flooding will be possible on creeks and bayous. Rivers which are still elevated from the spring rainfall will also likely see additional rises. However, flooding will depend on the position, magnitude, and coverage of the heavier rains and the inland extent.   

Lake Conroe Being Lowered

In preparation, the San Jacinto River Authority continues to lower Lake Conroe. On Sunday morning, it was at 200.82 feet, several inches below its normal level of 201 feet. At 10 AM, SJRA was discharging 660 cubic feet per second.

Lake Houston Discharge Rate Jumps 7X

Downriver, the Coastal Water Authority increased the discharge rate from Lake Houston. The rate jumped from 1386 CFS to 9,905 CFS between 5 AM and 7 AM this morning.

Note steep jump in discharge rate at the far right.

Gusty Winds, Coastal Flooding, Dangerous Seas

As the much-advertised tropical weather event unfolds over the western Gulf of Mexico in the next 24 hours, Lindner anticipates increasing impacts, especially along the Texas Coast.

The plume of tropical moisture will arrive late tonight into Monday. Scattered showers will begin to work toward the coast tonight. Even greater moisture will flow inland Tuesday and Wednesday.

Banding thunderstorms and cell training will create potential for flash flooding. Models have trended upwards in the last 24 hours. The National Weather Service has given all areas south of I-10 a level 3 out of 4 flash flood risk from Tuesday morning to Wednesday morning.

Wind Forecast

According to Lindner, winds will begin to increase on Monday, but really ramp up Tuesday into Wednesday. Coastal areas will likely experience frequent gusts to gale force.

  • Coastal waters: 35-45mph
  • Coastal counties: 25-40mph
  • Inland: 25-30mph

Coastal Flooding Likely Mid-Week During High Tides

Lindner expects building seas and elevated tides to exceed coastal flood thresholds along the upper Texas coast, especially Tuesday and Wednesday. Total water levels are forecasted to reach 4.5-5.5 feet above barnacle level along the Gulf facing beaches late Tuesday into Wednesday and 4.0-5.0 feet in Galveston Bay.

Minor coastal flooding is likely late Tuesday into Wednesday in the usual low lying coastal areas (Bolivar, west end of Galveston Island, Blue Water Highway, Tiki Island, San Leon, Seabrook, Shoreacres).

Water and debris may cover portions of HWY 87 near HWY 124 on Bolivar at high tide. Low lying coastal roads will likely be impacted and covered with sea water at times of high tide.

10-12 Foot Seas

Lindner also warns that extreme dangerous/hazardous marine conditions will develop across all waters Tuesday into Wednesday. Seas will build 5-9 feet on Tuesday offshore and 4-6 feet in bays. Then they will build 10-12 feet on Wednesday offshore and 5-7 feet in bays.

Sustained winds of 30-40mph with frequent gusts of 45mph will be common across our local waters. Expect frequent squalls and periods of heavy rainfall and reduced visibility. Small craft should be secured in port by late Monday and remain in port until conditions improve.  

Posted by Bob Rehak on 6/16/24 based on information from Jeff Lindner, Harris County Meteorologist, and NWS

2483 Days since Hurricane Harvey

More Than 140 Missing After Freak Flash Flood in India

The New York Times, Associated Press, France 24 and IndiaToday have reported a freak flash flood in northern India. It happened near the Himalayas after a portion of a glacier broke away and released pent up water.

The Times said, “Unconfirmed videos on social media showed violent surges of water heading down mountain gorges, washing away bridges and what looked like hydroelectric structures.”

Associated Press reported that the flood killed at least 9 people. They reported 140 missing. “The flood was caused when a portion of Nanda Devi glacier broke off in the Tapovan area of the northern state of Uttarakhand on Sunday morning. A video shared by officials and taken from the side of steep hillside shows a wall of water surging into one of the dams and breaking it into pieces with little resistance before continuing to roar downstream,” said the AP story.

To see a video shared on YouTube by France 24, a French public broadcast service, click here or on the image below.

France 24 video shared on YouTube.

