HOUSTON — Another round of heavy rain is closing out the weekend in Texas, and forecasters say today, Sunday, November 15, brings the greatest concern: increased moisture and heavier rainfall rates have raised the flash flood threat across portions of coastal Texas to Level 2 out of 4, according to FOX Weather, in a report published at 6:52 a.m. EST on Sunday.
Source: FOX Weather
The Weather Prediction Center has placed areas near and south of Interstate 10 under a Slight Risk (Level 2 of 4) for excessive rainfall, indicating an increased potential for flash flooding, while a Marginal Risk (Level 1 of 4) covers much of the surrounding region. The heaviest rain is expected to focus across Southeast Texas, including the Houston area and Corpus Christi, which have already endured a wet weekend.
Source: TheWeather.com (Meteored), citing NWS Houston
How the storm is moving in
A disturbance tied to the storms battering the Pacific Coast is moving east, crossing the Southwest and helping develop an area of low pressure that draws moisture into Texas. A separate description of the same system says the disturbance moving out of the Four Corners region helped trigger low pressure near the Texas-Oklahoma Panhandles, and as it tracks southeastward it will draw warm, humid air into parts of Southeast Texas, creating conditions favourable for thunderstorms.
Source: FOX Weather
Timing matters for Houston drivers. Showers are possible throughout the day, with periods of heavier rain developing near the coast, particularly around Matagorda Bay, on Sunday morning. The line of storms tied to the approaching cold front is expected to move into the Brazos Valley during the mid- to late-morning hours, reach the Houston metro area from late morning into early afternoon, and move offshore by late afternoon. Some storms could repeatedly move over the same locations, increasing the risk of localized flooding.
Source: TheWeather.com (Meteored), citing NWS Houston
The ground is already wet before today's heaviest rain arrives. Rain began on Saturday across portions of Central and North Texas, making for a soggy start to the weekend in Dallas, and some areas within the threat zone have received up to 4 inches of rain over the past week. Heavy rainfall has also soaked parts of South Texas, with some areas picking up 2 to 4 inches over the past 24 to 36 hours.
Source: FOX Weather
Severe weather on top of the rain
Flooding is not the only hazard. The Storm Prediction Center has placed areas generally south of a College Station–Conroe–Liberty line under a Marginal Risk (Level 1 of 5) for severe weather on Sunday. Damaging wind gusts and hail are the primary threats, although an isolated tornado cannot be ruled out. Areas generally west of Interstate 45 and south of Interstate 10 are expected to sit in the warm sector of the cold front, and that sector could extend farther north into Harris County — a distinction forecasters say will determine which areas see the strongest storms.
Source: TheWeather.com (Meteored), citing the Storm Prediction Center
Never drive through flooded roads or around barricades — most flood deaths happen in vehicles. Houston-area residents can watch near-real-time rainfall totals and water levels in local creeks, bayous and drainage channels on the Harris County Flood Control District's Flood Warning System, and should follow watches and warnings from the National Weather Service Houston/Galveston office as conditions develop.
Why street flooding is the main worry
The National Weather Service Houston/Galveston office, in its outlook for Sunday, forecast widespread showers and thunderstorms with locally heavy rainfall, gusty winds and a possibility of isolated severe storms. While that earlier outlook did not anticipate widespread flooding, forecasters have been monitoring the potential for minor street flooding and rapidly accumulating water in low-lying areas and neighbourhoods with poor drainage — and the risk level near the coast has since been raised to Level 2 of 4. Forecasters also stress that a risk outlook is not the same as a flood warning: any watches or warnings issued as conditions develop will carry the specific, immediate hazards.
Source: National Weather Service Houston/Galveston, via My Neighborhood News
For the large Punjabi community in the Houston area and for Punjabi truckers running the Interstate 10 and Interstate 45 freight corridors, the practical risk today is water on the road rather than a single dramatic river flood: repeated downpours over the same neighbourhoods can put low-lying streets, underpasses and low-water crossings under water quickly, and FOX Weather notes that flash flooding is a particular concern in urban areas and communities already soaked by recent storms. Some forecast models keep the highest totals offshore, but the FOX Forecast Center said enough heavy rain could still reach land to create flooding problems.
Source: FOX Weather
What happens next
The cold front is expected to move offshore Sunday evening, but cooler air, lingering moisture and extensive cloud cover will keep conditions unsettled into Monday, with scattered light showers gradually tapering off from north to south. Gusty northeasterly winds will develop behind the front, and Wind Advisories are scheduled for coastal areas, with conditions along the barrier islands expected to become windy enough to warrant an advisory on Sunday. Monday could be the coolest day Houston has experienced since mid-March, with high temperatures expected to remain mostly in the upper 50s. Temperatures then rebound through the middle of next week — into the 60s on Tuesday and the 70s on Wednesday — with drier conditions expected through midweek before rain chances return toward the end of the workweek. The heaviest rainfall should gradually shift offshore as the system advances, and the disturbance is expected to continue toward the Southeast early next week.