A longer video on IndiaToday shows roiling water splashing hundreds of feet up on canyon walls.

Rescue teams from India and Tibet have rushed to the scene. Towns and villages downstream are being evacuated.

While we don’t have any glaciers in Texas, we do experience flash flooding. This dramatizes how flooding anywhere can change lives in an instant.

To learn more about different types of flooding, view this presentation by the National Weather Service.

Posted by Bob Rehak on 2/7/2020

1258 Days after Hurricane Harvey

Heavy Rainfall, Strong Thunderstorms Likely Friday, Saturday

A series of strong storm systems will converge over south Texas late this week bringing heavy rainfall. Moisture will rapidly increase Thursday afternoon and evening.

Black Friday Looking Like Bleak Friday

“We may even see development of showers over the coastal waters Thursday afternoon that begins to spread inland Thursday evening,” says Jeff Lindner, Harris County’s meteorologist. “Expect showers and thunderstorms to increase and expand in coverage and intensity early Friday. A warm front may begin to slow or even stall over southeast Texas from Friday afternoon into early Saturday. That will allow prolonged heavy rainfall due to cell training.”

Moisture profiles for the Friday afternoon into Saturday point toward heavy rainfall.

“Ingredients are in play for prolonged heavy rainfall, cell training, and possible flash flooding.”

Jeff Lindner, Harris County Meteorologist

Then a cold front will approach the region at some point Saturday into early Sunday helping to focus additional rainfall. The upper level trough will slowly move eastward late Saturday into Sunday leading to decreasing rain chances and cold conditions. 

Up to 5-6 inches Rainfall Possible with Hail Threat

A few of the storms on Friday and Saturday could be strong with the main threat being small hail.

Rainfall amounts over the next 5 days (mainly Friday and Saturday) will likely average 1-3 inches over the region with isolated totals of 5-6 inches possible.

Grounds are dry, so much of this rainfall will likely be beneficial. It will help mitigate increasing drought and fire-weather concerns.

Jeff Lindner

Marginal Risk of Flash Flooding

“However,” says Lindner, “should any sort of heavy rainfall axis develop and anchor over any specific location for a period of time…flash flooding could develop. The main concern would be street flooding with the heavier rainfall rates, but rises on area creeks and bayous will be possible in heavy rainfall materializes in the more urban areas.”

Five day rainfall forecast shows 3-4 inches in the Houston Area.
NOAA gives Houston a marginal chance of flash flooding this weekend.

Posted by Bob Rehak on 11/25/2020

1184 Days since Hurricane Harvey

Tornado Watch for All Southeast Texas Until 3 P.M.

Tornado Watch Extended Until 10PM

As of 3PM on 4/19/2020 the tornado watch was extended until 10PM: A tornado watch is in effect for all of SE Texas. Thunderstorms have begun to develop over SE TX, especially along and near I-10. Air mass is becoming increasingly unstable. The approach of an upper level system from the west and a Pacific cool front along with veering wind profiles will support the formation of scattered to numerous showers and thunderstorms.

Radar Updated at 3:20

Hazards

Storms may become severe with the following hazards:

  • Isolated tornados (mainly N of I-10)
  • Large hail (a few hail report could exceed 2.5 inches in diameter)
  • Damaging winds (60mph or greater)

While the tornado watch includes the entire area, the greatest threat will be generally along and N of US 59 to the west of Houston and then along and N of I-10 east of Houston.

For Your Protection

  • Move to an interior room on the lowest floor of a building.
  • Prepare immediately for large hail and deadly cloud to ground lightning.
  • Seek shelter inside a well-built structure.
  • Stay away from windows.

Continuous cloud to ground lightning is occurring with this storm. Move indoors immediately. Lightning is one of nature’s leading killers. Remember, if you can hear thunder, you are close enough to be struck by lightning.

Torrential rainfall is occurring with this storm, and may lead to flash flooding.

Do not drive your vehicle through flooded roadways.

Posted by Bob Rehak on 4/19/2020 at 9:30am and updated with new radar at 3pm.

964 Days since Hurricane Harvey